JP6104511B2 - Controller, system, and method for controlling dimming of a light source - Google Patents

Description

The present invention relates to a controller, system, and method for controlling dimming of a light source.
RELATED APPLICATIONS This application is a continuation-in-part of U.S. Patent Application No. 12 / 316,480, filed December 12, 2008, which is a U.S. Patent Application No. 12 / 415,028 filed March 31, 2009. Which are both continuation-in-part applications, both of which are fully incorporated herein by reference. This application is also a continuation-in-part of US patent application Ser. No. 12 / 761,681, filed Apr. 16, 2010, which is incorporated herein by reference in its entirety.

  In recent years, light sources such as light emitting diodes (LEDs) have been improved due to technological advances in materials and manufacturing processes. LEDs have relatively high efficiency, long life, and vivid colors and can be used in various industries including automobiles, computers, telecommunications, military, consumer goods and the like. One example is an LED lamp that uses LEDs to replace conventional light sources such as electrical filaments.

  FIG. 1 shows a schematic diagram of a conventional LED driving circuit 100. The LED drive circuit 100 uses the LED array 106 as a light source. LED string 106 includes a group of LEDs connected in series. The power converter 102 converts the input voltage Vin into a desired output DC voltage Vout in order to supply power to the LED string 106. A switch 104 coupled to the power converter 102 can enable or disable the input voltage Vin to the LED string 106 and thus can turn on or off the LED lamp. The power converter 102 receives the feedback signal from the current sensing resistor Rsen and adjusts the output voltage Vout to cause the LED string 106 to generate a desired light output. One drawback of this solution is that the desired light output is predetermined. During operation, the light output of the LED string 106 is set to a predetermined level and cannot be adjusted by the user.

  FIG. 2 shows a schematic diagram of another conventional LED driving circuit 200. The power converter 102 converts the input voltage Vin into a desired output DC voltage Vout in order to supply power to the LED string 106. A switch 104 coupled to the power converter 102 can enable or disable the input voltage Vin to the LED string 106 and thus can turn on or off the LED lamp. The LED string 106 is coupled to a linear LED current regulator 208. The operational amplifier 210 in the linear LED current regulator 208 compares the reference signal REF with the current monitoring signal from the current sensing resistor Rsen, generates a control signal, and adjusts the resistance value of transistor Q1 in linear mode To do. Accordingly, the LED current passing through the LED string 106 can be adjusted accordingly.

  In this solution, in order to control the light output of the LED string 106, the user can use a dedicated device, such as a specially designed switch to adjust a button or switch, that can receive a remote control signal, It may be necessary to adjust the signal REF.

  In one embodiment, the controller that controls dimming of the LED light source includes a control terminal and a dimming control circuit coupled to the control terminal. The control terminal provides a drive signal that controls a control switch coupled to the LED light source, thereby controlling dimming of the LED light source. The dimming control circuit generates a drive signal according to a set of operations of a power switch that transfers an AC signal. The dimming control circuit further adjusts the drive signal by counting multiple waves of the AC signal to control dimming of the LED light source.

  The features and advantages of the claimed embodiments will become apparent upon reading the following detailed description with reference to the drawings, in which like numerals indicate like parts.

It is the schematic of the conventional LED drive circuit. It is the schematic of another conventional LED drive circuit. 1 is a block diagram of a light source driving circuit according to an embodiment of the present invention. FIG. 1 is a schematic diagram of a light source driving circuit according to an embodiment of the present invention. FIG. 5 is a diagram showing a configuration of a dimming controller of FIG. 4 according to an embodiment of the present invention. It is a figure which shows the signal waveform in the analog dimming mode by one Embodiment of this invention. It is a figure which shows the signal waveform in the burst dimming mode by one Embodiment of this invention. FIG. 6 is a diagram illustrating an operation of a light source driving circuit including the dimming controller of FIG. 5 according to an embodiment of the present invention. 4 is a flowchart of a method for adjusting power of a light source according to an embodiment of the present invention. 1 is a schematic diagram of a light source driving circuit according to an embodiment of the present invention. FIG. 11 is a diagram illustrating a configuration of a dimming controller of FIG. 10 according to an embodiment of the present invention. FIG. 12 is a diagram illustrating an operation of a light source driving circuit including the dimming controller of FIG. 11 according to an embodiment of the present invention. 4 is a flowchart of a method for adjusting power of a light source according to an embodiment of the present invention. 1 is a schematic diagram of an example LED light source driving system according to an embodiment of the present invention. FIG. 14B is an example of the power switch of FIG. 14A, according to one embodiment of the present invention. FIG. 14B is a block diagram of an example of the dimming controller of FIG. 14A, according to one embodiment of the present invention. FIG. 16 is a block diagram of an example of the dimmer of FIG. 15, according to an embodiment of the present invention. It is an example of the figure which shows operation | movement of the LED light source drive system by one Embodiment of this invention. It is an example of the figure which shows operation | movement of the LED light source drive system by one Embodiment of this invention. 1 is a schematic diagram of an example LED light source driving system according to an embodiment of the present invention. FIG. 20 is a block diagram of an example of the dimming controller of FIG. 19 according to one embodiment of the present invention. 1 is a block diagram of an example LED light source driving system according to an embodiment of the present invention. FIG. 6 is a flowchart of an example method for controlling dimming of an LED light source, according to an embodiment of the present invention.

