TW201519695A - Light source driving circuit, color temperature controller and method for controlling color temperature of light source - Google Patents

Abstract

The present disclosure describes a light source driving circuit, a color temperature controller and a method for controlling color temperature of a light source. The light source driving circuit is configured to drive the light source having an adjustable color temperature. The light source driving circuit includes a power converter coupled between a power source and the light source, and a color temperature controller coupled to the power converter. The power converter is configured to receive power from the power source and produce the adjusted power to the light source. The color temperature controller is configured to receive a switch monitor signal indicating the operation of a power switch coupled between the power source and the power converter, and adjust the color temperature of the light source based on the switch monitor signal. The present disclosure can adjust the color temperature of the light source by operating the power switch, therefore, extra apparatus for controlling, such as a specially designed switch with adjusting buttons, can be avoided and the cost can be reduced.

Description

Light source driving circuit, color temperature controller and method for controlling color temperature of light source

The invention relates to the field of light sources, in particular to a light source driving circuit, a color temperature controller and a method for controlling the color temperature of the light source.

In recent years, new light sources such as light-emitting diodes (LEDs) have made advances in materials and manufacturing. LEDs are characterized by high efficiency, long life and bright colors, which can be applied to the fields of automobiles, computers, communications, military and daily necessities. For example, LED lights can replace traditional incandescent lamps as illumination sources.

FIG. 1 is a schematic diagram of a conventional LED driving circuit 100. The LED drive circuit 100 utilizes the LED chain 106 as a light source. LED chain 106 includes a plurality of LEDs in series. The power converter 102 is operative to convert the DC input voltage Vin to a desired DC output voltage Vout for powering the LED chain 106. The switch 104 connected to the LED drive circuit 100 can connect or disconnect the LED chain 106 with the input voltage Vin to turn the LED lamp on or off. Power converter 102 receives the feedback signal from current sense resistor Rsen and regulates output voltage Vout to cause LED chain 106 to produce the desired brightness. One of the disadvantages of this conventional solution is that the desired brightness is preset, and the user cannot adjust the brightness during use.

FIG. 2 shows a schematic diagram of another conventional LED drive circuit 200. electric power Converter 102 is operative to convert DC input voltage Vin to a desired DC output voltage Vout for powering LED chain 106. The switch 104 connected to the LED drive circuit 100 can connect or disconnect the LED chain 106 with the input voltage Vin to turn the LED lamp on or off. LED chain 106 is coupled to linear current regulator 208. The operational amplifier 210 in the linear current regulator 208 compares the reference signal REF with the current monitoring signal from the current detecting resistor Rsen and generates a control signal to linearly adjust the resistance of the transistor Q1 to flow through the LED chain 106. The current can be adjusted accordingly. Applying this conventional scheme, in order to control the light output of the LED chain 106, the user needs to adjust the reference signal REF by using a special component such as a specially designed switch with an adjustment button or a switch capable of receiving a remote control signal.

The technical problem to be solved by the present invention is to provide a light source driving circuit, a color temperature controller and a method for controlling the color temperature of the light source, which can realize the adjustment of the color temperature of the light source in a simple and convenient manner.

The present invention provides a light source driving circuit for driving a light source having a color temperature, the light source driving circuit comprising: a power converter coupled between a power source and the light source, receiving from the power source An electrical energy and providing an adjusted electrical energy to the light source; and a color temperature controller coupled to the power converter to receive a switch indicating an operation of coupling a power switch between the power source and the power converter The signal is monitored and a color temperature of the light source is adjusted based on the switch monitoring signal.

The invention further provides a color temperature controller, the color temperature controller comprising: a driving unit, receiving a current monitoring signal indicating a current value flowing through a light source, and according to The current monitoring signal generates a driving signal to control a power converter to provide an adjusted power to the light source; and a control unit coupled to the driving unit to receive a switch monitoring signal indicating an operation of a power switch, and based on The switch monitoring signal adjusts a color temperature of the light source, wherein the power switch is coupled between the power source and the power converter.

The invention also provides a method for controlling the color temperature of a light source, the method comprising: receiving a power from a power source and providing a regulated power to a light source by a power converter; the receiving indication is coupled to the power source and the power converter a switch monitoring signal for an operation of a power switch; and adjusting a color temperature of the light source based on the switch monitoring signal.

Compared with the prior art, the light source driving circuit, the color temperature controller and the method for controlling the color temperature of the light source of the present invention can realize the adjustment of the color temperature of the light source by operating the power switch without using an additional dedicated component. Simple and convenient, and cost savings.

100‧‧‧LED drive circuit

102‧‧‧Power Converter

104‧‧‧ switch

106‧‧‧LED chain

200‧‧‧LED drive circuit

208‧‧‧Linear current regulator

210‧‧‧Operational Amplifier

300‧‧‧Light source drive circuit

304‧‧‧Power switch

306‧‧•AC/DC converter

308‧‧‧ dimming controller

310‧‧‧Power Converter

312‧‧‧LED chain

314‧‧‧ Current monitor

400‧‧‧Light source drive circuit

502‧‧‧ dimmer

504‧‧‧ pulse signal generator

506‧‧‧Trigger monitoring unit

508‧‧‧Starting and low voltage locking circuit

510‧‧‧Operational Amplifier

512‧‧‧Metal Oxide Semiconductor Field Effect Transistor

514‧‧‧Metal Oxide Semiconductor Field Effect Transistor

515‧‧‧Metal Oxide Semiconductor Field Effect Transistor

516‧‧‧ comparator

518‧‧‧ comparator

520‧‧‧SR trigger

522‧‧‧SR trigger

524‧‧‧ and gate

526‧‧‧ counter

528‧‧‧Digital-to-Analog Converter

530‧‧‧ Pulse width modulation signal generator

532‧‧‧current source

534‧‧‧ comparator

536‧‧‧ pulse signal

538‧‧‧Control signal

540‧‧‧ switch

541‧‧‧ switch

542‧‧‧Switch

602‧‧‧ Current

1000‧‧‧Light source drive circuit

1008‧‧‧ dimming controller

1102‧‧‧Dimmer

1104‧‧‧clock generator

1106‧‧‧Trigger monitoring unit

1126‧‧‧ counter

1400‧‧‧Light source drive circuit

1408‧‧‧ dimming controller

1450‧‧‧Switch monitoring signal

1452‧‧‧Switch control signal

1454‧‧‧Induction signal

1480‧‧‧ components

1502‧‧‧Dimmer

1504‧‧‧ counter

1506‧‧‧Reference signal generator

1508‧‧‧PWM generator

1510‧‧‧Enable signal

1900‧‧‧Light source drive circuit

1908‧‧‧ dimming controller

1952‧‧‧ pulse signal

1954‧‧‧Control signal

2002‧‧‧Dimmer

2004‧‧‧Mode Selection Module

2006‧‧‧current source

2008‧‧‧Switch

2010‧‧‧ drive

2300‧‧‧Light source drive circuit

2302‧‧‧DC/DC Converter

2304‧‧‧Transformers

2305‧‧‧ primary winding

2306‧‧‧Color temperature controller

2307‧‧‧secondary winding

2308‧‧‧First LED chain

2309‧‧‧Auxiliary winding

2310‧‧‧Second LED chain

2312‧‧‧First control switch

2314‧‧‧Second control switch

2316‧‧‧ Current monitor

2325‧‧‧ magnetic core

2410‧‧‧ drive

2411‧‧‧Error amplifier

2413‧‧‧Sawtooth signal generator

2415‧‧‧ comparator

2417‧‧‧ Pulse width modulation signal generator

2420‧‧‧Control unit

2421‧‧‧Timer

2423‧‧‧First D-type flip-flop

2425‧‧‧Second D-type flip-flop

2427‧‧‧First Gate

2429‧‧‧Second Gate

2431‧‧‧Decision unit

2433‧‧‧Inverter

Figure 1 is a circuit diagram of a conventional LED driving circuit.

Figure 2 is a circuit diagram of another conventional LED drive circuit.

Fig. 3 is a schematic view of a light source driving circuit according to an embodiment of the present invention.

Fig. 4 is a circuit diagram of a light source driving circuit according to an embodiment of the present invention.

Figure 5 is a schematic view showing the structure of the dimming controller of Figure 4.

Figure 6 is a schematic diagram of signal waveforms in analog dimming mode.

Figure 7 is a schematic diagram of signal waveforms in pulse dimming mode.

Figure 8 is a diagram showing the operation mode of a light source driving circuit according to an embodiment of the present invention.

It is intended that the light source driving circuit includes the dimming controller shown in FIG.

Figure 9 is a flow chart of a method of power control of a light source in accordance with an embodiment of the present invention.

Fig. 10 is a circuit diagram of a light source driving circuit according to an embodiment of the present invention.

Figure 11 is a schematic view showing the structure of the dimming controller of Figure 10.

Figure 12 is a schematic diagram showing the operation of a light source driving circuit according to an embodiment of the present invention, the light source driving circuit including the dimming controller shown in Figure 11.

Figure 13 is a flow chart of a method of power control of a light source in accordance with an embodiment of the present invention.

Fig. 14A is a circuit diagram of a light source driving circuit according to an embodiment of the present invention.

Figure 14B is a schematic diagram of one embodiment of the power switch of Figure 14A.

Fig. 15 is a view showing the configuration of the dimming controller of Fig. 14A according to an embodiment of the present invention.

Figure 16 is a signal diagram of a light source driving circuit including the dimming controller of Figure 15 in accordance with an embodiment of the present invention.

Figure 17 is another signal diagram of a light source driving circuit including the dimming controller of Figure 15 in accordance with an embodiment of the present invention.

Figure 18 is a flow diagram of a method of controlling dimming of an LED light source in accordance with an embodiment of the present invention.

Fig. 19 is a circuit diagram of a light source driving circuit according to an embodiment of the present invention.

Figure 20 is a diagram of the dimming controller of Figure 19 in accordance with an embodiment of the present invention. Schematic.

Figure 21 is a signal diagram of a light source driving circuit including the dimming controller of Figure 19, in accordance with an embodiment of the present invention.

Figure 22 is a flow chart of a method of controlling dimming of an LED light source in accordance with an embodiment of the present invention.

Fig. 23A is a schematic diagram of a light source driving circuit according to an embodiment of the present invention.

Fig. 23B is a circuit diagram of a light source driving circuit according to an embodiment of the present invention.

Figure 24 is a schematic view showing the structure of the color temperature controller in Figure 23B.

Fig. 25 is a signal waveform diagram of a light source driving circuit including the color temperature controller shown in Fig. 24 according to an embodiment of the present invention.

Figure 26 is a signal waveform diagram of a light source driving circuit including the color temperature controller shown in Figure 24 according to another embodiment of the present invention.

Figure 27 is a flow chart showing a method of controlling the color temperature of a light source according to an embodiment of the present invention.

A detailed description of the embodiments of the present invention will be given below. Although the invention has been illustrated and described with respect to the embodiments, it should be noted that the invention is not limited to the embodiments. Rather, the invention is to cover all modifications, alternatives and equivalents of the scope of the invention as defined by the appended claims. In the following detailed description of the invention, reference to the claims However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. In other examples, the well-known schemes, procedures, components, and circuits are not detailed. Description is provided to highlight the gist of the present invention.

3 is a schematic diagram of a light source driving circuit 300 in accordance with one embodiment of the present invention. In one embodiment, power switch 304 is coupled between power source Vin and light source drive circuit 300 for selectively connecting light source drive circuit 300 to power source Vin. The light source driving circuit 300 includes an AC/DC converter 306 for converting an AC input voltage Vin from a power source into a DC output voltage Vout, and an electric power connected to the AC/DC converter 306 for supplying the adjusted energy to the LED chain 312. The converter 310 is connected to the power converter 310 for receiving a switch monitoring signal indicating the action of the power switch 304 and controlling the dimming controller 308 output by the power converter 310 according to the switch monitoring signal, and for monitoring the flow through the LED chain 312. The current monitor 314 of the current. In one embodiment, the power switch 304 is a power switch placed on the wall.

In operation, the AC/DC converter 306 converts the input AC voltage Vin into a DC output voltage Vout. Power converter 310 receives DC voltage Vout and provides an adjusted voltage to LED chain 312. Current monitor 314 generates a current monitoring signal that indicates the magnitude of the current flowing through LED chain 312. The dimming controller 308 monitors the action of the power switch 304, receives a current monitoring signal from the current monitor 314, and controls the power converter 310 to regulate the power of the LED chain 312 in accordance with the action of the power switch 304. In one embodiment, dimming controller 308 operates in analog dimming mode to adjust the power of LED chain 312 by adjusting a reference signal that determines the peak value of the LED current. In another embodiment, the dimming controller 308 operates in a burst dimming mode to adjust the power of the LED chain 312 by adjusting the duty cycle of a pulse width modulated signal (PWM signal). By adjusting the electrical energy of the LED chain 312, the brightness of the LED chain 312 can be adjusted accordingly.

4 shows the power of the light source driving circuit 400 according to an embodiment of the present invention. Road map. Figure 4 will be described in conjunction with Figure 3. The same components in FIG. 4 as those in FIG. 3 have similar functions, and will not be repeatedly described herein for the sake of brevity.

Light source drive circuit 400 includes a power converter 310 coupled between the power source and LED chain 312 for receiving power from the power source and providing regulated power to LED chain 312. In the embodiment of FIG. 4, power converter 310 is a buck converter that includes inductor L1, diode D4, and control switch Q16. In the embodiment of FIG. 4, control switch Q16 is external to dimming controller 308. In other embodiments, the control switch Q16 can also be integrated into the interior of the dimming controller 308.

The dimming controller 308 receives the switch monitoring signal and controls the switch Q16 in series with the LED chain 312 according to the switch monitoring signal to adjust the adjusted output of the power converter 310 (including the inductor L1, the diode D4 and the control switch Q16). Electrical energy. The switch monitor signal indicates the action of a power switch, such as a power switch 304 connected between the power source and the light source drive circuit. The light source driving circuit 400 further includes an AC/DC converter 306 for converting the AC input voltage Vin into a DC output voltage Vout. Light source drive circuit 400 also includes a current monitor 314 for monitoring current flow through LED chain 312. In the embodiment shown in FIG. 4, the AC/DC converter 306 is a bridge rectifier including a diode D1, a diode D2, a diode D7, a diode D8, a diode D10, and a capacitor C9. The current monitor 314 includes a current detecting resistor R5.

In one embodiment, the 埠 of the dimming controller 308 includes: HV_GATE, SEL, CLK, RT, VDD, CTRL, MON, and GND.埠HV_GATE is connected to the switch Q27 through a resistor R15 for controlling the conduction state (such as the on/off state) of the switch Q27 connected to the LED chain 312. Capacitor C11 is connected between 埠HV_GATE and ground for adjusting the gate voltage of switch Q27.

In actual use, the user can choose to connect 埠SEL through resistor R4. To the ground, as shown in Figure 4, or by connecting 埠SEL directly to ground, the analog dimming mode or the pulse dimming mode can be selected accordingly.

埠CLK is connected to the AC/DC converter 306 through a resistor R3 while being connected to ground through a resistor R6.埠CLK receives a switch monitoring signal that indicates the action of power switch 304. In one embodiment, the switch monitor signal is generated at a node between resistor R3 and resistor R6. Capacitor C12 is connected in parallel with resistor R6 to filter out unwanted noise.埠RT is coupled to ground through resistor R7 for determining the frequency of the pulse signal generated by dimming controller 308.

埠VDD is connected to switch Q27 through diode D9 for powering dimming controller 308. In one embodiment, an energy storage unit, such as capacitor C10, is coupled between 埠VDD and ground to power dimming controller 308 when power switch 304 is turned off. In another embodiment, the energy storage unit can also be integrated inside the dimming controller 308.埠 GND is connected to ground.

埠 CTRL is connected to switch Q16. Switch Q16 is coupled in series with LED chain 312 and switch Q27 and is coupled to ground via current monitoring resistor R5. The dimming controller 308 controls the conductive state of the switch Q16 by a control signal outputted on the 埠CTRL to adjust the adjusted electrical energy output by the power converter 310.埠MON is coupled to current monitoring resistor R5 for receiving a current monitoring signal indicative of current flowing through LED chain 312. When switch Q27 is turned "on", dimming controller 308 regulates the current flowing through LED chain 312 by controlling switch Q16.

In operation, when the power switch 304 is turned "on", the AC/DC converter 306 converts the input AC voltage Vin into a DC output voltage Vout. A voltage having a preset voltage value on 埠HV_GATE is applied to the switch Q27 through the resistor R15, thereby turning on the switch Q27.

If dimming controller 308 turns on switch Q16, DC voltage Vout will be LED Chain 312 supplies power and charges inductor L1. Current flows through inductor L1, LED chain 312, switch Q27, switch Q16, and resistor R5 to ground. If the dimming controller 308 turns off the switch Q16, current flows through the inductor L1, the LED chain 312, and the diode D4. Inductor L1 is discharged to power LED chain 312. Therefore, the dimming controller 308 can adjust the adjusted electrical energy output by the power converter 310 by controlling the switch Q16.

When the power switch 304 is turned off, the capacitor C10 is discharged to supply power to the dimming controller 308. The voltage across resistor R6 drops to zero, so that dimming controller 308 can monitor a switch monitor signal indicating that power switch 304 is open on 埠CLK. Similarly, when the power switch 304 is turned "on", the voltage across the resistor R6 rises to a predetermined voltage value, so that the dimming controller 308 can monitor a switch monitor signal indicating that the power switch 304 is turned "on" on the 埠CLK. If a disconnect operation is detected, the dimming controller 308 can pull the voltage on 埠HV_GATE to 0 to turn off the switch Q27, causing the LED chain 312 to be powered down after the inductor L1 is completely discharged. After monitoring the disconnect operation of the power switch 304, the dimming controller 308 adjusts a reference signal indicative of the desired brightness of the LED chain 312. When the power switch 304 is turned on next time, the brightness of the LED chain 312 can be adjusted according to the adjusted desired brightness. In other words, the output brightness of the LED chain 312 can be adjusted by the dimming controller 308 according to the opening operation of the power switch 304.

FIG. 5 is a schematic structural view of the dimming controller 308 of FIG. Figure 5 will be described in conjunction with Figure 4. The same components in Fig. 5 as those in Fig. 4 have similar functions, and will not be repeatedly described herein for the sake of brevity.

The dimming controller 308 includes a trigger monitoring unit 506, a dimmer 502, and a pulse signal generator 504. The trigger monitoring unit 506 is connected to ground through the Zener diode ZD1. The trigger monitoring unit 506 receives a switch monitoring signal through the 埠CLK, the switch monitoring signal indicating an external power switch The action of 304. When the action of the external power switch 304 is monitored, the trigger monitoring unit 506 generates a drive signal to drive the counter 526. The trigger monitoring unit 506 also further controls the conduction state of the switch Q27. The dimmer 502 generates a reference signal REF that adjusts the power of the LED chain 312 in an analog to dimming manner. The dimmer 502 can also generate a control signal 538 that adjusts the power of the LED chain 312 by adjusting the duty cycle of the pulse width modulation signal PWM1. The pulse signal generator 504 generates a pulse signal for turning on the switch Q16. The dimming controller 308 also includes a startup and low voltage lock (UVL) circuit 508 coupled to 埠 VDD for selectively activating one or more components within the dimming controller 308 based on different electrical conditions.

In one embodiment, if the voltage on 埠 VDD is higher than the first predetermined voltage, the startup and low voltage lockout circuit 508 will activate all of the components in the dimming controller 308. When the power switch 304 is turned off, if the voltage on 埠 VDD is lower than the second predetermined voltage, the startup and low voltage lockout circuit 508 will turn off the components of the dimming controller 308 other than the trigger monitoring unit 506 and the dimmer 502. Save energy. If the voltage on 埠 VDD is lower than the third predetermined voltage, the startup and low voltage lockout circuit 508 will turn off the trigger monitoring unit 506 and the dimmer 502. In one embodiment, the first preset voltage is higher than the second preset voltage, and the second preset voltage is higher than the third preset voltage. Since the dimming controller 308 can be powered by the capacitor C10 via 埠VDD, the trigger monitoring unit 506 and the dimmer 502 can operate for a period of time even after the power switch 304 is turned off.

In dimming controller 308, 埠SEL is coupled to current source 532. The user can select the dimming mode by configuring 埠SEL, such as connecting 埠SEL directly to ground or connecting 埠SEL to ground through a resistor. In one embodiment, the dimming mode is determined by measuring the voltage on the 埠SEL. If 埠SEL is directly connected to ground, the voltage on 埠SEL is approximately zero. A control circuit (not shown) can turn on the switch 540, turn off the switch 541 and the switch 542, thereby dimming Controller 308 can operate in analog dimming mode and adjust the power of LED chain 312 by adjusting reference signal REF. In one embodiment, if 埠SEL is coupled to ground through resistor R4 (shown in Figure 4) and R4 has a predetermined resistance, then the voltage on 埠SEL is greater than zero. The control circuit opens switch 540, turns on switch 541, and switches 542. Thus, the dimming controller 308 operates in the pulse dimming mode and adjusts the power of the LED chain 312 by adjusting the duty cycle of the pulse width modulation signal PWM1. In other words, by controlling the conduction states of the switch 540, the switch 541, and the switch 542, different dimming modes can be selected. The conduction state of switch 540, switch 541, and switch 542 is determined by the voltage on 埠SEL.

Pulse signal generator 504 is coupled to ground via 埠RT and resistor R7 to generate a pulse signal 536 for turning on switch Q16. The pulse signal generator 504 can have a different structure and is not limited to the structure shown in FIG.

In the pulse signal generator 504, the non-inverting terminal of the operational amplifier 510 receives the preset voltage V1, and thus the inverting terminal voltage of the operational amplifier 510 is also V1. Current IRT flows to ground through 埠RT and resistor R7. The current I1 flowing through the metal oxide semiconductor field effect transistor (MOSFET) 514 and the metal oxide semiconductor field effect transistor 515 has the same magnitude as the current IRT. The metal oxide semiconductor field effect transistor 514 and the metal oxide semiconductor field effect transistor 512 constitute a current mirror, so the current I2 flowing through the metal oxide semiconductor field effect transistor 512 is also the same size as the current IRT. The output of comparator 516 and the output of comparator 518 are coupled to the S input and R input of SR flip flop 520, respectively. The inverting terminal of the comparator 516 receives the preset voltage V2. The non-inverting terminal of the comparator 518 receives the preset voltage V3. In one embodiment, V2 is greater than V3 and V3 is greater than zero. Capacitor C4 is coupled between metal oxide semiconductor field effect transistor 512 and ground, and is coupled at one end to a node between the non-inverting terminal of comparator 516 and the inverting terminal of comparator 518. SR trigger The Q output of 520 is coupled to switch Q15 and also to the S input of SR flip flop 522. Switch Q15 is connected in parallel with capacitor C4. The conduction state of switch Q15 is determined by the Q output of SR flip flop 520.

The initial voltage across capacitor C4 is approximately zero, less than V3. Therefore, the R input of the SR flip-flop 520 receives the digital signal 1 output by the comparator 518. The Q output of SR flip flop 520 is set to digital signal 0, thereby turning off switch Q15. When the switch Q15 is turned off, the capacitor C4 is charged by the current I2, so the voltage across the capacitor C4 rises. When the voltage across C4 is greater than V2, the S input of SR flip flop 520 receives the digital signal 1 output by comparator 516. The Q output of the SR flip-flop 520 is set to a digital signal 1, thereby turning on the switch Q15. When the switch Q15 is turned on, the capacitor C4 is discharged through the switch Q15, so that the voltage across the terminals is lowered. When the voltage across capacitor C4 drops to V3, comparator 518 outputs digital signal 1, and the Q output of SR flip-flop 520 is set to digital signal 0, thereby opening switch Q15. Capacitor C4 is then charged again by the action of current I2. As previously described, pulse signal generator 504 produces a pulse signal 536 at the Q output of SR flip flop 520, which includes a series of pulses. Pulse signal 536 is passed to the S input of SR flip flop 522.

The trigger monitoring unit 506 monitors the action of the power switch 304 via 埠CLK. If the action of the power switch 304 is detected at 埠CLK, the trigger monitoring unit 506 generates a drive signal to drive the counter 526. In one embodiment, when power switch 304 is turned "on", the voltage on 埠CLK rises, which is equal to the voltage across resistor R6, as shown in FIG. When the power switch 304 is turned off, the voltage on 埠CLK drops to zero. Therefore, the switch monitoring signal indicating the action of the power switch 304 can be monitored at 埠CLK. In one embodiment, the trigger monitoring unit 506 generates a drive signal when a disconnect action is detected at 埠CLK.

The trigger monitoring unit 506 also controls the conduction state of the switch Q27 by 埠HV_GATE. When the power switch 304 is turned on, the breakdown voltage across the Zener diode ZD1 passes through the resistor R15. It is applied to the switch Q27, thereby turning on the switch Q27. The trigger monitoring unit 506 can pull down the voltage of 埠HV_GATE to 0 to turn off the switch Q27. In one embodiment, when the disconnection action of the power switch 304 is detected on the 埠CLK, the trigger monitoring unit 506 turns off the switch Q27. When the turn-on action of the power switch 304 is detected on the 埠CLK, the trigger monitoring unit 506 turns on the switch Q27.

In one embodiment, dimmer 502 includes a counter 526 coupled to trigger monitoring unit 506 for counting the action of power switch 304. The dimmer 502 also includes a digital to analog converter 528 coupled to the counter 526 and a pulse width modulated signal generator 530 coupled to the digital to analog converter 528. Counter 526 is driven by a drive signal generated by trigger monitoring unit 506. Specifically, when the power switch 304 is turned off, the trigger monitoring unit 506 detects a falling edge on the 埠CLK, thereby generating a drive signal. The count value of counter 526 is incremented by the drive signal (e.g., incremented by one). The digital to analog converter 528 reads the count value from the counter 526 and generates a dimming signal based on the count value (the dimming signal can be the control signal 538 or the reference signal REF). The dimming signal can be used to adjust the target power value of power converter 310 to adjust the brightness of LED chain 312.

In the pulse dimming mode, switch 540 is open, switch 541 and switch 542 are turned "on". The inverting terminal of comparator 534 receives reference signal REF1. REF1 is a DC signal with a preset voltage value. The voltage of REF1 determines the current peak of LED chain 312, which in turn determines the maximum brightness of LED chain 312. In this pulse dimming mode, the dimming signal is applied to a control signal 538 on the pulse width modulation signal generator 530, which can adjust the duty cycle of the pulse width modulation signal PWM1. By adjusting the duty cycle of PWM1, the brightness of LED chain 312 is equal to or lower than the maximum brightness determined by REF1. For example, if the duty cycle of PWM1 is 100%, then LED chain 312 has maximum brightness. If the duty cycle of PWM1 is less than 100%, the brightness of LED chain 312 is lower than the maximum brightness.

In the analog dimming mode, switch 540 is turned "on" and switch 541 and switch 542 are turned "off". In this analog dimming mode, the dimming signal is the reference signal REF. The reference signal REF is an analog signal with an adjustable voltage. Digital to analog converter 528 adjusts the voltage of REF based on the count value of counter 526. The voltage of REF determines the current peak of LED chain 312, which in turn determines the maximum brightness of LED chain 312. Therefore, by adjusting REF, the brightness of the LED chain 312 can be adjusted accordingly.

In one embodiment, the count value of the counter is increased such that the digital to analog converter 528 lowers the voltage of REF. For example, if the count value is 0, the digital to analog converter 528 adjusts the voltage of REF to V4. If the trigger monitoring unit 506 monitors the turn-off action of the power switch 304 to cause the count value to increase to 1, the digital-to-analog converter 528 adjusts the voltage of REF to V5, and V5 is less than V4. In another embodiment, the count value of the counter is increased such that the digital to analog converter 528 boosts the voltage of REF.

In one embodiment, when the count value of counter 526 reaches a maximum value, the count value is reset to zero. If the counter 526 is a two-digit counter, the count value will increase from 0 to 1, 2, 3, and then return to 0 after the fourth disconnect operation. Accordingly, the brightness of the LED chain 312 is sequentially adjusted from the first stage to the second stage, the third stage, the fourth stage, and then back to the first stage.

The inverting terminal of the comparator 534 can selectively receive the reference signal REF or the reference signal REF1. In analog dimming mode, the inverting terminal of comparator 534 receives reference signal REF through switch 540. In the pulse dimming mode, the inverting terminal of the comparator 534 receives the reference signal REF1 through the switch 541. The non-inverting terminal of comparator 534 is coupled to current monitoring resistor R5 via 埠MON to receive current monitoring signal SEN from current monitoring resistor R5. Current monitoring signal SEN voltage Represents the amount of current flowing through LED chain 312 when switches Q27 and Q16 are open.

The output of comparator 534 is coupled to the R input of SR flip flop 522. The Q output of SR flip flop 522 is coupled to AND gate 524. The pulse width modulation signal PWM1 generated by the pulse width modulation signal generator 530 is applied to the AND gate 524. The gate 524 outputs a control signal, and Q16 is controlled by 埠CTRL.

If the analog dimming mode is selected, switch 540 is turned "on" and switches 541 and 542 are turned "off". Switch Q16 is controlled by SR flip flop 522. When the power switch 304 is turned on, the breakdown voltage across the Zener diode ZD1 causes the switch Q27 to be turned on. Under the action of the pulse signal 536 generated by the pulse signal generator 504, the SR flip-flop 522 produces a digital signal 1 at the Q output, causing the switch Q16 to turn "on". Current flows through inductor L1, LED chain 312, switch Q27, switch Q16, and current monitoring resistor R5 to ground. Since the inductor L1 blocks the jump of the current, the current gradually increases. The voltage across the current monitoring resistor R5 (ie, the voltage of the current monitoring signal SEN) will increase. When the voltage of SEN is greater than the voltage of the reference signal REF, the comparator 534 outputs the digital signal 1 to the R input of the SR flip-flop 522, so that the SR flip-flop 522 outputs the digital signal 0, causing the switch Q16 to open. After switch Q16 is turned off, inductor L1 is discharged to supply power to LED chain 312. The current flowing through the inductor L1, the LED chain 312, and the diode D4 is gradually reduced. When the SR flip-flop 522 receives a pulse at the S input, the switch Q16 is turned "on" and the current of the LED chain 312 flows through the current monitoring resistor R5 to ground. When the voltage of the current monitoring signal SEN is greater than the voltage of the reference signal REF, the switch Q16 is again turned off by the SR flip-flop 522. As described above, the reference signal REF determines the peak value of the current flowing through the LED chain 312, that is, determines the brightness of the LED chain 312. By adjusting REF, the brightness of LED chain 312 is adjusted accordingly.