  Reference will now be made in detail to the embodiments of the present invention. When the invention is described with reference to these embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to protect alternatives, modifications and equivalents that may be included within the spirit and scope of the invention as defined by the appended claims. .

  Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the invention may be practiced without these specific details. In other instances, well-known methods, procedures, elements, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present invention.

FIG. 3 shows an example of a block diagram of a light source driving circuit 300 according to an embodiment of the present invention. In one embodiment, the light source driving circuit 300 includes an AC / DC converter 306 that converts an AC input voltage V _IN from a power source to a DC voltage V _OUT , and a power source that selectively couples the power source to the light source driving circuit 300. Power switch 304 coupled to AC / DC converter 306, power converter 310 coupled to AC / DC converter 306 supplying regulated power to LED string 312 and operation of power switch 304 are shown. A dimming controller 308 coupled to the power converter 310 that receives the switch monitoring signal and adjusts the adjusted power from the power converter 310 in response to the switch monitoring signal and senses the LED current passing through the LED string 312 Current sensor 314. In one embodiment, the power switch 304 may be a connect / disconnect switch that is mounted on the wall.

During operation, the AC / DC converter 306 converts the input AC voltage V _IN to the output DC voltage V _OUT . The power converter 310 receives the DC voltage V _OUT and supplies adjusted power to the LED string 312. The current sensor 314 generates a current monitoring signal indicating the level of LED current passing through the LED string 312. The dimming controller 308 monitors the operation of the power switch 304, receives a current monitoring signal from the current sensor 314, controls the power converter 310 in response to the operation of the power switch 304, and adjusts the power of the LED string 312 Can operate to. In one embodiment, the dimming controller 308 operates in an analog dimming mode and adjusts the power of the LED string 312 by adjusting a reference signal indicating the peak value of the LED current. In another embodiment, the dimming controller 308 operates in a burst dimming mode and adjusts the power of the LED string 312 by adjusting the duty cycle of the pulse width modulation (PWM) signal. By adjusting the power of the LED string 312, the light output of the LED string 312 can be adjusted accordingly.

  FIG. 4 shows an example of a schematic diagram of a light source driving circuit 400 according to an embodiment of the present invention. FIG. 4 is described in combination with FIG. Elements having the same reference numerals as in FIG. 3 have similar functions and will not be described in detail here.

  The light source drive circuit 400 includes a power converter 310 (shown in FIG. 3) that couples to the power supply, receives power from the power supply, and couples to the LED string 312 to provide regulated power to the LED string 312. In the example of FIG. 4, power converter 310 may be a buck converter including inductor L1, diode D4, and control switch Q16. In the embodiment shown in FIG. 4, the control switch Q16 is mounted outside the dimming controller 308. In another embodiment, the control switch Q16 can be built into the dimming controller 308.

The dimming controller 308 receives a switch monitoring signal indicating the operation of a power switch such as the power switch 304 that is coupled between the power source and the light source driving circuit, and is coupled in series with the LED string 312 according to the switch monitoring signal. By controlling switch Q16, it can operate to adjust the regulated power from power converter 310 (including inductor L1, diode D4, and control switch Q16). The light source driving circuit 400 may further include an AC / DC converter 306 that converts the AC input voltage V _IN into a DC output voltage V _OUT and a current sensor 314 that detects the LED current passing through the LED string 312. In the example of FIG. 4, the AC / DC converter 306 may be a bridge rectifier including diodes D1, D2, D7, D8, D10, and a capacitor C9. The current sensor 314 can include a current sensing resistor R5.

  In one embodiment, the terminals of dimming controller 308 may include HV_GATE, SEL, CLK, RT, VDD, CTRL, MON, and GND. Terminal HV_GATE is coupled to switch Q27 through resistor R3 in order to control the conductive state, such as the connection / disconnection state of switch Q27 coupled to LED string 312. Capacitor C11 is coupled between terminal HV_GATE and ground to adjust the gate voltage of switch Q27.

  The user can dimm, such as analog dimming mode or burst dimming mode, by coupling terminal SEL to ground through resistor R4 (as shown in Figure 4) or by directly coupling terminal SEL to ground. A mode can be selected.

  Terminal CLK is coupled to AC / DC converter 306 through resistor R3 and to ground through resistor R6. The terminal CLK can receive a switch monitoring signal indicating the operation of the power switch 304. In one embodiment, the switch monitoring signal can be generated at a common node between resistors R3 and R6. Capacitor C12 is coupled in parallel with resistor R6 to filter unwanted noise. Terminal RT is coupled to ground through resistor R7 to determine the frequency of the pulse signal generated by dimming controller 308.