In the analog dimming mode, if the power switch 304 is turned off, as shown in FIG. 4, the capacitor C10 is discharged to supply power to the dimming controller 308. When the trigger monitoring unit 506 monitors at 埠CLK When the power switch 304 is turned off, the count value of the counter 526 is incremented by one. The opening action of the power switch 304 causes the trigger monitoring unit 506 to open the switch Q27. The change in the count value causes the digital to analog converter 528 to adjust the voltage of the reference signal REF from the first voltage value to the second voltage value. Therefore, when the power switch 304 is turned on again, the brightness of the LED chain 312 is adjusted due to the adjustment of the reference signal REF.

If pulse dimming mode is selected, switch 540 is open and switch 541 and switch 524 are turned "on". The inverting terminal of the comparator 534 receives the reference signal REF1 having a preset voltage value. The switch Q16 is controlled by the SR flip-flop 522 and the pulse width modulation signal PWM1 and the gate 524. The reference signal REF1 determines the peak current of the LED chain 312, which determines the maximum brightness of the LED chain 312. The duty cycle of the pulse width modulation signal PWM1 determines the on/off time of the switch Q16. When the pulse width modulation signal PWM1 is the digital signal 1, the conduction state of the switch Q16 is determined by the output of the Q output terminal of the SR flip-flop 522. When the pulse width modulation signal PWM1 is a digital signal 0, the switch Q16 is turned off. By adjusting the duty cycle of the pulse width modulation signal PWM1, the power of the LED chain 312 can be adjusted accordingly. Therefore, the reference signal REF1 and the pulse width modulation signal PWM1 together determine the brightness of the LED chain 312.

In the pulse dimming mode, when the power switch 304 is turned off, the turn-off operation is monitored by the trigger monitoring unit 506 at 埠CLK. The trigger monitoring unit 506 turns off Q27 and generates a drive signal. Under the action of the drive signal, the count value of the counter 526 is increased, for example by one. The digital to analog converter 528 generates a control signal 538 such that the duty cycle of the pulse width modulation signal PWM1 changes from the first stage to the second stage. Therefore, when the power switch 304 is turned "on" again, the brightness of the LED chain 312 will be adjusted with the target brightness value as a target. The target luminance value is determined by the reference signal REF1 and the pulse width modulation signal PWM1.

Figure 6 shows a schematic diagram of the signal waveform in the analog dimming mode. Which includes the flow The current 602 through the LED chain 312, the pulse signal 536, the output V522 of the SR flip-flop 522, and the output V524 of the gate 524, and the on/off state of the switch Q16. Figure 6 will be described in conjunction with Figures 4 and 5.

Pulse signal generator 504 generates pulse signal 536. Under the action of each pulse of pulse signal 536, SR flip-flop 522 produces a digital signal 1 at the Q output. The generation of the digital signal 1 by the SR flip-flop 522 at the Q output causes the switch Q16 to turn "on". When switch Q16 is turned on, inductor L1 is charged and current 602 is increased. When the current 602 reaches the peak Imax, that is, the voltage of the current monitoring signal SEN is equal to the voltage of the reference signal REF, the comparator 534 outputs the digital signal 1 to the R input of the SR flip-flop 522 such that the SR flip-flop 522 is at the Q output. The digital signal 0 is output. Outputting the digital signal 0 at the Q output of the SR flip-flop 522 causes the switch Q16 to open, while the discharge of the inductor L1 supplies power to the LED chain 312 and the current 602 decreases. In the analog dimming mode, by adjusting the reference signal REF, the average current value flowing through the LED chain 312 is adjusted accordingly, so that the brightness of the LED chain 312 is also adjusted.

Figure 7 shows a schematic diagram of the signal waveform in pulse dimming mode. These include current 602 flowing through LED chain 312, pulse signal 536, output V522 of SR flip flop 522, and output V524 of gate 524, on/off state of switch Q16, and pulse width modulation signal PWM1. Figure 7 will be described in conjunction with Figures 4 and 5.

When PWM1 is a digital signal 1, the relationship between the current 602 flowing through the LED chain 312, the on/off states of the pulse signals 536, V522, V524 and the switch Q16 is similar to that of FIG. When PWM1 is a digital signal 0, the output of AND gate 524 becomes digital signal 0. Thereby the switch Q16 is turned off and the current 602 is decreased. If PWM1 maintains the state of digital signal 0 long enough, current 602 will decrease to zero. In the pulse dimming mode, by adjusting the duty cycle of PWM1, the average current value flowing through the LED chain 312 is adjusted accordingly, so that the brightness of the LED chain 312 is also adjusted.

FIG. 8 is a schematic diagram showing the operation of a light source driving circuit according to an embodiment of the present invention. Figure 8 will be described in conjunction with Figure 5.

In the embodiment shown in FIG. 8, whenever the trigger monitoring unit 506 detects the opening action of the power switch 304, the counter 526 count value is incremented by one. Counter 526 is a two-digit counter with a maximum count of three.

In analog dimming mode, digital to analog converter 528 reads the count value from counter 526. The increase in the count value causes the digital to analog converter 528 to turn down the voltage of the reference signal REF. The voltage of the reference signal REF determines the peak value Imax of the current of the LED chain 312, that is, the average value of the current of the LED chain 312. In the pulse dimming mode, digital to analog converter 528 reads the count value from counter 526. The increase in the count value causes the digital to analog converter 528 to turn down the duty cycle of the pulse width modulation signal PWM1, for example by 25% each time. Counter 526 is reset after reaching a maximum count value, such as 3.

9 is a flow chart of a method of power control of a light source in accordance with one embodiment of the present invention. Figure 9 will be described in conjunction with Figures 4 and 5.

In step 902, a power converter, such as power converter 310, provides regulated power to power a source, such as LED chain 312.

In step 904, a switch monitoring signal is received, such as by a dimming controller 308. The switch monitor signal indicates the action of a power switch, such as power switch 304, located between the power source and the power converter.

In step 906, a dimming signal is generated based on the switch monitoring signal.

In step 908, a switch in series with the light source, such as switch Q16, is controlled in accordance with the dimming signal to adjust the regulated electrical energy provided by the power converter. In an embodiment employing an analog dimming mode, the dimming signal and a current monitoring signal representative of the magnitude of the source current are compared To adjust the power converter. In another embodiment employing a pulse dimming mode, the power converter is adjusted by controlling the duty cycle of a pulse width modulated signal with the dimming signal.

As described above, the present invention discloses a light source driving circuit that adjusts electric energy of a light source according to a switching signal indicating a power switch, such as a power switch fixed to a wall, and an action switch. The power of the source is provided by a power converter and is adjusted by a dimming controller by controlling a switch in series with the source.

The user can adjust the brightness of the light source by acting on a normal power switch, such as a disconnecting action, without having to use additional components, such as a specially designed switch with a dimming button, thereby saving cost.

FIG. 10 is a circuit diagram of a light source driving circuit 1000 in accordance with one embodiment of the present invention. Figure 10 will be described in conjunction with Figure 3. The same components in Fig. 10 as those in Figs. 3 and 4 have similar functions.

Light source drive circuit 1000 includes a power converter 310 coupled to a power source and LED chain 312 for receiving power from a power source and providing regulated power to LED chain 312. The dimming controller 1008 monitors the action of the power switch 304 between the power source and the light source driving circuit 1000 by the voltage on the 埠CLK. The dimming controller 1008 receives the dimming request signal and the dimming termination signal through the 埠CLK. The dimming request signal indicates a first set of actions of the power switch 304, the dimming termination signal indicating a second set of actions of the power switch 304. If the dimming request signal is received, the dimming controller 1008 continuously adjusts the adjusted electrical energy output by the power converter 310. If the dimming termination signal is received, the dimming controller 1008 stops adjusting the adjusted electrical energy output by the power converter 310. In other words, if the first set of actions of the power switch 304 is monitored, the dimming controller 1008 begins to continuously adjust the adjusted power output by the power converter 310 until the second set of power switches 304 is monitored. action. In one embodiment, dimming controller 1008 adjusts the regulated electrical energy output by power converter 310 by controlling control switch Q16 in series with LED chain 312.

FIG. 11 is a schematic structural view of the dimming controller 1008 of FIG. 10, which will be described in conjunction with FIG. The same components in Fig. 11 as those in Figs. 4, 5, and 10 have similar functions.

In the embodiment of FIG. 11, the structure of the dimming controller 1008 is similar to that of the dimming controller 308 of FIG. The difference is in the dimmer 1102 and the trigger monitoring unit 1106. In FIG. 11, the trigger monitoring unit 1106 receives the dimming request signal and the dimming termination signal through 埠CLK, and generates a signal EN to turn the clock generator 1104 on or off. The trigger monitoring unit 1106 also controls the conduction state of the switch Q27 connected to the LED chain 312.

In analog dimming mode, dimmer 1102 generates reference signal REF to adjust the power of LED chain 312. In the pulse dimming mode, the dimmer 1102 generates a control signal 538 to adjust the duty cycle of the pulse width modulation signal PWM1 to adjust the power of the LED chain 312. In the embodiment of FIG. 11, dimmer 1102 includes a clock generator 1104 coupled to trigger monitoring unit 1106 for generating a clock signal, a counter 1126 driven by a clock signal, and a digital to analog converter 528 coupled to counter 1126. . The dimmer 1102 also further includes a pulse width modulation signal generator 530 coupled to the digital to analog converter 528.

When the power switch 304 is turned "on" or "off", the trigger monitoring unit 1106 can detect a voltage rising edge or a falling edge at 埠CLK, respectively. For example, when the power switch 304 is turned off, the capacitor C10 is discharged to power the dimming controller 1108. The voltage across resistor R6 drops to zero, so that the trigger monitoring unit 1106 can detect a voltage falling edge on 埠CLK. Similarly, when the power switch 304 is turned on, the voltage across the resistor R6 rises to a preset voltage, thereby triggering the monitoring unit. 1106 can detect a rising voltage on 埠CLK. As previously mentioned, the trigger monitoring unit 1106 can monitor the action of the power switch 304, such as a turn-on or turn-off action, by the voltage on the 埠CLK.

In one embodiment, when the first set of actions of the power switch 304 is monitored, that is, the trigger monitoring unit 1106 receives the dimming request signal through the 埠CLK. When the second set of actions of the power switch 304 is monitored, that is, the trigger monitoring unit 1106 receives the dimming termination signal through the 埠CLK. In one embodiment, the first set of actions of the power switch 304 includes a first open action and a subsequent first turn-on action. In one embodiment, the second set of actions of the power switch 304 includes a second disconnect action and a second turn-on action thereafter.

If the trigger monitoring unit 1106 receives the dimming request signal, the dimming controller 1108 begins to continuously adjust the adjusted electrical energy output by the power converter 310. In the analog dimming mode, the dimming controller 1108 adjusts the adjusted electrical energy output by the power converter 310 by adjusting the voltage of the reference signal REF. In the pulse dimming mode, the dimming controller 1108 adjusts the adjusted electrical energy output by the power converter 310 by adjusting the duty cycle of the pulse width modulation signal PWM1.

If the trigger monitoring unit 1106 receives the dimming termination signal, the dimming controller 1108 stops adjusting the adjusted electrical energy output by the power converter 310.

FIG. 12 is a schematic diagram showing the operation of a light source driving circuit including the dimming controller 1008 shown in FIG. 11 according to an embodiment of the present invention. FIG. 12 will be described in conjunction with FIG. 10 and FIG.

In one embodiment, assume that the power switch 304 is off at the initial moment. When the power switch 304 is turned on by the user, the power converter 310 supplies power to the LED chain 312, which has an initial brightness. In the analog dimming mode, the initial luminance is determined by the initial voltage of the reference signal REF. set. In the pulse dimming mode, the initial brightness is determined by the initial duty cycle of the pulse width modulation signal PWM1, such as a 100% duty cycle. The reference signal REF and the pulse width modulation signal PWM1 are generated by the digital to analog converter 528 based on the count value of the counter 1126. Therefore, the initial voltage of REF and the initial duty cycle of PWM1 are determined by the initial count value of counter 1126, such as zero.

To adjust the brightness of the LED chain 312, the user can apply a first set of actions to the power switch 304. A dimming request signal is generated under the action of the first set of actions. In one embodiment, the first set of actions includes a first break action and a subsequent first switch action. As a result of this, the trigger monitoring unit 1106 monitors the voltage falling edge 1204 and the subsequent voltage rising edge 1206 at 埠CLK. In response to the dimming request signal, the trigger monitoring unit 1106 generates an EN signal having a high potential, thereby activating the clock generator 1104 to generate a clock signal. A counter 1126 driven by a clock signal changes its count value in response to each clock pulse of the clock signal. In the embodiment of Figure 12, the count value is incremented by the action of the clock signal. In one embodiment, the counter value is reset to zero when the counter 1126 reaches its preset maximum count value. In another embodiment, the count value is incremented until the counter 1126 reaches the preset maximum count value, and then the count value is decremented until the counter 1126 reaches the preset minimum count value.

In analog dimming mode, digital to analog converter 528 reads the count value from counter 1126 and lowers the voltage of reference signal REF in response to an increment of the count value. In the pulse dimming mode, the digital-to-analog converter 528 reads the count value from the counter 1126 and gradually decreases the duty cycle of the pulse width modulation signal PWM1 as the count value increases, for example, by 10% each time. Because the adjusted power output by the power converter 310 is determined by the voltage of the reference signal REF (in analog dimming mode) or by the duty cycle of the pulse width modulation signal PWM1 (in the pulse dimming mode), the LED chain The brightness of 312 can be adjusted accordingly.

Once the LED chain 312 reaches the desired brightness, the user terminates the brightness adjustment by applying a second set of actions to the power switch 304. A dimming termination signal is generated by the action of the second set of actions. In one embodiment, the second set of actions includes a second break action and a second turn-on action thereafter. As a result of this, the trigger monitoring unit 1106 monitors the voltage falling edge 1208 and the subsequent voltage rising edge 1210 at 埠CLK. Under the action of the dimming termination signal, the trigger monitoring unit 1106 generates an EN signal having a low potential, thereby turning off the clock generator 1104. The counter 1126 driven by the clock signal keeps its count value unchanged. In the analog dimming mode, the voltage of the reference signal REF will remain unchanged. In the pulse dimming mode, the duty cycle of the pulse width modulation signal PWM1 will remain unchanged. Therefore, the LED chain 312 will maintain the desired brightness unchanged.

13 is a flow chart 1300 of a method of power control of a light source in accordance with one embodiment of the present invention. FIG. 13 will be described in conjunction with FIG. 10 and FIG.

In step 1302, the regulated electrical energy output by the power converter, such as power converter 310, supplies power to a light source, such as LED chain 312.

In step 1304, a dimming request signal is received, such as by a dimming controller 1108. The dimming request signal indicates a first set of actions of a power switch, such as power switch 304, coupled between the power source and the power converter. In one embodiment, the first set of actions of the power switch includes a first open action and a subsequent first turn-on action.

In step 1306, the adjusted electrical energy output by the power converter is continuously adjusted, for example, by dimming controller 1108. In one embodiment, clock generator 1104 is enabled to drive counter 1126. A dimming signal, such as control signal 538 or reference signal REF, is generated based on the count value of counter 1126. In the analog dimming mode, the adjusted electrical energy output by the power converter is adjusted by comparing the reference signal REF with a current monitoring signal indicative of a flow through the source. The voltage of REF is determined by the count value. In the pulse dimming mode, the duty cycle of the pulse width modulation signal PWM1 is adjusted by the control signal 538 to the regulated power output by the power converter. The duty cycle of PWM1 is determined by the count value.

In step 1308, a dimming termination signal is received, such as by a dimming controller 1108. The dimming termination signal indicates a second set of actions of a power switch, such as power switch 304, coupled between the power source and the power converter. In one embodiment, the second set of actions of the power switch includes a second disconnect action and a second turn-on action thereafter.

In step 1310, if the dimming termination signal is received, the adjustment of the adjusted electrical energy output by the power converter is stopped. In one embodiment, clock generator 1104 is turned off such that counter 1126 maintains its count value unchanged. As a result, in the analog dimming mode, the voltage of the reference signal REF remains unchanged; in the pulse dimming mode, the duty cycle of the pulse width modulation signal PWM1 remains unchanged. Therefore, the light source can maintain the desired brightness.

FIG. 14A is a circuit diagram of a light source driving circuit 1400 in accordance with an embodiment of the present invention. Figure 14A will be described in conjunction with Figure 4. The same components in Fig. 14 as those in Figs. 3 and 4 have similar functions. Light source drive circuit 1400 is coupled to power supply VIN through power switch 304, for example, 220 VAC, 50 Hz, and coupled to LED light source 312. Figure 14B is a block diagram showing the structure of an embodiment of the power switch 304 of Figure 14A. In one embodiment, the power switch 304 is an ON/OFF switch placed on the wall. By switching element 1480 to the ON or OFF terminal, the conductive state of power switch 304 can be controlled by the user to be closed or open.

As shown in FIG. 14A, the light source driving circuit 1400 includes an AC/DC converter 306, a power converter 310, and a dimming controller 1408. The AC/DC converter 306 converts the input AC voltage VIN into an output DC voltage VOUT. Power converter 310 is coupled to an AC/DC converter 306, for receiving the output DC voltage VOUT, and providing output power to the LED light source 312. The dimming controller 1408 is coupled to the AC/DC converter 306 and the power converter 310 for monitoring the power switch 304 and adjusting the output power of the power converter 310 according to the action of the power switch 304, thereby controlling the brightness of the LED light source 312. .

In one embodiment, power converter 310 includes an inductor L1, a diode D4, a control switch Q16, a switch Q27, and a resistor R5. The dimming controller 1408 includes a plurality of turns, such as: 埠 HV_GATE, 埠 CLK, 埠 VDD, 埠 CTRL, 埠 MON, and 埠 GND. The 埠 of the dimming controller 1408 has a similar function as the corresponding 埠 of the dimming controller 308 described in FIG.

In operation, 埠CLK of dimming controller 1408 receives switch monitor signal 1450 to monitor power switch 304. Switch monitoring signal 1450 represents the conductive state of power switch 304, such as an ON/OFF state. Therefore, the dimming controller 1408 controls the switch Q27 by 埠HV_GATE and controls the switch Q16 by 埠CTRL, thereby controlling the dimming of the LED light source 312.

More specifically, in one embodiment, when power switch 304 is closed, dimming controller 1408 generates a signal on 埠HV_GATE, such as: logic high to close switch Q27, and 开关CTRL to generate switch control signal 1452 To close and open the control switch Q16. In one embodiment, control switch Q16 operates in a switch closed state and a switch open state. When the control switch Q16 is in the switch closed state, the switch control signal 1452 alternately closes and opens the control switch Q16. In addition, dimming controller 1408 receives an inductive signal 1454 indicative of current I _LED flowing through LED source 312 via 埠MON. When the sense signal 1454 indicates the rise of the current I _LED to the current threshold I _TH , the dimming controller 1408 turns off the control switch Q16. Therefore, when the control switch Q16 is closed, the current I _LED gradually becomes larger; when the control switch Q16 is turned off, the current I _LED gradually becomes smaller. In this manner, dimming controller 1408 determines the peak value of current I _LED and thereby controls the average value I _{AVERAGE of} current I _LED . When control switch Q16 is in the switch open state, switch control signal 1452 maintains control switch Q16 open to shut off current I _LED . In one embodiment, dimming controller 1408 determines the time ratio between the switch closed state and the switch open state to control the average value I _{AVERAGE of the} current I _LED .

In one embodiment, when power switch 304 is turned off, dimming controller 1408 generates a signal on 埠HV_GATE, such as a logic low to switch switch Q27. Therefore, the current I _LED flowing through the LED light source 312 drops to substantially zero amps to extinguish the LED light source 312.

In one embodiment, dimming controller 1408 receives a switch monitoring signal 1450 indicative of the conductive state of power switch 304 via 埠CLK. Accordingly, the dimming controller 1408 recognizes the action of the power switch 304 and provides a dimming request signal indicating the action. In one embodiment, the dimming controller 1408 provides a dimming request signal upon recognizing the opening action of the power switch 304; or the dimming controller 1408 provides a dimming request signal upon recognizing the closing action of the power switch 304. . In response to the dimming request signal, the dimming controller 1408 operates in an analog dimming mode, a burst dimming mode, or a hybrid dimming mode to control the LED by adjusting the closing/opening of the control switch Q16. Dimming of light source 312. For example, in analog dimming mode, dimming controller 1408 determines the peak value of current I _LED and maintains the time ratio between the closed state of the switch and the open state of the switch. In the burst dimming mode, the dimming controller 1408 determines the time ratio between the switch closed state and the switch open state and maintains the peak value of the current I _LED unchanged. In the hybrid dimming mode, the dimming controller 1408 determines the time ratio between the switch closed state and the switch open state and determines the peak value of the current I _LED . Therefore, when the switch Q27 is closed again (ie, the power switch 304 is closed again), the dimming controller 1408 adjusts the peak value of the current I _LED and/or the duration of the switch closed state and the switch open state, thereby adjusting the flow through the LED. The average current I _{AVERAGE of the} light source 312 is used to control the brightness of the LED light source 312.

An advantage of the above embodiment is that the dimming controller 1408 can adjust the average current I _AVERAGE over a relatively wide range by adjusting the duration of the current I _LED and the switch closed state and the switch open state. For example, if the maximum value I _MAX I _AVERAGE represented, then according to embodiments of the present invention, may I _AVERAGE I _MAX. 4% * 100% * variations within the scope of I _MAX. In the prior art, I _AVERAGE only varies from 20%*I _MAX to 100%*I _MAX . Therefore, with the technical solution provided by the embodiment of the present invention, the LED light source 312 can realize dimming in a wider range, and thus can be applied to a more energy-saving lamp, for example, a night light.

FIG. 15 is a block diagram showing the structure of the dimming controller 1408 of FIG. 14A. Figure 15 will be described in conjunction with Figures 5, 6, 7, and 14A. The same components in Fig. 15 as those of Figs. 5 and 14A have similar functions.

In the embodiment shown in FIG. 15, the dimming controller 1408 includes a start and low voltage lock (UVL) circuit 508, a pulse signal generator 504, a trigger monitoring unit 506, a dimmer 1502, a comparator 534, and an SR flip-flop. 522 and 524. The dimmer 1502 includes a reference signal generator 1506 for generating a reference signal REF. The dimmer 1502 further includes a pulse width modulation signal generator 1508 for generating a pulse width modulation signal PWM1. In conjunction with the description of FIG. 5, comparator 534 compares sense signal 1454 with reference signal REF to produce comparison signal COMP. Pulse signal generator 504 generates pulse signal 536 having a periodic pulse waveform. In one embodiment, when the pulse signal 536 is a logic one, the SR flip-flop 522 sets the pulse signal V522 to one; when the comparison signal COMP is a logic one (ie, when the sense signal 1454 rises to the reference signal REF), the SR triggers The 522 resets the pulse signal V522 to zero. The gate 524 receives the pulse signal V522 and the pulse width modulation signal PWM1, and accordingly generates a switch control signal 1452 to control the control switch Q16.

Assuming switch Q27 is closed, dimming controller 1408 controls current I _LED in a manner similar to that of dimming controller 308 described in Figures 6 and 7. In one embodiment, when the pulse width modulation signal PWM1 is in the first state, for example, PWM1 is logic 1, and the gate 524 alternately closes and opens the control switch Q16 according to the pulse signal V522. Thereby, the control switch Q16 operates in the switch closed state. In the switch closed state, the current ILED gradually rises when the control switch Q16 is closed, and gradually decreases when the control switch Q16 is turned off. Since the control switch Q16 is turned off when the sense signal 1454 rises to the reference signal REF, the reference signal REF determines the peak value of the current I _LED . When the pulse width modulation signal PWM1 is in the second state, for example, PWM1 is logic 0, and the gate 524 is turned off according to the hold control switch Q16. At this time, the control switch Q16 operates in the switch off state to cut off the current I _LED .

Therefore, the reference signal REF is used to determine the peak value of the current I _LED , and the duty cycle of the pulse width modulation signal PWM1 is used to determine the time ratio between the switch closed state and the switch open state. That is, the average current I _AVERAGE flowing through the LED light source 312 varies according to the duty cycle of the reference signal REF and the pulse width modulation signal PWM1. For example, when the voltage value V _{REF of the} reference signal REF rises, I _AVERAGE increases; when V _REF decreases, I _AVERAGE decreases. Further, when the duty cycle D _{PWM1 of the} pulse width modulation signal PWM1 becomes large, I _AVERAGE increases; when D _PWM1 becomes small, I _AVERAGE decreases.

The dimmer 1502 also includes a counter 1504 for providing a count value VALUE_1504. In one embodiment, reference signal generator 1506 is coupled to counter 1504 and determines the voltage value V _{REF of} reference signal REF based on count value VALUE_1504. The PWM generator 1508 is coupled to the counter 1504 and determines the duty cycle D _{PWM1 of the} pulse width modulation signal PWM1 based on the count value VALUE_1504.

Tables 1 and 2 above show an embodiment of the count value VALUE_1504, the voltage V _{REF ,} and the duty cycle D _PWM1 . In one embodiment, the counter 1504 is a 2-bit counter, and thus, the count value VALUE_1504 can be 0, 1, 2, or 3. V _MAX represents the maximum value of the reference signal REF. Specifically, as shown in Table 1, when the count value VALUE_1504 is 0, 1, 2, and 3, the reference signal REF has voltage values V _MAX , 50% * V _MAX , 20% * V _{MAX ,} and 20% * V, respectively. _MAX , and the duty cycle D _PWM1 is 100%, 100%, 100%, and 20%, respectively. As shown in Table 2, when the count value VALUE_1504 is 0, 1, 2, and 3, the reference signal REF has voltage values V _MA X, 50% * V _MAX , 30% * V _{MAX ,} and 20% * V _MAX , respectively, and The duty cycle D _PWM1 is 100%, 60%, 40% and 20% respectively. The count value VALUE_1504, voltage V _REF and duty cycle D _PWM1 may have other relationships and are not limited to the embodiments of Tables 1 and 2.

In one embodiment, if a dimming request signal is received, for example, indicating that the power switch 304 has performed a disconnect operation, the trigger monitoring unit 506 generates an enable signal 1510. The counter 1504 receives the enable signal 1510 and accordingly increases or decreases the count value VALUE_1504. Therefore, the reference signal generator 1506 determines the reference signal REF, for example, according to the data relationship of Table 1 or Table 2. The PWM generator 1508 determines the duty cycle of the PWM1, for example, according to the data relationship of Table 1 or Table 2.

Thus, dimming controller 1408 selectively operates in analog dimming mode, burst dimming mode, and mixed dimming mode. In the analog dimming mode, the dimming controller 1408 determines the value of the reference signal REF according to the count value of the counter 1504 to adjust the average value I _{AVERAGE of the} current I _LED ; at this time, the duty cycle of the PWM 1 remains unchanged. In the burst dimming mode, the dimming controller 1408 determines the duty cycle of the PWM1 according to the count value of the counter 1504 to adjust the average value I _{AVERAGE of the} current I _LED ; at this time, the value of the reference signal REF remains unchanged. In the mixed dimming mode, the dimming controller 1408 simultaneously determines the duty cycle of the PWM1 and the value of the reference signal REF according to the count value of the counter 1504 to adjust the average value I _{AVERAGE of the} current I _LED . Thereby, the brightness of the LED light source 312 is adjusted. The operation of dimming controller 1408 will be further described in Figures 16 and 17. The dimming controller 1408 can have other configurations and is not limited to the embodiment shown in FIG.

FIG. 16 is a signal diagram showing the light source driving circuit including the dimming controller 1408 of FIG. Figure 16 will be described in conjunction with Figures 14A and 15. Figure 16 depicts the voltage V _{CLK on}埠_CLK , the count value VALUE_1504 of the counter 1504, the voltage V _PWM1 of the pulse width modulation signal PWM1, the duty cycle D _{PWM1 of the} pulse width modulation signal _PWM1 , and the voltage of the reference signal REF. The value V _REF , the voltage V _{SENSE of the} sense signal 1454, and the average value I _{AVERAGE of the} current I _LED . In the embodiment shown in FIG. 16, the dimming controller 1408 sets the voltage value V _REF and the duty cycle D _PWM1 in accordance with the embodiment in Table 1 above.

At time t0, the power switch 304 is turned off. The count value VALUE_1504 is 0. According to Table 1, the duty cycle D _PWM1 is 100%, and the voltage value V _REF has a maximum value V _MAX . Since both the power switch 304 and the switch Q27 are turned off, the current I _LED is turned off, so the average current I _AVERAGE is zero amps.

At time t1, the rising edge of the voltage V _CLK indicates the closing action of the power switch 304. The dimming controller 1408 closes the switch Q27. Therefore, the current I _LED is controlled in accordance with the conduction state of the control switch Q16. At the time interval t1 to t2, the duty cycle D _PWM1 is 100%, and the voltage value V _REF has a maximum value V _MAX . Control switch Q16 operates in a closed state of the switch to alternately close and open. As shown in FIG. 16, when the control switch Q16 is closed, the voltage V _SENSE gradually rises; when the control switch Q16 is turned off, the voltage V _SENSE gradually decreases. Since the peak value of the voltage V _SENSE is equal to the maximum value V _{MAX of the} reference signal REF, the average current I _AVERAGE has a maximum value I _MAX .

At time t2, the falling edge of the voltage V _CLK indicates the off operation of the power switch 304. Switch Q27 is turned off to cut off the current I _LED . Thus, during the time interval from t2 to t3, the voltage V _SENSE drops to approximately zero volts and the average current I _AVERAGE drops to approximately zero amps.

In one embodiment, the dimming request signal is generated as the disconnection action of the power switch 304 is detected at time t2. The count value VALUE_1504 is increased from 0 to 1. Based on the embodiment of Table 1, dimming controller 1408 switches to analog dimming mode to adjust voltage V _REF to 50% * V _MAX and maintain duty cycle D _PWM1 to 100%.

At time t3, switch Q27 is closed again. Therefore, at the time interval from t3 to t4, the dimming controller 1408 controls the closing and opening of the control switch Q16 in accordance with the reference signal REF and the pulse width modulation signal PWM1. Therefore, the average current I _{AVERAGE is} adjusted to 50% * I _MAX .

At time t4, the falling edge of the voltage V _CLK indicates the off operation of the power switch 304. The count value VALUE_1504 is increased from 1 to 2. According to Table 1, the dimming controller 1408 operates in analog dimming mode to adjust the voltage V _REF to 20% * V _MAX and maintain the duty cycle D _PWM1 to 100%. Therefore, in the time interval from t5 to t6, the average current I _{AVERAGE is} adjusted to 20% * I _MAX .

At time t6, the falling edge of the voltage V _CLK indicates the off operation of the power switch 304. The count value VALUE_1504 is increased from 2 to 3. According to Table 1, dimming controller 1408 operates in burst dimming mode to maintain voltage V _REF at 20% * V _MAX and reduce duty cycle D _PWM1 to 20%. Therefore, in the time interval from t7 to t8, the power switch 304 is closed. At this time, when the voltage V _PWM1 has a first state, for example, a logic high potential, the voltage VSENSE ramps up and ramps down; when the voltage V _PWM1 has a second state, for example, a logic low, the voltage V _SENSE drops to zero volts. Therefore, in the time interval from t7 to t8, the average current I _{AVERAGE is} adjusted to 4% * I _MAX .