  Terminal VDD is coupled to switch Q27 through diode D9 to supply power to dimming controller 308. In one embodiment, an energy storage unit such as capacitor C10 coupled between terminal VDD and ground can supply power to dimming controller 308 when power switch 304 is turned off. In an alternative embodiment, the energy storage unit can be integrated into the dimming controller 308. Terminal GND is coupled to ground.

  Terminal CTRL is coupled to control switch Q16. Control switch Q16 is coupled in series with LED string 312 and switch Q27 and is coupled to ground through current sensing resistor R5. The dimming controller 308 adjusts the adjusted power from the power converter 310 by using the control signal via the terminal CTRL and controlling the conductive state such as the on and off states of the control switch Q16. Can work. Terminal MON couples to current sensing resistor R5 to receive a current monitoring signal indicative of the LED current passing through LED string 312. When the switch Q27 is connected, the dimming controller 308 can adjust the LED current passing through the LED string 312 to the ground by controlling the control switch Q16.

  During operation, when the power switch 304 is turned on, the AC / DC converter 306 converts the input AC voltage Vin to the DC voltage Vout. A predetermined voltage at the terminal HV_GATE is supplied to the switch Q27 through the resistor R3, so that the switch Q27 is connected.

  When the dimming controller 308 connects the control switch Q16, the DC voltage Vout supplies power to the LED string 312 and charges the inductor L1. The LED current passes through the inductor L1, the LED string 312, the switch Q27, the control switch Q16, and the current detection resistor R5 to reach the ground. When the dimming controller 308 turns off the control switch Q16, the LED current passes through the inductor L1, the LED string 312, and the diode D4. The inductor L1 is discharged so as to supply power to the LED string 312. Therefore, the dimming controller 308 can adjust the adjusted power from the power converter 310 by controlling the control 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 a switch monitoring signal indicating the power shutoff operation of power switch 304 can be detected by dimming controller 308 through terminal CLK. Similarly, when connecting the power switch 304, the voltage across the resistor R6 rises to a predetermined voltage, and therefore the switch monitoring signal indicating the power-on operation of the power switch 304 is dimmed through the terminal CLK. It can be detected by the device 308. When a power shutdown operation is detected, the dimming controller 308 can turn off the switch Q27 by pulling the voltage at the terminal HV_GATE to zero, and after the inductor L1 completes the discharge, the LED string 312 The power supply can be cut off. In response to the power shutdown operation, the dimming controller 308 can adjust the reference signal indicating the target light output of the LED string 312. Therefore, when the power switch 304 is turned on next time, the LED string 312 can generate a light output according to the adjusted target light output. In other words, the light output of the LED array 312 can be adjusted by the dimming controller 308 in response to the power cut-off operation of the power switch 304.

  FIG. 5 shows an example of the configuration of the dimming controller 308 of FIG. 4 according to one embodiment of the present invention. FIG. 5 is described in combination with FIG. Elements having the same reference numerals as in FIG. 4 have similar functions and will not be described in detail here.

  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 coupled to ground through a Zener diode ZD1. The trigger monitoring unit 506 can receive a switch monitoring signal indicating the operation of the external power switch 304 through the terminal CLK, and generates a drive signal for driving the counter 526 when the operation of the external power switch 304 is detected at the terminal CLK. Can be made. The trigger monitoring unit 506 can be further operated to control the conductive state of the switch Q27. The dimmer 502 generates the reference signal REF and adjusts the power of the LED string 312 in the analog dimming mode, or generates the control signal 538 and adjusts the duty cycle of the PWM signal PWM1 to adjust the LED string 312 Can operate to regulate the power of the. The pulse signal generator 504 is operable to generate a pulse signal that can be brought into contact with the control switch Q16. Dimming controller 308 is a start-up and undervoltage lockout (UVL) circuit that couples to terminal VDD to selectively power one or more elements of dimming controller 308 in response to different power conditions 508 may further be included.

  In one embodiment, the start and undervoltage lockout circuit 508 is operable to power on all elements of the dimming controller 308 when the voltage at the terminal VDD is greater than the first predetermined voltage. it can. When turning off the power switch 304, the start-up and undervoltage lockout circuit 508 causes the trigger monitoring unit 506 and dimmer to conserve energy if the voltage at terminal VDD is less than the second predetermined voltage. Except for 502, other elements of the dimming controller 308 can be operated to power off. The start and undervoltage lockout circuit 508 can further operate to power off the trigger monitoring unit 506 and the dimmer 502 when the voltage at the terminal VDD is less than the third predetermined voltage. In one embodiment, the first predetermined voltage is greater than the second predetermined voltage, and the second predetermined voltage is greater than the third predetermined voltage. The dimming controller 308 can be powered by the capacitor C10 through the terminal VDD, so that the trigger monitoring unit 506 and the dimmer 502 still operate for a predetermined time after the power switch 304 is turned off. can do.