Therefore, in the embodiment shown in FIG. 16, the dimming controller 1408 first operates to adjust the average current I _AVERAGE from 100% * I _MAX to 20% * I _MAX in the analog dimming mode, and then operates in a burst. In the dimming mode, the average current I _{AVERAGE is} adjusted from 20% * I _MAX to 4% * I _MAX . An advantage of the embodiment of the present invention is that the average current I _{AVERAGE is} achieved at 100% * I _MAX and 4% * I _MAX by adjusting the duty cycle D _{PWM1 of the} pulse width modulation signal PWM1 and the voltage value V _{REF of the} reference signal REF. Adjustment within the scope. Thus, LED light source 312 is enabled to dim over a wider range. In addition, during a relatively wide range of dimming, the voltage V _REF remains greater than a voltage threshold, for example: 15% * V _MAX , the duty cycle D _PWM1 remains greater than a duty cycle threshold, for example: 10% . Thereby, the accuracy of the pulse width modulation signal PWM1 and the reference signal REF is not affected by adverse factors such as noise, thereby improving the dimming accuracy of the light source driving circuit 1400.

Figure 17 is a signal diagram showing the light source driving circuit including the dimming controller 1408 of Figure 15. Figure 17 will be described in conjunction with Figures 14A through 16. Figure 17 depicts the voltage V _{CLK on}埠_CLK , counter 1504 count value VALUE_1504, pulse width modulation signal PWM1 voltage V _PWM1 , pulse width modulation signal PWM1 duty cycle D _PWM1 , reference signal REF voltage value V _REF , the voltage of the sense signal 1454 V _SENSE , the average value of the current I _LED I _AVERAGE . In the embodiment shown in FIG. 17, dimming controller 1408 sets voltage value V _REF and duty cycle D _PWM1 in accordance with the embodiment in Table 1.

In the time interval between t0' and t2', the dimming controller 1408 has a similar operation between t0 and t2 as described in FIG. For example, in the time interval of t0' to t2', the count value VALUE_1504 is 0. According to Table 2, the duty cycle D _PWM1 is 100%, and the voltage value V _REF has a maximum value V _MAX . Therefore, between t1' and t2', the peak value of the voltage V _SENSE is equal to the maximum value V _{MAX of the} reference signal REF, and the average current I _AVERAGE has a maximum value I _MAX .

At time t2', the falling edge of the voltage V _CLK indicates the off operation of the power switch 304. Switch Q27 is turned off to cut off the current I _LED . Thus, during the time interval from t2' to t3', the voltage V _SENSE drops to approximately zero volts and the average current I _AVERAGE drops to approximately zero amps.

In one embodiment, since the disconnection action of the power switch 304 is detected at time t2', a dimming request signal is generated. The count value VALUE_1504 is increased from 0 to 1. Based on the embodiment of Table 2, the dimming controller 1408 switches to the mixed dimming mode to adjust the voltage V _REF to 50% * V _MAX and adjust the duty cycle D _PWM1 to 60%. Therefore, at the time interval t3' to t4', when the voltage _VPWM1 has the first state, for example, the logic high potential, the control switch Q16 operates in the switch closed state to alternately close and open. The peak value of the voltage VSENSE is equal to the voltage value V _{REF of the} reference signal _REF , ie 50% * V _MAX . Further, when the voltage V _PWM1 has the second state, for example, a logic low level, the control switch Q16 operates in the switch off state to cut off the current I _LED . Therefore, the average value I _{AVERAGE of the} current I _LED is equal to 30% * I _MAX .

At the time t4', the falling edge of the voltage V _CLK indicates the off operation of the power switch 304, and thus, the dimming request signal is generated. The count value VALUE_1504 is increased from 1 to 2. According to Table 2, the dimming controller 1408 operates in a mixed dimming mode to adjust the voltage V _REF to 30% * V _MAX and maintain the duty cycle D _PWM1 at 40%. Therefore, in the time interval from t5' to t6', the average current I _{AVERAGE is} adjusted to 12% * I _MAX .

At the time t6', the falling edge of the voltage V _CLK indicates the off operation of the power switch 304, and thus, the dimming request signal is generated. The count value VALUE_1504 is increased from 2 to 3. According to Table 2, the dimming controller 1408 operates in a mixed dimming mode to adjust the voltage V _REF to 20% * V _MAX and reduce the duty cycle D _PWM1 to 20%. Therefore, in the time interval from t7' to t8', the average current I _{AVERAGE is} adjusted to 4% * I _MAX .

Therefore, between t1' and t7', when the count value VALUE_1504 changes, the dimming controller 1408 operates in the mixed dimming mode. The advantage is that the average current I _AVERAGE is adjusted in the range of 100% * I _MAX and 4% * I _MAX by adjusting the duty cycle D _{PWM1 of the} pulse width modulation signal PWM1 and the voltage value V _{REF of the} reference signal REF. Thus, LED light source 312 is enabled to dim over a wider range. In addition, during a relatively wide range of dimming, the voltage V _REF remains greater than a voltage threshold, for example: 15% * V _MAX , the duty cycle D _PWM1 remains greater than a duty cycle threshold, for example: 10% . Thereby, the accuracy of the pulse width modulation signal PWM1 and the reference signal REF is not affected by adverse factors such as noise, thereby improving the dimming accuracy of the light source driving circuit 1400.

Figure 18 is a flow chart 1800 of a method of controlling dimming of an LED light source in accordance with an embodiment of the present invention. FIG. 18 will be described in conjunction with FIGS. 14A through 17. The specific steps covered in Figure 18 are merely examples. That is, the present invention is applicable to other reasonable processes or steps for improving FIG.

In step 1802, a sense signal (eg, sense signal 1454) and a reference signal (eg, reference signal REF) representing a current flowing through the LED light source are compared to generate a pulse signal, For example: pulse signal V522.

In step 1804, when the pulse width modulation signal (eg, PWM1) is in the first state, the current flowing through the LED light source is controlled according to the pulse signal.

In step 1806, when the pulse width modulation signal is in the second state, the current flowing through the LED source is turned off.

In step 1808, the value of the reference signal and the duty cycle of the pulse width modulation signal are adjusted according to the dimming request signal to adjust the average current flowing through the LED light source.

In one embodiment, the counter value of the counter is adjusted based on the dimming request signal. The duty cycle value and the duty cycle of the pulse width modulation signal are determined according to the count value of the counter. If the count value changes from the first value to the second value, the first mode (eg, analog dimming mode), the second mode (burst dimming mode), or the third mode (mixed dimming mode) is selected. In the first mode, the value of the reference signal is adjusted and the duty cycle of the pulse width modulation signal is maintained. In the second mode, the duty cycle of the pulse width modulation signal is adjusted and the value of the reference signal is kept constant. In the third mode, the value of the reference signal is adjusted and the duty cycle of the pulse width modulation signal is adjusted.

FIG. 19 is a circuit diagram of a light source driving circuit 1900 in accordance with an embodiment of the present invention. The same components in Fig. 19 as those in Figs. 3 and 4 have similar functions. Figure 19 will be described in conjunction with Figures 3 and 4. Light source drive circuit 1900 is coupled to power supply V _IN (e.g., 110/120 volts, 60 Hz AC) via power switch 304 and provides output power to LED source 312. In one embodiment of the invention, the power switch 304 can be an ON/OFF switch placed on the wall as shown in Figure 14B. The conductive state of the power switch 304 can be controlled by the user to be closed or open.

The light source driving circuit 1900 includes an AC/DC converter 306, a power converter 310, and a dimming controller 1908. The AC/DC converter 306 converts the input AC voltage VIN into an output DC voltage V _OUT . In the example of FIG. 19, the AC/DC converter 306 includes a bridge rectifier having diodes D1, D2, D7, and D8, and further includes a filter having a diode D10 and a capacitor C9. Power converter 310 is coupled to AC/DC converter 306 for receiving an output DC voltage V _OUT and providing regulated power to LED source 312. In one embodiment, power converter 310 includes an inductor L1, a diode D4, a switch Q27, a control switch Q16, and a current inductor R5. Dimming controller 1908 is coupled between AC/DC converter 306 and power converter 310. The dimming controller 1908 monitors the action of the power switch 304, such as closing or opening, and correspondingly controls the regulated power supplied by the power converter 310 to the LED source 312 to control the brightness of the LED source 312. The dimming controller 1908 includes a plurality of turns, for example, 埠HV_GATE, 埠CLK, 埠VDD, 埠GND, voltage control 埠CTRL, 埠RT, 埠MON, and current control 埠CS. Where 埠 VDD, 埠 GND, 埠 RT, and 埠 MON are similar to the corresponding operations of the dimming controller 1408 of FIG. 14A.

In one embodiment, dimming controller 1908 receives a switch monitoring signal 1450 indicating the action (closed or open) of power switch 304 at 埠CLK. In one embodiment, dimming controller 1908 controls switch Q27 based on switch monitoring signal 1450. Specifically, when switch monitor signal 1450 indicates that power switch 304 is off, dimming controller 1908 generates a signal, such as a logic low signal, at 埠HV_GATE to open switch Q27. Therefore, the current I _LED flowing through the LED light source 312 is lowered to 0 amps to turn off the LED light source 312. When switch monitor signal 1450 indicates that power switch 304 is closed, dimming controller 1908 generates a signal, such as a logic high signal, at 埠HV_GATE to close switch Q27. The dimming controller 1908 controls the current I _LED flowing through the LED light source 312 based on the signals of the voltage control 埠 CTRL and the current control 埠 CS.

In one embodiment, the dimming controller 1908 monitors the signal 1450 based on the switch. A dimming request signal indicating the action of the power switch 304 is determined. In one embodiment, when the switch monitoring signal 1450 indicates that the power switch 304 is off, the dimming controller 1908 receives the dimming request signal. When the power switch 304 is reclosed, the dimming controller 1908 adjusts the average current flowing through the LED light source 312 to adjust the brightness of the LED light source 312 in accordance with the dimming request signal.

The dimming controller 1908 is operable in the first mode and the second mode to adjust the average current of the LED light source 312. Current I _LED represents the current flowing through LED light source 312 as described below. In the first mode, the current I _LED is represented by I _LED1 . In the second mode, the current I _LED is represented by I _LED2 .

When the dimming controller 1908 is operating in the first mode, the voltage control 埠CTRL of the dimming controller 1908 provides a pulse signal 1952 to control the control switch Q16 to alternately operate in a first state (eg, a closed state) and a second state ( For example, disconnected state). Therefore, the current I _LED1 flowing through the LED light source 312 changes in accordance with the state of the control switch Q16. In one embodiment, during the closing of control switch Q16, current I _LED1 flows through LED source 312, switch Q27, control switch Q16, and resistor R5 to ground, so current I _LED1 increases. During the control switch Q16 is turned off, the current flowing through the LED light source 312 I _LED1 and diode D4, so that the current I _LED1 reduced. According to an embodiment of the present invention, the average current flowing through the LED light source 312 can be adjusted by controlling the control switch Q16 in the analog dimming mode, the pulse dimming mode, or the combined dimming mode, and the specific dimming method will be combined. Figure 20 is described in detail.

When the dimming controller 1908 is operating in the second mode, the dimming controller 1908 provides a control signal 1954, such as digit 0, in the voltage control 埠CTRL to maintain the control switch Q16 in the off state. Therefore, the current I _LED1 is cut off. Additionally, dimming controller 1908 turns on current I _LED2 flowing through LED source 312 and current control 埠CS.

Advantageously, the dimming controller 1908 achieves a relatively wide dimming range by selecting to operate in at least the first mode and the second mode. For example, if I _MAX indicates the maximum value of the average current I _AVERAGE of the LED source 312, the dimming controller 1908 can operate in the first mode to adjust the average current I _{AVERAGE of the} current I _LED1 to vary over a wide range, such as 4%*I _MAX varies from 100%*I _MAX . Additionally, dimming controller 1908 can also operate in the second mode to adjust the average current I _AVERAGE to a lower value. For example, dimming controller 1908 sets current I _LED2 to a constant value of 1%*I _MAX . In other words, the LED light source 312 is darker in the second mode than in the first mode. Therefore, in energy-saving applications, such as night lights, there will be more advantages. In addition, the current I _LED2 in the second mode is a substantially constant value which does not change due to the closing or opening of the control switch Q16. Therefore, the light emitted by the LED light source 312 is not affected by the switching noise of the control switch Q16, thereby enhancing the dimming stability of the LED light source 312.

Figure 20 is a block diagram showing the structure of the dimming controller 1908 of Figure 19 in accordance with an embodiment of the present invention. Figure 20 will be described in conjunction with Figures 15 and 19. The same components in Fig. 20 as those in Figs. 15 and 19 have similar functions. In the example of FIG. 20, dimming controller 1908 includes a startup and low voltage lockout circuit 508, a pulse signal generator 504, a trigger monitoring unit 506, a dimmer 2002, a driver 2010, a switch 2008, and a current source 2006.

In one embodiment, trigger monitoring unit 506 receives switch monitoring signal 1450 via 埠CLK. The trigger monitoring unit 506 determines a dimming request signal indicating that the power switch 304 is turned off according to the switch monitor signal 1450. If a dimming request signal is received, the trigger monitoring unit 506 generates an enable signal 1510.

The dimmer 2002 includes a counter 1504, a reference signal generator 1506, a pulse width modulation signal generator 1508, and a mode selection module 2004. Counter 1504 is provided according to enable The signal 1510 changes the count value VALUE_1504. In one embodiment, counter 1504 increments count value VALUE_1 504 based on enable signal 1510. In another embodiment, the counter 1504 decreases the count value VALUE_1 504 based on the enable signal 1510.

The mode selection module 2004 selects the operation mode of the dimming controller 1908 from the first mode and the second mode based on the count value VALUE_1504. In one embodiment, the count value VALUE_1 504 indicates the desired brightness value of the LED light source 312. The desired brightness value corresponds to the target current value I _TARGET of the average current I _AVERAGE of the LED light source 312 . Tables 3 and 4 show examples of the correspondence between the count value VALUE_1504 of the counter 1504, the target current value I _TARGET, and the operation mode of the dimming controller 1908. In the example of Table 3, the count value VALUE_1504 may be 0, 1, and 2, indicating that the target current value I _TARGET is 100% * I _MAX , 30% * I _{MAX ,} and 1% * I _MAX , respectively, where I _MAX represents the average The maximum value of the current I _AVERAGE . In the example of Table 4, the count value VALUE_1504 may be 0, 1, and 2, indicating that the target current value I _TARGET is 1% * I _MAX , 30% * I _{MAX ,} and 100% * I _{MAX , respectively} .

The mode selection module 2004 compares the count value VALUE_1504 with a threshold to select an operating mode. For example, according to the examples of Tables 3 and 4, the threshold value is set to 1. In the example of Table 3, when the count value VALUE_1504 is equal to or smaller than 1, the mode selection module 2004 selects the first mode. When the count value VALUE_1504 is greater than 1, the mode selection module 2004 selects the second mode. In the example of Table 4, when the count value VALUE_1504 is equal to or greater than 1, the mode selection module 2004 selects the first mode, and when the count value VALUE_1504 is less than 1, the mode selection module 2004 selects the second mode. Therefore, in the examples of Tables 3 and 4, when the target current value I _{TARGET of the} average current I _AVERAGE is relatively high (e.g., 30% * I _MAX and 100 * I _MAX ), the first mode is selected. In addition, when the target current value I _{TARGET of the} average current I _AVERAGE is relatively low (eg, 1% * I _MAX ), the second mode is selected.