  In dimming controller 308, terminal SEL is coupled to current source 532. The user can select the dimming mode by setting the terminal SEL, for example, by directly coupling the terminal SEL to ground or by coupling the terminal SEL to ground through a resistor. In one embodiment, the dimming mode can be determined by measuring the voltage at terminal SEL. When terminal SEL is directly coupled to ground, the voltage at terminal SEL is approximately equal to zero. The control circuit can then turn on switch 540, turn off switch 541, and turn off switch 542. Thus, the dimming controller 308 can operate in an analog dimming mode and can adjust the power of the LED string 312 (shown in FIG. 4) by adjusting the reference signal REF. In one embodiment, when the terminal SEL is coupled to ground through a resistor R4 (shown in FIG. 4) having a predetermined resistance value, the voltage at the terminal SEL can be greater than zero. The control circuit can then disconnect switch 540, switch 541 in contact, and switch 542 in contact. Therefore, the dimming controller 308 can operate in the burst dimming mode, and can adjust the power of the LED string 312 (shown in FIG. 4) by adjusting the duty cycle of the PWM signal PWM1. In other words, different dimming modes can be selected by controlling the connection / disconnection state of the switch 540, the switch 541, and the switch 542. The connection / disconnection state of the switch 540, the switch 541, and the switch 542 can be determined by the voltage at the terminal SEL.

  Pulse signal generator 504 couples to ground through terminal RT and resistor R7 to generate a pulse signal 536 that can be connected to control switch Q16. The pulse signal generator 504 can have different configurations, and is not limited to the configuration shown in the example of FIG.

  In the pulse signal generator 504, the non-inverting input of the operational amplifier 510 receives a predetermined voltage V1. Therefore, the voltage at the inverting input of the operational amplifier 510 can be V1. Current IRT passes through terminal RT and resistor R7 to ground. Current I1 passing through MOSFET 514 and MOSFET 515 is equal to IRT. Since MOSFET 514 and MOSFET 512 constitute a current mirror, the current I2 passing through MOSFET 512 is also approximately equal to IRT. The output of comparator 516 and the output of comparator 518 are coupled to the S and R inputs of SR flip-flop 520, respectively. The inverting input of the comparator 516 receives a predetermined voltage V2. The non-inverting input of the comparator 518 receives a predetermined voltage V3. In one embodiment, V2 is greater than V3 and V3 is greater than zero. Capacitor C4 is coupled between MOSFET 512 and ground and has one side coupled to a common node between the non-inverting input of comparator 516 and the inverting input of comparator 518. The Q output of SR flip-flop 520 is coupled to switch Q15 and the S input of SR flip-flop 522. Switch Q15 is coupled in parallel with capacitor C4. The conductive state such as the connection / disconnection state of the switch Q15 can be determined by the Q output of the SR flip-flop 520.

  Initially, the voltage across capacitor C4 is approximately equal to zero, which is less than V3. Thus, the R input of SR flip-flop 520 receives a digital 1 from the output of comparator 518. The Q output of SR flip-flop 520 is set to digital 0, which turns off switch Q15. When the switch Q15 is turned off, the capacitor C4 is charged by I2, so the voltage across the capacitor C4 increases. When the voltage across C4 is greater than V2, the S input of SR flip-flop 520 receives a digital 1 from the output of comparator 516. The Q output of SR flip-flop 520 is set to digital 1, which connects switch Q15. When switch Q15 is connected, capacitor C4 discharges through switch Q15, so the voltage across C4 decreases. When the voltage across capacitor C4 drops below V3, comparator 518 outputs a digital 1, and the Q output of SR flip-flop 520 is set to digital 0, which turns off switch Q15. Next, the capacitor C4 is charged again by I2. Thus, through the process described above, the pulse signal generator 504 can generate a pulse signal 536 that includes a series of pulses at the Q output of the SR flip-flop 520. Pulse signal 536 is sent to the S input of SR flip-flop 522.

  The trigger monitoring unit 506 is operable to monitor the operation of the power switch 304 through the terminal CLK, and generates a drive signal that drives the counter 526 when the operation of the power switch 304 is detected at the terminal CLK. Can work. In one embodiment, when power switch 304 is connected, the voltage at terminal CLK rises to a level equal to the voltage across resistor R6 (shown in FIG. 4). When the power switch 304 is turned off, the voltage at the terminal CLK drops to zero. Therefore, a switch monitoring signal indicating the operation of the power switch 304 can be detected at the terminal CLK. In one embodiment, the trigger monitoring unit 506 generates a drive signal when a power shutdown operation is detected at the terminal CLK.

  The trigger monitoring unit 506 can be further operated to control the conductive state of the switch Q27 through the terminal HV_GATE. When the power switch 304 is connected, the breakdown voltage across the Zener diode ZD1 is applied to the switch Q27 through the resistor R3. Therefore, the switch Q27 can be brought into contact. The trigger monitoring unit 506 can turn off the switch Q27 by pulling the voltage at the terminal HV_GATE to zero. In one embodiment, the trigger monitoring unit 506 disconnects the switch Q27 when a power cut-off operation of the power switch 304 is detected at the terminal CLK, and switches off when the power-on operation of the power switch 304 is detected at the terminal CLK. Contact Q27.

  In one embodiment, the dimmer 502 includes a counter 526 coupled to the trigger monitoring unit 506 that counts the operation of the power switch 304 and a digital-to-analog converter (D / A converter) 528 coupled to the counter 526. Including. The dimmer 502 can further include a PWM generator 530 coupled to the D / A converter 528. The counter 526 can be driven by a drive signal generated by the trigger monitoring unit 506. More specifically, in one embodiment, when the power switch 304 is turned off, the trigger monitoring unit 506 detects a negative edge of the voltage at the terminal CLK and generates a drive signal. The count value of the counter 526 can be increased by, for example, 1 in response to the drive signal. The D / A converter 528 reads the count value from the counter 526 and generates a dimming signal (for example, the control signal 538 or the reference signal REF) based on the count value. The dimming signal can be used to adjust the target power level of the power converter 310 and then the light output of the LED string 312 can be adjusted.

  In the burst dimming mode, the switch 540 is turned off, and the switch 541 and the switch 542 are connected. The inverting input of the comparator 534 receives a reference signal REF1, which can be a DC signal having a predetermined substantially constant voltage. The voltage REF1 can determine the peak value of the LED current, which in turn can determine the maximum light output of the LED string 312. The dimming signal can be a control signal 538 applied to the PWM generator 530 to adjust the duty cycle of the PWM signal PWM1. By adjusting the duty cycle of PWM1, the light output of LED string 312 can be adjusted to the same magnitude as the maximum light output determined by REF1. For example, when PWM1 has a 100% duty cycle, the LED string 312 can have a maximum light output. When the duty cycle of PWM1 is less than 100%, the LED string 312 can have a light output that is lower than the maximum light output.

  In the analog dimming mode, the switch 540 is connected, the switch 541 and the switch 542 are disconnected, and the dimming signal can be an analog reference signal REF having an adjustable voltage. The D / A converter 528 can adjust the voltage of the reference signal REF according to the count value of the counter 526. The voltage at REF can determine the peak value of the LED current, and then the average value of the LED current. Therefore, the light output of the LED string 312 can be adjusted by adjusting the reference signal REF.

  In one embodiment, the D / A converter 528 can decrease the voltage at REF in response to an increase in the count value. For example, when the count value is 0, the D / A converter 528 adjusts the reference signal REF to have the voltage V4. When the power-off operation of the power switch 304 is detected at the terminal CLK by the trigger monitoring unit 506, if the count value increases to 1, the D / A converter 528 has the reference signal REF so that it has a voltage V5 less than V4. Adjust. In yet another embodiment, the D / A converter 528 can increase the voltage at REF in response to an increase in the count value.

  In one embodiment, after the counter 526 reaches its maximum count value, the count value is reset to zero. For example, when the counter 526 is a 2-bit counter, the count value increases from 0 to 1, 2, and 3, and then returns to zero after four power-off operations are detected. Thus, the light output of the LED string 312 can be adjusted from the first level to the second level, then to the third level, then to the fourth level, and then back to the first level.

  The inverting input of the comparator 534 can selectively receive the reference signal REF and the reference signal REF1. For example, the inverting input of the comparator 534 receives the reference signal REF through the switch 540 in the analog dimming mode and the reference signal REF1 through the switch 541 in the burst dimming mode. The non-inverting input of comparator 534 is coupled to resistor R5 through terminal MON to receive current monitoring signal SEN from current sensing resistor R5. The voltage of the current monitoring signal SEN can indicate the LED current passing through the LED string 312 when the switch Q27 and the control switch Q16 are connected.

  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. A PWM signal PWM1 generated by the PWM generator 530 is applied to the AND gate 524. The AND gate 524 outputs a control signal and controls the control switch Q16 through the terminal CTRL.