The mode selection module 2004 controls the switch 2008, the reference signal generator 1506, and the pulse width modulation signal generator 1508 to adjust the average current I _AVERAGE according to the selected mode of operation. More specifically, in one embodiment, current source 2006 produces a substantially constant current I _LED2 . When the dimming controller 1908 is operating in the first mode, the mode selection module 2004 turns off the switch 2008 to cut off the current I _LED2 , and controls the reference signal generator 1506 to generate the reference signal REF, and controls the pulse width modulation signal generator. 1508 generates a pulse width modulation signal PWM1. In one embodiment, the driver 2010 generates a pulse signal 1952 based on the reference signal REF and the pulse width modulation signal PWM1 to control the control switch Q16.

In one embodiment, the driver 2010 includes a comparator 534, an SR flip flop 522, and a AND gate 524. When operating in the first mode, the operating principle of the driver 2010 is similar to the corresponding components in the dimming controller 1408 of FIG. As described above with respect to FIG. 15, comparator 534 compares sense signal 1454 with reference signal REF to produce comparison signal COMP. The pulse signal generator 504 generates a pulse signal 536 having a periodic pulse waveform. In one embodiment, SR pulse 522 sets pulse signal V ₅₂₂ to a digital bit when pulse signal 536 is a digital one. When the comparison signal COMP is a digital one (ie, when the sense signal 1454 reaches the reference signal REF), the SR flip-flop sets the pulse signal V522 to a digital zero. The gate 524 receives the pulse signal V ₅₂₂ and the pulse width modulation signal PWM1, and generates a pulse signal 1952 on the voltage control 埠CTRL to control the control switch Q16. Therefore, when the pulse width modulation signal PWM1 is in the first state (eg, digit 1), the waveform of the pulse signal 1952 is the same as the waveform of the pulse signal V ₅₂₂ , that is, switching between the digit 1 and the digit 0 according to the comparison signal COMP. When the pulse width modulation signal PWM1 is in the second state (e.g., digit 0), the pulse signal 1952 is held at the digit 0. According to the related description above with respect to FIG. 15, the reference signal REF determines the peak value of the current I _LED1 . The duty cycle of the pulse width modulation signal PWM1 determines the ratio of the closing time and the opening time of the control switch Q16. Therefore, by adjusting the value of the reference signal REF and/or the duty cycle of the pulse width modulation signal PWM1, the dimmer 2002 can operate in an analog dimming mode, a pulse dimming mode, or a combined dimming mode to adjust the LED light source 312. The average current I _AVERAGE .

According to the example in Table 3, when the count value VALUE_1504 is 0, the dimming controller 1908 operates in the first mode, the value of the reference signal REF is V _REF0 , and the duty cycle of the pulse width modulation signal PWM1 is D _{PWM0 .} . When the count value VALUE_1504 changes from 0 to 1, the dimming controller 1908 remains operating in the first mode, and the target current value of the average current I _AVERAGE changes from 100% * I _MAX to 30% * I _MAX . If the dimmer 2002 operates in the analog dimming mode, the value of the reference signal REF is adjusted to 30% * V _REF0 , and the duty cycle of the pulse width modulation signal PWM1 remains as D _PWM0 . If the dimmer 2002 operates in the pulse dimming mode, the value of the reference signal REF is maintained at V _REF0 , and the duty cycle of the pulse width modulation signal PWM1 is adjusted to 30% * D _PWM0 . If the dimmer 2002 operates in the combined dimming mode, the value of the reference signal REF and the duty cycle of the pulse width modulation signal PWM1 will change. For example, the value of the reference signal REF is adjusted to 50% * V _REF0 , pulse width The duty cycle of the modulation signal PWM1 is adjusted to 60% * D _PWM0 . Using any of the three dimming modes (ie, analog dimming mode, pulse dimming mode, and combined dimming mode), the average current I _{AVERAGE is} changed from 100% * I _MAX to 30% * I _MAX to complete Dimming control in the first mode.

When the dimming controller 1908 is operating in the second mode, as shown in Table 3, when the count value VALUE_1504 changes from 1 to 2, the dimming controller 1908 generates a control signal 1954 at CTRL to turn off the control switch Q16. . More specifically, the mode selection module 2004 controls the pulse width modulation signal generator 1508 to maintain the pulse width modulation signal PWM1 in the second state (eg, digit 0). Gate 524 generates a control signal 1954 (e.g., a digital 0 signal) to maintain the voltage control 埠 CTRL voltage at a low potential. Therefore, the current I _LED1 flowing through the LED light source 312 is cut off.

Additionally, in one embodiment, current source 2006 produces a substantially constant current I _LED2 . The mode selection module 2004 generates a switch control signal 2012 to close the switch 2008. If the switch Q27 is turned on after the power switch 304 is closed, the circuit of the current I _LED2 is turned on. Therefore, the current I _LED2 flows through the LED light source 312, the current control 埠CS, and the switch 2008 to the ground. Among them, "substantially constant current I _LED2 " means that the value of current I _LED2 is limited to a certain range, so that non-ideal current ripple generated by circuit components can be ignored. Advantageously, circuit currents of LED source 312 can be reduced or eliminated because current I _{LED2 is} unaffected by one or more switches, such as power switch 304 and/or control switch Q16. Therefore, the dimming stability of the light source driving circuit 1900 is improved. The dimming controller 1908 can have other configurations and is not limited to the example of FIG.

21 is a signal diagram of a light source driving circuit including the dimming controller 1908 of FIG. 19 in accordance with an embodiment of the present invention. 21 will be described with reference to FIG. 19 and FIG. 20. FIG. 21 shows the voltage V _{CLK of}埠_CLK , the count value VALUE_1504 of the counter 1504, the voltage V _PWM1 of the pulse width modulation signal PWM1, and the pulse width modulation signal PWM1. The duty cycle D _PWM1 , the current I _LED flowing through the LED source 312 and the average current I _{AVERAGE of the} current I _LED . In the example of FIG. 19, the dimming controller 1908 determines the mode of operation according to Table 3 and controls the average current I _{AVERAGE of the} LED source 312.

At time t0", the power switch 304 is turned off. The dimming controller 1908 turns off the switch Q27. The count value VALUE_1504 is 0. According to Table 3, the mode selection module 2004 selects the first mode, and the target current value of the average current I _AVERAGE is 100%*I _MAX Therefore, the pulse width modulation signal generator 1508 adjusts the duty cycle D _PWM1 of the pulse width modulation signal _PWM1 to 100%, and the reference signal generator 1506 controls the reference signal REF to adjust the current I _LED . The peak value is I _PEAK (the maximum value of the peak current). At time t1", the voltage V _{CLK of 埠CLK} has a rising edge indicating the closing operation of the power switch 304, and the average current I _AVERAGE is adjusted to 100%*I _MAX . During t1" to t2", the average current I _{AVERAGE is} maintained at 100%*I _MAX .

At time t2", the voltage V _CLK has a falling edge indicating that the power switch 304 is turned off. The switch Q27 is turned off to cut off the current I _LED . Therefore, during t2" to t3", the current I _LED drops to 0 amps. The average current I _AVERAGE drops to 0 amps.

In one embodiment, at time t2", voltage V _CLK has a falling edge indicating that power switch 304 is off, receiving a dimming request signal. Count value VALUE_1 504 is increased from 0 to 1. According to Table 3, average current I The target current value of _AVERAGE is adjusted to 30%*I _MAX . During t2" to t4", mode selection module 2004 remains in the first mode, and in the example of Figure 21, dimmer 2002 operates in combined dimming mode, The pulse width modulation signal generator 1508 adjusts the duty cycle D _PWM1 to 60%, and the reference signal generator 1506 controls the reference signal REF to adjust the peak value of the current I _LED to 50%*I _PEAK . At time t3", 埠CLK The voltage V _CLK has a rising edge indicating that the power switch 304 is closed, and the average current I _{AVERAGE is} adjusted to 30% * I _MAX . During t3" to t4", the average current I _{AVERAGE is} maintained at 30%*I _MAX .

At time t4", the voltage V _CLK has a falling edge indicating that the power switch 304 is turned off, and receives the dimming request signal. Accordingly, the count value VALUE_1504 is increased from 1 to 2. According to Table 3, the target of the average current I _AVERAGE The current value is adjusted to 1%*I _MAX , and the mode selection module 2004 selects the second mode. Therefore, the mode selection module 2004 generates the switch control signal 2012 to close the switch 2008. During t4" to t5", because of the power switch 304 and Switch Q27 is open, so both current I _LED and average current I _AVERAGE are 0 amps.

At time t5", the voltage V _{CLK of 埠CLK} has a rising edge indicating the closing operation of the power switch 304. Since the switch Q27 is turned on after the power switch 304 is closed, and the switch 2008 is closed at time t4", the path of the current I _LED2 is turned on. Was connected. In one embodiment, current I _LED2 is equal to 1%*I _MAX . Therefore, during t5" to t6", the average current I _{AVERAGE is} maintained at 1%*I _MAX .

Therefore, during t1" to t6", the dimming controller 1908 selects the operation mode from the first mode and the second mode in accordance with the count value VALUE_1504. Advantageously, dimming controller 1908 can achieve a relatively wide dimming range, such as from 100%*I _MAX to 1%*I _MAX . The operation and operation of the dimming controller 1908 are not limited to the example of FIG. In another embodiment, during the second mode, the dimming controller 1908 can provide another current (eg, a smaller constant current value of 0.01 * I _MAX ) through the LED source 312 and the current control 埠CS. Therefore, the brightness of the LED light source 312 can be lower to achieve a wider dimming range. In addition, the current I _LED2 is a substantially constant value that does not change in accordance with the closing and opening actions of the control switch Q16. Therefore, the LED light source 312 is not affected by the noise of the control switch Q16, and the dimming stability of the LED light source 312 is enhanced.

Figure 22 illustrates a dimming controller (e.g., dimming control) in accordance with an embodiment of the present invention. A flow chart of a method of controlling LED light source dimming performed by the controller 1908). Figure 22 will be described in conjunction with Figures 19-21. The specific steps covered in Figure 22 are merely examples. That is, the present invention is applicable to other reasonable processes or steps for improving FIG.

In step 2202, a power converter, such as power converter 310, provides regulated electrical energy to a light source, such as LED light source 312.

In step 2204, a switch monitoring signal is received. The switch monitoring signal indicates the action of a power switch (such as power switch 304) connected between the power source and the power converter.

In step 2206, the operating mode is selected to be the first mode or the second mode according to the switch monitoring signal. In one embodiment, the counter value of the counter changes when a switch monitoring signal indicating a power switch off operation is received, such as from a first value to a second value. The count value is compared with a threshold value (such as 1), and the operation mode is selected according to the comparison result.

In step 2208, when the operating mode is selected to be the first mode, the control switch (eg, control switch Q16) operates in a first state (eg, a closed state) and a second state (eg, a disconnected) according to a pulse signal (eg, pulse signal 1952). status). In one embodiment, the first current flowing through the LED light source (eg, current I _LED1 ) is increased when the control switch is in the first state, and the first current flowing through the LED light source is decreased when the control switch is in the second state. . In one embodiment, when the operating mode is selected to be the first mode, a reference signal (such as reference signal REF) and a pulse width modulation signal (such as pulse width modulation signal PWM1) are generated. In the first mode, an induced signal indicative of a first current flowing through the LED source is compared to a reference signal. When the pulse width modulation signal is in the first state (e.g., digit 1), the control switch is closed and turned off according to the comparison result. When the pulse width modulation signal is in the second state (eg, digit 0), the control switch is turned off and the first current is decreased. In one embodiment, in the first mode, when the count value changes, the value of the reference signal and/or the duty cycle of the pulse width modulation signal is adjusted to adjust the brightness of the LED light source.

In step 2210, when the operating mode is selected to be the second mode, the first current (eg, current I _LED1 ) is turned off according to a control signal (eg, control signal 1954). In one embodiment, in the second mode, the pulse width modulation signal is maintained in a second state (e.g., digit 0) to generate a control signal (e.g., a digital zero signal) to turn off the first current.

In step 2212, when the operating mode is selected to be the second mode, the second current flowing through the LED source 312 is turned on. In one embodiment, the second current is a substantially constant current (eg, current I _LED2 ). In one embodiment, current I _{LED2 is} provided by a current source, such as current source 2006. When the second mode is selected, the mode selection module 2004 generates a switch control signal 2012 to close the switch 2008 in series with the current source 2006.

FIG. 23A is a schematic diagram of a light source driving circuit 2300 in accordance with an embodiment of the present invention. In one embodiment, the light source includes a first illuminating element (eg, a first LED chain 2308) and a second illuminating element (eg, a second LED chain 2310). The second LED chain 2310 can have a different color temperature value than the first LED chain 2308, for example, the first LED chain 2308 has a first color temperature value and the second LED chain 2310 has a second color temperature value. A power switch 304 coupled between the power source V _IN and the light source drive circuit 2300 selectively couples the power source V _IN to the light source drive circuit 2300. In one embodiment, the power switch 304 can be a power switch placed on a wall.

The light source driving circuit 2300 includes an AC/DC converter 306 for converting an AC input voltage V _IN from a power source into a DC voltage V _DC , coupled to the AC/DC converter 306 and a light source (eg, the first LED chain 2308 and the A DC/DC converter 2302, a color temperature controller 2306, a light source (eg, a first LED chain 2308 and a second LED chain 2310), a first control switch 2312, a second control switch 2314, and a current between the two LED chains 2310) Monitor 2316. Wherein, the AC/DC converter 306 and the DC/DC converter 2302 constitute a power converter coupled between the power source and the light source for receiving power from the power source and providing the adjusted power to the light source. The DC/DC converter 2302 is for receiving a DC voltage V _DC from the AC/DC converter 306 and providing a regulated output voltage V _OUT to the light source (eg, the first LED chain 2308 and the second LED chain 2310). The DC/DC converter 2302 includes a transformer 2304 having a primary side winding and a secondary side winding. A color temperature controller 2306 is coupled between the primary side winding of the transformer 2304 and the light source (eg, the first LED chain 2308 and the second LED chain 2310) for receiving a switch monitoring signal indicative of operation of the power switch 304 (eg, a disconnect operation) TS, and adjusts the color temperature of the light source (eg, the first LED chain 2308 and the second LED chain 2310) based on the switch monitoring signal TS. As shown in FIG. 23A, the color temperature controller 2306 generates a first control signal CTR1 and a second control signal CTR2 according to the switch monitoring signal TS to control the first LED chain 2308 and the second LED chain 2310, respectively.

The first control signal CTR1 selectively turns on the first control switch 2312 coupled between the color temperature controller 2306 and the first LED chain 2308 such that the color temperature of the light source is adjusted to a first color temperature value. The second control signal CTR2 selectively turns on the second control switch 2314 coupled between the color temperature controller 2306 and the second LED chain 2310 to adjust the color temperature of the light source to a second color temperature value. More specifically, if the first control signal CTR1 turns on the first control switch 2312 coupled between the color temperature controller 2306 and the first LED chain 2308, the current I _LED1 flows through the first LED chain 2308 and the color temperature of the light source is Adjusted to a first color temperature value; if the second control signal CTR2 turns on the second control switch 2314 coupled between the color temperature controller 2306 and the second LED chain 2310, the current I _LED2 flows through the second LED chain 2310 and the light source The color temperature is adjusted to the second color temperature value. The color temperature controller 2306 also receives a current monitoring signal SEN indicating a current value flowing through the light source (eg, the value of the current I _LED1 or the current I _LED2 ) from the current monitor 2316, and generates a drive signal DRV according to the current monitoring signal SEN. The drive signal DRV controls the input voltage of the primary side winding of the transformer 2304, thereby adjusting the output voltage V _{OUT of the} DC/DC converter 2302.