  When the analog dimming mode is selected, the switch 540 is turned on and the switches 541 and 542 are turned off. The control switch Q16 is controlled by the SR flip-flop 522. During operation, when the power switch 304 is in contact, the breakdown voltage across the Zener diode ZD1 causes the switch Q27 to be in contact. In response to the pulse signal 536 generated by the pulse generator 504, the SR flip-flop 522 generates a digital 1 at the Q output and connects the control switch Q16. The LED current passes through the inductor L1, the LED string 312, the switch Q27, the control switch Q16, and the current detection resistor R5 to reach the ground. As the inductor resists sudden changes in the LED current, the LED current increases gradually. As a result, the voltage across the current sensing resistor R5, that is, the voltage of the current monitoring signal SEN can be increased. When the voltage on SEN is greater than the voltage on the reference signal REF, the comparator 534 generates a digital 1 at the R input of the SR flip-flop 522, which results in the SR flip-flop 522 generating a digital 0 and the control switch Turn off Q16. After turning off the control switch Q16, the inductor L1 discharges and supplies power to the LED string 312. The LED current passing through the inductor L1, the LED string 312 and the diode D4 gradually decreases. When SR flip-flop 522 receives a pulse again at the S input, control switch Q16 is turned on, at which time the LED current again passes through current sensing resistor R5 to ground. When the voltage of the current monitoring signal SEN is larger than the voltage of the reference signal REF, the control switch Q16 is turned off by the SR flip-flop 522. As described above, the reference signal REF can determine the peak value of the LED current and then the light output of the LED string 312. The light output of the LED array 312 can be adjusted by adjusting the reference signal REF.

  In the analog dimming mode, when the power switch 304 is turned off, the capacitor C10 (shown in FIG. 4) discharges and supplies power to the dimming controller 308. When the trigger monitoring unit 506 detects the power-off operation of the power switch 304 at the terminal CLK, the count value of the counter 526 can be increased by one. The trigger monitoring unit 506 can turn off the switch Q27 in response to the power-off operation of the power switch 304. The D / A converter 528 can adjust the voltage of the reference signal REF from the first level to the second level in response to the change in the count value. Therefore, when the power switch 304 is connected, the light output of the LED row 312 can be adjusted according to the adjusted reference signal REF.

  When the burst dimming mode is selected, the switch 540 is turned off and the switches 541 and 542 are connected. The inverting input of the comparator 534 receives a reference signal REF1 having a predetermined voltage. Control switch Q16 is controlled by both SR flip-flop 522 and PWM signal PWM1 through AND gate 524. The reference signal REF1 can determine the peak value of the LED current, and then determine the maximum light output of the LED string 312. The duty cycle of the PWM signal PWM1 can determine the connection / disconnection time of the control switch Q16. When the PWM signal PWM1 is logic 1, the conductive state of the control switch Q16 is determined by the Q output of the SR flip-flop 522. When the PWM signal PWM1 is logic 0, the control switch Q16 is turned off. By adjusting the duty cycle of the PWM signal PWM1, the power of the LED string 312 can be adjusted accordingly. Therefore, the combination of the reference signal REF1 and the PWM signal PWM1 can determine the light output of the LED array 312.

  In the burst dimming mode, when the power switch 304 is turned off, the power cut-off operation of the power switch 304 can be detected by the trigger monitoring unit 506 at the terminal CLK. The trigger monitoring unit 506 turns off the switch Q27 and generates a drive signal. The count value of the counter 526 can be increased by, for example, 1 in response to the drive signal. The D / A converter 528 can generate the control signal 538 to adjust the duty cycle of the PWM signal PWM1 from the first level to the second level. Therefore, when the power switch 304 is turned on next time, the light output of the LED row 312 can be adjusted to follow the target light output determined by the reference signal REF1 and the PWM signal PWM1.

  FIG. 6 shows the signal waveform of the LED current 602 passing through the LED string 312, the signal waveform of the pulse signal 536, the signal waveform of V522 indicating the output of the SR flip-flop 522, and the output of the AND gate 524 in the analog dimming mode. An example of the signal waveform of V524 and the connection / disconnection state of the control switch Q16 is shown. FIG. 6 is described in combination with FIG. 4 and FIG.

  During operation, the pulse signal generator 504 generates a pulse signal 536. SR flip-flop 522 generates a digital 1 at the Q output in response to each pulse of pulse signal 536. When the Q output of the SR flip-flop 522 is digital 1, the control switch Q16 is connected. When the control switch Q16 is connected, the inductor L1 is ramped up and the LED current 602 is increased. When the LED current 602 reaches the peak value Imax, it means that the voltage of the current monitoring signal SEN is approximately equal to the voltage of the reference signal REF, and the comparator 534 generates a digital 1 at the R input of the SR flip-flop 522 As a result, the SR flip-flop 522 generates a digital 0 at the Q output. When the Q output of the SR flip-flop 522 is digital 0, the control switch Q16 is turned off. When the control switch Q16 is turned off, the inductor L1 is discharged to supply power to the LED string 312 and the LED current 602 decreases. In this analog dimming mode, by adjusting the reference signal REF, the average LED current can be adjusted accordingly, and thus the light output of the LED string 312 can be adjusted.

  FIG. 7 shows the signal waveform of the LED current 602 passing through the LED string 312, the signal waveform of the pulse signal 536, the signal waveform of V522 indicating the output of the SR flip-flop 522, and the output of the AND gate 524 in the burst dimming mode. An example of the signal waveform of V524, the connection / disconnection state of the control switch Q16, and the signal waveform of the PWM signal PWM1 is shown. FIG. 7 is described in combination with FIG. 4 and FIG.

  When PWM1 is digital 1, the relationship among the LED current 602, the pulse signals 536, V522, V524, and the connection / disconnection state of the switch Q1 is the same as the relationship shown in FIG. When PWM1 is digital 0, the output of AND gate 524 changes to digital 0. Therefore, the control switch Q16 is turned off and the LED current 602 decreases. When PWM1 holds digital 0 long enough, the LED current 602 can drop to zero. In the burst dimming mode, by adjusting the PWM1 duty cycle, the average LED current can be adjusted accordingly, and thus the light output of the LED string 312 can be adjusted.

  FIG. 8 shows an example of a diagram illustrating the operation of a light source drive circuit including the dimming controller of FIG. FIG. 8 is described in combination with FIG.

  In the example shown in FIG. 8, the count value of the counter 526 increases by 1 every time the power monitoring operation of the power switch 304 is detected by the trigger monitoring unit 506. The counter 526 may be a 2-bit counter having a maximum count value of 3.

  In the analog dimming mode, the D / A converter 528 reads the count value from the counter 526 and decreases the voltage of the reference signal REF in response to the increase in the count value. The voltage at REF can determine the peak value Imax of the LED current, and then the average value of the LED current can be determined. In the burst dimming mode, the D / A converter 528 reads the count value from the counter 526 and decreases the duty cycle of the PWM signal PWM1 in response to the increase in the count value (for example, decreases by 25% each time). The counter 526 is reset after reaching its maximum count value (eg, 3).

  FIG. 9 shows a flowchart 900 of a method for adjusting the output of a light source, according to one embodiment of the invention. FIG. 9 is described in combination with FIG. 4 and FIG.

  In block 902, a light source such as LED string 312 is powered with regulated power from a power converter such as power converter 310. In block 904, a switch monitoring signal may be received, for example, by the dimming controller 308. The switch monitoring signal can indicate the operation of a power switch such as power switch 304 that couples between the power source and the power converter. At block 906, a dimming signal is generated in response to the switch monitoring signal. At block 908, a switch coupled in series with the light source, such as control switch Q16, is controlled in response to the dimming signal to adjust the adjusted power from the power converter. In one embodiment, in the analog dimming mode, the adjusted power from the power converter can be adjusted by comparing the dimming signal with a feedback current monitoring signal indicative of the light source current from the light source. In another embodiment, in burst dimming mode, the adjusted power from the power converter can be adjusted by controlling the duty cycle of the PWM signal with the dimming signal.

  Therefore, the embodiment according to the present invention provides a light source driving circuit capable of adjusting the power of a light source according to a switch monitoring signal indicating the operation of a power switch such as a connection / disconnection switch attached to a wall. The power of the light source supplied by the power converter can be adjusted by the dimming controller by controlling a switch coupled in series with the light source. Advantageously, as described above, the user can adjust the light output of the light source through a common connection / disconnection power switch operation (eg, a power-off operation). Therefore, an additional device for dimming such as an external dimmer or a specially designed switch with an adjustment button can be avoided, and the cost can be reduced.

  FIG. 10 shows an example of a schematic diagram of a light source driving circuit 1000 according to an embodiment of the present invention. FIG. 10 is described in combination with FIG. Elements having the same reference numerals as in FIGS. 3 and 4 have similar functions.

  The light source drive circuit 1000 includes a power converter 310 coupled to the power supply and the LED string 312 that receives power from the power supply and provides regulated power to the LED string 312. The dimming controller 1008 can operate to monitor the power switch 304 coupled between the power source and the light source driving circuit 1000 by monitoring the voltage at the terminal CLK. The dimming controller 1008 is operable to receive a dimming request signal indicating the operation of the first set of power switches 304 and to receive a dimming end signal indicating the operation of the second set of power switches 304. it can. The dimming controller 1008 can receive the dimming request signal and the dimming end signal via the terminal CLK. The dimming controller 1008 continuously adjusts the adjusted power from the power converter 310 when receiving the dimming request signal and adjusts the adjusted power from the power converter 310 when receiving the dimming end signal. Can be further operated to abort. In other words, when the dimming controller 1008 detects the operation of the first set of the power switch 304, it continuously supplies the power from the power converter 310 until it detects the operation of the second set of the power switch 304. Can be adjusted. In one embodiment, the dimming controller 1008 can adjust the regulated power from the power converter 310 by controlling a control switch Q16 coupled in series with the LED string 312.

  FIG. 11 shows an example of the configuration of the dimming controller 1008 of FIG. 10, according to one embodiment of the present invention. FIG. 11 is described in combination with FIG. Elements having the same reference numerals as those in FIGS. 4, 5, and 10 have the same functions.

  In the example of FIG. 11, the configuration of the dimming controller 1008 in FIG. 11 is the same as the configuration of the dimming controller 308 in FIG. 5 except for the configurations of 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 end signal via the terminal CLK, and operates to generate the signal EN to enable or disable the clock generator 1104. it can. The trigger monitoring unit 1106 can further operate to control the conductive state of the switch Q27 coupled to the LED string 312.