FIG. 23B is a circuit diagram of a light source driving circuit 2300 according to an embodiment of the present invention. The light source driving circuit 2300 is powered by a power source V _IN (for example, 110/120 V ac, 60 Hz) via a power switch 304. In one embodiment, the AC/DC converter 306 of Figures 23B and 4 has the same structure. AC/DC converter 306 is coupled to DC/DC converter 2302 and color temperature controller 2306. The current monitor 2316 can be a current detecting resistor R5.

The DC/DC converter 2302 receives the input voltage V _D C from the AC/DC converter 306 and provides a regulated output voltage V _OUT to the source (eg, the first LED chain 2308 and the second LED chain 2310). In the example of FIG. 23B, the DC/DC converter 2302 includes a transformer 2304, a control switch Q23, a diode D4, and a capacitor C6. The transformer 2304 includes a primary side winding 2305 for receiving an input voltage V _DC from the AC/DC converter 306, a secondary winding 2307 for supplying an output voltage V _OUT to the first LED chain 2308 and the second LED chain 2310, and a magnetic A core 2325 and an auxiliary winding 2309 for supplying a voltage to the color temperature controller 2306. The transformer 2304 shown in Figure 23B includes three windings by way of example and not limitation. In other embodiments, the transformer 2304 can include other different numbers of windings. In the embodiment shown in FIG. 23B, the control switch Q23 coupled to the primary side winding 2305 is external to the color temperature controller 2306. In other embodiments, the control switch Q23 can also be integrated into the interior of the color temperature controller 2306.

Color temperature controller 2306 is coupled to primary side winding 2305 and auxiliary winding 2309 of transformer 2304. The color temperature controller 2306 can be a flyback pulse width modulation (PWM) controller for generating a PWM signal to selectively turn on the control switch Q23 in series with the primary side winding 2305, and by adjusting the duty cycle of the PWM signal. The output voltage of the transformer 2304 is adjusted. For example but Without limitation, the color temperature controller 2306 includes 埠CLK, 埠PWM, 埠VDD, 埠CS, 埠FB, 埠SW1, and 埠SW2.

The color temperature controller 2306 receives the switch monitoring signal TS indicating the on state (for example, the on or off state) of the power switch 304 at 埠CLK, and generates the first control signal CTR1 (at 埠SW1) according to the switch monitoring signal TS. And a second control signal CTR2 (at 埠SW2) to control the first LED chain 2308 and the second LED chain 2310, respectively. More specifically, in one embodiment, if the switch monitor signal TS indicates that the power switch 304 is turned "on" for the first time, the color temperature controller 2306 generates a first control signal CTR1 to turn on the first control switch 2312 and generate a second control. Signal CTR2 to turn off second control switch 2314, therefore, current I _LED1 flows through first LED chain 2308 without current flowing through second LED chain 2310; if switch monitoring signal TS indicates that power switch 304 is off and for a predetermined period of time Once again, the color temperature controller 2306 generates a first control signal CTR1 to turn off the first control switch 2312 and generate a second control signal CTR2 to turn on the second control switch 2314, so that no current flows through the first LED chain. 2308, current I _LED2 flows through the second LED chain 2310. Because the second LED chain 2310 can have a different color temperature than the first LED chain 2308, the color temperature controller 2306 can adjust the color temperature of the light source based on the switch monitoring signal TS.

The 埠FB receives a current monitoring signal SEN indicating the value of the current I _LED1 or the current I _LED2 from the current monitor 2316. The 埠CS receives a monitor signal LPSEN indicating the current flowing through the primary side winding 2305. The color temperature controller 2306 receives the current monitor signal SEN and the monitor signal LPSEN, and generates a drive signal DRV at the 埠PWM to control the control switch Q23 to adjust the output voltage VOUT of the DC/DC converter 2302.

The color temperature controller 2306 controls the conduction state of the control switch Q23 by generating a drive signal DRV at the 埠PWM according to the current monitoring signal SEN and the monitor signal LPSEN (for example, turning on Or disconnected state). More specifically, the voltage of the current monitoring signal SEN can be compared with the voltage of the reference signal indicating the target current value flowing through the light source, and the voltage of the monitoring signal LPSEN can be compared with the voltage of another reference signal indicating the target current value, If any of the comparison results indicates that the transient current value flowing through the light source is greater than the target current value, the color temperature controller 2306 reduces the duty cycle of the drive signal DRV and vice versa. In one embodiment, if the drive signal DRV is in a first state (eg, a logic high), the control switch Q23 is turned "on", current flows through the primary side winding 2305, and the magnetic core 2325 performs energy storage. If the drive signal DRV is in the second state (eg, logic low), the control switch Q23 is turned off, and the diode D4 coupled to the secondary side winding 2307 is forward biased to transmit the energy stored in the core 2325. The secondary side winding 2307 is released to the capacitor C6 and the light source. Therefore, the power of the light source (eg, the first LED chain 2308 and the second LED chain 2310) can be adjusted according to the drive signal DRV.

埠 VDD is coupled to the auxiliary winding 2309. In one embodiment, an energy storage unit (eg, capacitor C5) coupled between 埠VDD and ground supplies power to color temperature controller 2306 when power switch 304 is turned off.

Advantageously, in response to the opening operation of the power switch 304 in the primary side circuit, the light source in the secondary side circuit is turned on after the power switch 304 is turned on again within a predetermined period of time after the opening operation of the power switch 304 (eg, The color temperature of the first LED chain 2308 and the second LED chain 2310) is adjusted by the color temperature controller 2306 to a target color temperature value.

Figure 24 is a block diagram showing the structure of the color temperature controller 2306 of Figure 23B in accordance with an embodiment of the present invention. Figure 24 will be described in conjunction with Figures 20 and 23B. The same components in Fig. 24 as those in Figs. 20 and 23B have similar functions. In the example of FIG. 24, color temperature controller 2306 includes a startup and low voltage lock (UVL) circuit 508, driver 2410, control unit 2420, determination Unit 2431 and inverter 2433.

The driver 2410 is configured to receive a current monitoring signal SEN indicating a value of a current flowing through the first LED chain 2308 or the second LED chain 2310 from the current monitor 2316, and generate a driving signal DRV according to the current monitoring signal SEN. In one embodiment, the driver 2410 includes an error amplifier 2411, a sawtooth signal generator 2413, a comparator 2415, and a pulse width modulation signal generator 2417. The error amplifier 2411 generates an error signal VEA based on the reference signal REF and the current monitoring signal SEN, the reference signal REF indicating a target current value of the light source (eg, the first LED chain 2308 or the second LED chain 2310). Error amplifier 2411 receives current monitoring signal SEN at 埠FB, which indicates the value of current ILED1 or current ILED2 from current monitor 2316. The error signal VEA is used to adjust the value of the current ILED1 flowing through the first LED chain 2308 or the value of the current ILED2 flowing through the second LED chain 2310 to a target current value. The sawtooth wave signal generator 2413 generates a sawtooth wave signal SAW. The comparator 2415 is coupled to the error amplifier 2411 and the sawtooth signal generator 2413 for comparing the error signal VEA with the sawtooth signal SAW and generating an output signal to the pulse width modulation signal generator 2417. The monitor signal LPSEN is received by the 埠CS indicating the current flowing through the primary side winding 2305. The pulse width modulation signal generator 2417 is coupled to the comparators 2415 and 埠CS, and generates a drive signal DRV based on the output signal of the comparator 2415 and the monitor signal LPSEN to control the state of the switch Q23. In one embodiment, if the voltage of the monitor signal LPSEN is greater than a voltage of another reference signal (not shown, such as may be built into the pulse width modulation signal generator 2417) indicating the target current value, then the flow is indicated. The current of the primary side winding 2305 is greater than the target current value, and the pulse width modulation signal generator 2417 reduces the duty cycle of the drive signal DRV, and vice versa.

When the voltage of the current monitoring signal SEN is greater than the voltage of the reference signal REF, the value indicating the current I _LED1 flowing through the first LED chain 2308 or the current I _LED2 flowing through the second LED chain 2310 is greater than the value determined by the reference signal REF. The target current value, the driver 2410 reduces the duty cycle of the drive signal DRV according to the current monitor signal SEN to reduce the output voltage of the DC/DC converter 2302. Similarly, when the voltage of the current monitoring signal SEN is less than the voltage of the reference signal REF, the value indicating the current I _LED1 flowing through the first LED chain 2308 or the current I _LED2 flowing through the second LED chain 2310 is less than the reference signal The target current value determined by REF, the driver 2410 increases the duty cycle of the drive signal DRV according to the current monitor signal SEN to increase the output voltage of the DC/DC converter 2302.

The determining unit 2431 detects the power state of the color temperature controller 2306 and generates a first determination signal VDD_L and a second determination signal VDD_H based on the power state of the color temperature controller 2306. The color temperature controller 2306 adjusts the color temperature of the light source based on the first determination signal VDD_L, the second determination signal VDD_H, and the switch monitoring signal TS. For example, if the voltage at the 埠VDD of the color temperature controller 2306 is less than the reset threshold voltage (eg, 4V), the first decision signal VDD_L has a first state (eg, a logic high potential); if the color temperature controller 2306 If the voltage at VDD is greater than the reset threshold voltage (eg, 4V), then the first decision signal VDD_L has a second state (eg, a logic low); if the voltage at the 埠VDD of the color temperature controller 2306 is less than enabled With a threshold voltage (eg, 10V), the second decision signal VDD_H has a first state (eg, a logic low); if the voltage at the 埠VDD of the color temperature controller 2306 is greater than the enable threshold voltage (eg, 10V) Then, the second determination signal VDD_H has a second state (for example, a logic high potential).

The control unit 2420 is configured to generate the first control signal CTR1 and the second control signal CTR2 according to the switch monitoring signal TS, the first determination signal VDD_L, and the second determination signal VDD_H to respectively control the first LED chain 2308 and the second LED chain 2310. In one embodiment, the control unit 2420 includes a timer 2421, a first D-type flip-flop 2423, a second D-type flip-flop 2425, a first AND gate 2427, and a second AND gate 2429. The timer 2421 receives the switch monitor signal TS and starts timing when the switch monitor signal TS has a falling edge. The timer 2421 also generates the pulse signal TS_DE after a predefined time interval Δt of each falling edge of the switch monitor signal TS. The pulse signal TS_DE is coupled to the input 埠CLK of the first D-type flip-flop 2423, and the switch monitor signal TS is coupled to the input 埠CLK of the second D-type flip-flop 2425. The input 埠D1 of the first D-type flip-flop 2423 is coupled to its output埠 And the output 埠Q1 of the first D-type flip-flop 2423 is coupled to the input 埠D2 of the second D-type flip-flop 2425.

The input 埠R of the first D-type flip-flop 2423 and the second D-type flip-flop 2425 are both coupled to the output 埠 of the inverter 2433, and the input 埠 of the inverter 2433 is coupled to the decision unit 2431. If the voltage at the 埠VDD of the color temperature controller 2306 is less than the reset threshold voltage (eg, 4V), the first decision signal VDD_L is at a logic high level, then the first D-type flip-flop 2423 and the second D-type positive and negative The device 2425 is reset by the inverter 2433, and therefore, the output 埠Q1 of the first D-type flip-flop 2423 and the output 埠Q2 of the second D-type flip-flop 2425 are both reset to a logic low level, and The output of the first D-type flip-flop 2423埠 And the output of the second D-type flip-flop 2425 Both are reset to logic high.

The output of the second decision signal VDD_H and the second D-type flip-flop 2425 Both are coupled to the first AND gate 2427. The first AND gate 2427 generates a first control signal CTR1 to control the first control switch 2312 and the current I _LED1 flowing through the first LED chain 2308. The second decision signal VDD_H and the output 埠Q2 of the second D-type flip-flop 2425 are both coupled to the second AND gate 2429. The second AND gate 2429 generates a second control signal CTR2 to control the second control switch 2314 and the current I _LED2 flowing through the second LED chain 2310. In this manner, color temperature controller 2306 can adjust the color temperature of the light source in response to the opening operation of power switch 304.

Fig. 25 is a signal waveform diagram of a light source driving circuit including the color temperature controller shown in Fig. 24. 25 shows the switch monitor signal TS, the pulse signal TS_DE, the first decision signal VDD_L, the second decision signal VDD_H, the voltage at the input 埠D1, the voltage at the output 埠Q1, the voltage at the output 埠Q2, the first control Signal waveforms of the signal CTR1 and the second control signal CTR2. Figure 25 will be described in conjunction with Figures 23B and 24.

At time t0, the power switch 304 is turned "on". At time t1, the switch monitor signal TS changes from a first state (eg, a logic low) to a second state (eg, a logic high), and the voltage at VDD increases to a reset threshold voltage (eg, 4V) And the first determination signal VDD_L is changed from the first state (for example, a logic high level) to the second state (for example, a logic low level). At time t2, the voltage at VDD increases to enable the threshold voltage (eg, 10V) and the second decision signal VDD_H changes from the first state (eg, logic low) to the second state (eg, logic high) Potential). The output 埠Q1 of the first D-type flip-flop 2423 and the output 埠Q2 of the second D-type flip-flop 2425 are both logic low during the time interval from time t0 to time t2. Since the second determination signal VDD_H received by the first AND gate 2227 and the second AND gate 2429 is logic low, the first control signal CTR1 and the second control signal CTR2 are also logic low. After the time t2, since the second determination signal VDD_H changes to a logic high level, the first control signal CTR1 also changes to a logic high level. Thus, the first control switch 2312 is turned "on" and the current I _LED1 begins to flow through the first LED chain 2308. At time t3, the power switch 304 is turned off, and the voltage at the 埠VDD of the color temperature controller 2306 begins to drop. As described above, once the switching monitor signal TS has a falling edge, the pulse signal TS_DE can be generated after the predefined time interval Δt. At time t4, in response to the rising edge of the pulse signal TS_DE, the input 埠D1 of the first D-type flip-flop 2423 changes from a logic high level to a logic low level, and the output 埠Q1 of the first D-type flip-flop 2423 The logic low changes to a logic high. At time t5, the voltage at 埠VDD is lowered to enable the threshold voltage (eg, 10V), and the second decision signal VDD_H is changed from the second state (eg, logic high) to the first state (eg, logic low) Potential). Therefore, since the second determination signal VDD_H received by the first AND gate 2227 and the second AND gate 2429 is at a logic low level, the first control signal CTR1 and the second control signal CTR2 are also both logic low.

At time t6, a rising edge of the switch monitor signal TS indicates that the power switch 304 is turned "on" again. The time interval from time t3 to time t6 is less than a predetermined (prescribed) time interval (eg, t6 minus t3 < 3 seconds) to maintain the voltage at 埠 VDD above the reset threshold voltage (eg, 4V) and first The determination signal VDD_L remains at a logic low level. In response to the rising edge of the switch monitor signal TS, the output 埠Q2 of the second D-type flip-flop 2425 changes from a logic low level to a logic high level, and its output 埠 Change from logic high to logic low. Similar to the time interval from time t1 to time t2, the time interval from time t6 to time t7, the first control signal CTR1 and the second control signal CTR2 are both logic low. After time t7, the voltage at VDD increases above the enable threshold voltage, the second decision signal VDD_H changes to a logic high level, and the second control signal CTR2 also changes to a logic high level, the second control switch 2314 Turned on and current I _LED2 begins to flow through the second LED chain 2310. Then, the power switch 304 is turned off again, and at time t8, the voltage at VDD is lowered to the enable threshold voltage (for example, 10 V). The signal waveform in the time interval from time t8 to time t10 is similar to the signal waveform in the time interval from time t0 to time t5. At time t9, the first control switch 2312 is turned "on" and the current I _LED1 begins to flow through the first LED chain 2308.

Therefore, the color temperature controller 2306 alternately turns on the first control switch 2312 and the second control switch 2314 in response to the off operation of the power switch 304, since the second LED chain 2310 can have a different color temperature than the first LED chain 2308, The color temperature controller 2306 can adjust the color temperature of the light source in response to the opening operation of the power switch 304.

Figure 26 is a diagram showing signal waveforms of a light source driving circuit including the color temperature controller shown in Figure 24 according to another embodiment of the present invention. 26 shows the switch monitor signal TS, the pulse signal TS_DE, the first decision signal VDD_L, the second decision signal VDD_H, the voltage at the input 埠D1, the voltage at the output 埠Q1, the voltage at the output 埠Q2, the first control Signal waveforms of the signal CTR1 and the second control signal CTR2. Figure 26 will be described in conjunction with Figures 23B, 24 and 25.

The waveform in the time interval from the time t0 to the time t6' is similar to the waveform in the time interval from the time t0 to the time t6 in Fig. 25. At time t7', the power switch 304 is turned "on" again. The time interval from the time t3 to the time t7' is greater than the predetermined time interval (e.g., t7' minus t3 > 3 seconds). Therefore, at time t6', the voltage at 埠VDD is lowered to the reset threshold voltage (for example, 4V), and the first determination signal VDD_L is changed from the logic low level to the logic high level, and the output 埠Q1 and the output 埠Q2 are both Reset to logic low. Since the second determination signal VDD_H received by the first AND gate 2227 and the second AND gate 2429 is logic low, the first control signal CTR1 and the second control signal CTR2 are also logic low.

At time t8', the switch monitor signal TS changes from a first state (eg, a logic low) to a second state (eg, a logic high), and the voltage at VDD increases to a reset state. The limit voltage (eg, 4V), and the first determination signal VDD_L changes from a first state (eg, a logic high potential) to a second state (eg, a logic low potential). At time t9', the voltage at VDD increases to enable the threshold voltage (eg, 10V), and the second decision signal VDD_H changes from the first state (eg, logic low) to the second state (eg, Logic high). The signal waveform in the time interval from the time t7' to the time t9' is similar to the signal waveform in the time interval from the time t0 to the time t2. After the time t9', the voltage at 埠VDD is increased above the enable threshold voltage, the second decision signal VDD_H is changed to a logic high level, and the first control signal CTR1 is also changed to a logic high level. Then, the first control switch 2312 is turned on and the current ILED1 begins to flow through the first LED chain 2308.

As shown in FIG. 25, if the switch monitor signal TS indicates that the time interval between the off operation of the power switch 304 and the next turn-on operation is less than a predetermined time interval (for example, 3 seconds), the color temperature controller 2306 responds to the power switch. The next turn-on operation of 304 changes the color temperature of the light source (eg, first LED chain 2308 and second LED chain 2310) from a first color temperature value to a second color temperature value. More specifically, in the example of FIG. 25, during the first time interval (eg, the time interval from time t2 to time t5), the first control signal CTR1 is at a logic high level, and the first LED chain 2308 is turned on. The second LED chain 2310 is turned off to adjust the color temperature of the light source to a first color temperature value; during a second time interval different from the first time interval (eg, a time interval from time t7 to time t8), second The control signal CTR2 is at a logic high level, the first LED chain 2308 is turned off, and the second LED chain 2310 is turned on so that the color temperature of the light source is adjusted to the second color temperature value. Therefore, the color temperature controller 2306 changes the color temperature of the light source from the color temperature of the first LED chain 2308 to the color temperature of the second LED chain 2310 by alternately turning on the first control switch 2312 and the second control switch 2314. However, as shown in FIG. 26, if the switch monitor signal TS indicates the time between the off operation of the power switch 304 and the next turn-on operation The interval is greater than the predetermined time interval, and the color temperature controller 2306 resets the color temperature of the light source to a preset color temperature value in response to the next turn-on operation of the power switch 304. In the example of FIG. 26, the preset color temperature value may be a color temperature value of the first LED chain 2308, for example, a color temperature value set by the factory; the preset color temperature value is not limited to the color temperature value shown in the example of FIG.

27 is a flow chart 2700 of a method of controlling the color temperature of a light source in accordance with an embodiment of the present invention. Figure 27 will be described in conjunction with Figures 23A-26. The specific steps covered in FIG. 27 are merely examples, that is, the present invention is applicable to steps that perform various other steps or that improve the steps expressed in FIG.

In step 2702, a drive circuit (eg, light source drive circuit 2300) receives power from a power source and is directed by a power converter (eg, AC/DC converter 306 and transformer 2304) to a light source (eg, first LED chain 2308 and second LED) Chain 2310) provides regulated electrical energy.

In step 2704, a switch monitor signal is received, the switch monitor signal TS (eg, the switch monitor signal received by the color temperature controller 2306) indicating operation of a power switch (eg, power switch 304) coupled between the power source and the power converter. .

In step 2706, the color temperature of the light source is adjusted based on the switch monitoring signal TS. For example, during a first time interval (eg, a time interval from time t2 to time t5 in FIG. 25), color temperature controller 2306 can generate first control signal CTR1 to turn on the first LED chain having the first color temperature value. 2308, and generating a second control signal CTR2 to turn off the second LED chain 2310 having the second color temperature value such that the color temperature of the light source is adjusted to the first color temperature value; during the second time interval different from the first time interval (For example, at time intervals from time t7 to time t8 in FIG. 25), color temperature controller 2306 may generate first control signal CTR1 to turn off first LED chain 2308, and generate second control signal CTR2 to turn on second LED chain 2310 so that the color temperature of the light source is adjusted to The second color temperature value.

Accordingly, the drive circuit of an embodiment of the present invention can control the light source (eg, the first LED chain 2308 and the second according to a switch monitoring signal indicating operation of a power switch (eg, an on/off switch placed on the wall) The color temperature of the LED chain 2310), and the power of the light source provided by the DC/DC converter can be adjusted by the color temperature controller by controlling the switches of the primary side winding of the transformer coupled in series to the DC/DC converter. Therefore, the user can adjust the color temperature of the light source by turning on/off the power switch operation (for example, the disconnect operation), thereby avoiding the use of additional components (such as a specially designed switch with an adjustment button) to adjust the light source. Color temperature, which saves costs.

The above description is exemplified based on an embodiment of an LED chain. However, embodiments in accordance with the invention may also be applied to other types of light sources. In other words, embodiments of the invention are not limited to LED light sources and are equally applicable to other types of light sources.

The wording and expressions used herein are for the purpose of illustration and description, and are not intended to be Various modifications are possible within the scope of the claims. Other modifications, variations, and alternatives may also be present. Accordingly, the claims are intended to cover all such equivalents.

304‧‧‧Power switch

306‧‧•AC/DC converter

2300‧‧‧Light source drive circuit

2302‧‧‧DC/DC Converter

2304‧‧‧Transformers

2305‧‧‧ primary winding

2306‧‧‧Color temperature controller

2307‧‧‧secondary winding

2308‧‧‧First LED chain

2309‧‧‧Auxiliary winding

2310‧‧‧Second LED chain

2312‧‧‧First control switch

2314‧‧‧Second control switch

2316‧‧‧ Current monitor

2325‧‧‧ magnetic core

Claims (20)

A light source driving circuit for driving a light source having a color temperature, the light source driving circuit comprising: a power converter coupled between a power source and the light source, receiving an electric energy from the power source and providing a light source to the light source The adjusted power; and a color temperature controller coupled to the power converter, receiving a switch monitoring signal indicating an operation of coupling a power switch between the power source and the power converter, and monitoring based on the switch The signal adjusts a color temperature of the light source. The light source driving circuit of claim 1, wherein the light source comprises: a first light emitting element having a first color temperature value and a second light emitting element having a second color temperature value, the color temperature controller comprising: a control unit, configured to generate a first control signal and a second control signal according to the switch monitoring signal, wherein the first control signal is selectively coupled to be coupled between the color temperature controller and the first light emitting element a first control switch to adjust the color temperature of the light source to the first color temperature value; the second control signal selectively turning on a second coupled between the color temperature controller and the second light emitting element The switch is controlled such that the color temperature of the light source is adjusted to the second color temperature value. The light source driving circuit of claim 2, wherein the control unit comprises: a timer that receives the switch monitoring signal, the timer starts counting when a falling edge of the switch monitoring signal occurs, and the falling edge a pulse signal is generated after a predefined time interval; a first D-type flip-flop receives the pulse signal; and a second D-type flip-flop is coupled to the first D-type flip-flop and receives the pulse And a switch monitoring signal; wherein the first control signal and the second control signal are generated based on an output signal of the second D-type flip-flop. According to the light source driving circuit of claim 1, wherein the color temperature controller comprises: a determining unit, detecting a power state of the color temperature controller and generating a first determination signal and a second determination signal based on the power state of the color temperature controller, the color temperature controller based on the first determination signal, the first The second decision signal and the switch monitor signal adjust the color temperature of the light source. The light source driving circuit of claim 1, wherein the color temperature control is performed if the switch monitoring signal indicates that a time interval between an off operation and a next on operation of the power switch is less than a predetermined time interval The color temperature of the light source is adjusted from a first color temperature value to a second color temperature value in response to the next turn-on operation of the power switch. The light source driving circuit of claim 5, wherein the light source comprises: a first light emitting element having the first color temperature value and a second light emitting element having the second color temperature value, the color temperature controller generating a first control signal and a second control signal adjust the color temperature of the light source, when the first control signal is coupled to a first control switch coupled between the color temperature controller and the first light emitting element, a first current flows through the first light emitting element and the color temperature of the light source is adjusted to the first color temperature value; when the second control signal is coupled to a one coupled between the color temperature controller and the second light emitting element When the second control switch, a second current flows through the second light emitting element and the color temperature of the light source is adjusted to the second color temperature value. The light source driving circuit of claim 1, wherein the color temperature is determined if the switch monitoring signal indicates that a time interval between an off operation and a next on operation of the power switch is greater than a predetermined time interval The controller resets the color temperature of the light source to a predetermined color temperature value in response to the next turn-on operation of the power switch. The light source driving circuit of claim 1, wherein the power converter comprises: an AC/DC converter and a transformer, the transformer comprising a primary winding, a secondary winding, and an auxiliary winding, the primary side a winding coupled to the AC/DC converter and used to pass the intersection A current/DC converter receives the electrical energy from the power source, the secondary side winding is configured to provide the adjusted electrical energy to the light source, the auxiliary winding is configured to supply power to the color temperature controller, and the power switch is coupled to the power source and Between the AC/DC converters. The light source driving circuit of claim 1, wherein the color temperature controller is configured to receive a current monitoring signal indicating a current value flowing through the light source, and control the adjustment provided to the light source according to the current monitoring signal Electrical energy. A color temperature controller includes: a driving unit that receives a current monitoring signal indicating a current value flowing through a light source, and generates a driving signal according to the current monitoring signal to control a power converter to provide an adjusted power to the a light source; and a control unit coupled to the driving unit, receiving a switch monitoring signal indicating an operation of a power switch, and adjusting a color temperature of the light source based on the switch monitoring signal, wherein the power switch is coupled to the power source and Between the power converters. The color temperature controller of claim 10, wherein the light source comprises: a first light emitting element having a first color temperature value and a second light emitting element having a second color temperature value, the control unit monitoring according to the switch The signal generates a first control signal and a second control signal, the first control signal selectively turning on a first control switch coupled between the color temperature controller and the first light emitting element to enable the light source The color temperature is adjusted to the first color temperature value; the second control signal selectively turns on a second control switch coupled between the color temperature controller and the second light emitting element to cause the color temperature of the light source to be Adjust to the second color temperature value. The color temperature controller according to claim 11 , wherein the control unit comprises: a timer, receiving the switch monitoring signal, and opening when a falling edge of the switch monitoring signal occurs Starting a timing, generating a pulse signal after a predefined time interval of the falling edge; a first D-type flip-flop receiving the pulse signal; and a second D-type flip-flop coupled to the first D-type a flip-flop and receiving the switch monitoring signal; wherein the first control signal and the second control signal are generated based on an output signal of the second D-type flip-flop. The color temperature controller of claim 10, wherein the color temperature controller further comprises: a determining unit that detects a power state of the color temperature controller and generates a first determination signal based on the power state of the color temperature controller And a second determination signal, the color temperature controller adjusting the color temperature of the light source based on the first determination signal, the second determination signal, and the switch monitoring signal. The color temperature controller according to claim 10, wherein the color temperature controller is if the switch monitoring signal indicates that a time interval between an off operation and a next on operation of the power switch is less than a predetermined time interval The color temperature of the light source is adjusted from a first color temperature value to a second color temperature value in response to the next turn-on operation of the power switch. The color temperature controller of claim 14, wherein the light source comprises: a first light emitting element having the first color temperature value and a second light emitting element having the second color temperature value, the color temperature controller generating a a first control signal and a second control signal to adjust the color temperature of the light source. When the first control signal is coupled to a first control switch coupled between the color temperature controller and the first light emitting element, a first current flows through the first light emitting element and the color temperature of the light source is adjusted to the first color temperature value; when the second control signal is coupled to a one coupled between the color temperature controller and the second light emitting element When the second control switch, a second current flows through the second light emitting element and the color temperature of the light source is adjusted to the second color temperature value. A color temperature controller according to claim 10, wherein if the switch monitoring signal indicates that a time interval between an off operation and a next on operation of the power switch is greater than a predetermined time At the time interval, the color temperature controller resets the color temperature of the light source to a preset color temperature value in response to the next turn-on operation of the power switch. A method for controlling a color temperature of a light source, comprising: receiving a power from a power source and providing a regulated power to a light source by a power converter; receiving a power switch coupled to the power source and the power converter a switch monitor signal for operation; and adjusting a color temperature of the light source based on the switch monitor signal. The method for controlling the color temperature of a light source according to claim 17, wherein the step of adjusting the color temperature of the light source based on the switch monitoring signal comprises: if the switch monitoring signal indicates that an off operation of the power switch is turned on and off A time interval between operations is less than a predetermined time interval, and the color temperature of the light source is adjusted from a first color temperature value to a second color temperature value in response to the next turn-on operation of the power switch. The method for controlling the color temperature of a light source according to claim 17, wherein the step of adjusting the color temperature of the light source based on the switch monitoring signal comprises: if the switch monitoring signal indicates that an off operation of the power switch is turned on and off A time interval between operations is greater than a predetermined time interval, and the color temperature of the light source is reset to a predetermined color temperature value in response to the next turn-on operation of the power switch. The method for controlling a color temperature of a light source according to claim 17, wherein the step of adjusting a color temperature of the light source based on the switch monitoring signal comprises: generating a first control signal to have a first during a first time interval a first light-emitting element of color temperature value, and generating a second control signal to turn off a second light-emitting element having a second color temperature value such that the color temperature of the light source is adjusted to the first color temperature value; Generating the first control signal during a second time interval of the first time interval to Disconnecting the first light emitting element and generating the second control signal to turn on the second light emitting element such that the color temperature of the light source is adjusted to the second color temperature value.