  The dimmer 1102 generates the reference signal REF to adjust the power of the LED string 312 in the analog dimming mode, or the PWM signal PWM1 to adjust the power of the LED string 312 in the burst dimming mode. Can be operated to generate a control signal 538 that adjusts the duty cycle. In the example shown in FIG. 11, the dimmer 1102 generates a clock signal, a clock generator 1104 coupled to the trigger monitoring unit 1106, a counter 1126 driven by the clock signal, and a digital analog coupled to the counter 1126 ( D / A) converter 528. The dimmer 1102 can further include a PWM generator 530 coupled to the D / A converter 528.

  In operation, when the power switch 304 is turned on or off, the trigger monitoring unit 1106 can detect the positive or negative edge of the voltage at the terminal CLK. For example, when the power switch 304 is turned off, the capacitor C10 is discharged and supplies power to the dimming controller 1008. The voltage across resistor R6 drops to zero. Therefore, the negative edge of the voltage at the terminal CLK can be detected by the trigger monitoring unit 1106. Similarly, when the power switch 304 is connected, the voltage across the resistor R6 rises to a predetermined voltage. Therefore, the positive edge of the voltage at the terminal CLK can be detected by the trigger monitoring unit 1106. Therefore, an operation such as a power-on operation or a power-off operation of the power switch 304 can be detected by monitoring the voltage at the terminal CLK by the trigger monitoring unit 1106.

  In one embodiment, the dimming request signal can be received via the terminal CLK by the trigger monitoring unit 1106 when detecting a first set of operations of the power switch 304. The dimming end signal can be received by the trigger monitoring unit 1106 via the terminal CLK when detecting the second set of operations of the power switch 304. In one embodiment, the first set of operations of the power switch 304 includes a first power-up operation following the first power-off operation. In one embodiment, the second set of operations of the power switch 304 includes a second power-up operation following the second power-off operation.

  When the trigger monitoring unit 1106 receives the dimming request signal, the dimming controller 1008 begins to continuously adjust the adjusted power from the power converter 310. In the analog dimming mode, the dimming controller 1008 adjusts the voltage of the reference signal REF and adjusts the adjusted power from the power converter 310. In the burst dimming mode, the dimming controller 1008 adjusts the duty cycle of the PWM signal PWM1 to adjust the adjusted power from the power converter 310.

  When the trigger monitoring unit 1106 receives the dimming end signal, the dimming controller 1008 can stop adjusting the adjusted power from the power converter 310.

  FIG. 12 shows an example of a diagram illustrating the operation of the light source drive circuit including the dimming controller 1008 of FIG. 11, according to one embodiment of the present invention. FIG. 12 is described in combination with FIG. 10 and FIG.

  First, assume that power switch 304 is off. In one embodiment, during operation, for example, when the user turns on the power switch 304, the LED string 312 is powered by the regulated power from the power converter 310 to generate the initial light output. In the analog dimming mode, the initial light output can be determined by the initial voltage of the reference signal REF. In the burst dimming mode, the first light output can be determined by the first duty cycle (eg, 100%) of the PWM signal PWM1. In one embodiment, the reference signal REF and the PWM signal PWM1 can be generated by the D / A converter 528 in accordance with the count value of the counter 1126. Thus, the first voltage at REF and the first duty cycle of PWM1 can be determined by the first count value provided by counter 1126 (eg, 0).

  To adjust the light output of the LED string 312, the user can perform a first set of operations on the power switch 304. When the operation of the first set of power switches 304 is detected, a dimming request signal is generated. In one embodiment, the first set of operations can include a first power-up operation following the first power-off operation. As a result, the trigger monitoring unit 1106 can detect and receive a dimming request signal including the positive edge 1206 following the negative edge 1204 of the voltage at the terminal CLK. In response to the dimming request signal, the trigger monitoring unit 1106 can generate a high level signal EN. Therefore, the clock generator 1104 generates a clock signal. The counter 1126 driven by the clock signal can change the count value in response to each clock pulse of the clock signal. In the example of FIG. 12, the count value increases in response to the clock signal. In one embodiment, after the counter 1126 reaches its predetermined maximum count value, the count value can be reset to zero. In another embodiment, the count value increases until the counter 1126 reaches its predetermined maximum count value and decreases until the counter 1126 reaches its predetermined minimum count value.

  In one embodiment, in the analog dimming mode, the D / A converter 528 reads the count value from the counter 1126 and decreases the voltage of the reference signal REF in response to the increase in the count value. In one embodiment, in burst dimming mode, the D / A converter 528 reads the count value from the counter 1126 and decreases the duty cycle of the PWM signal PWM1 in response to the increase in count value (e.g., decreases by 10% each time). ) Therefore, the adjusted power from the power converter 310 can be determined by the voltage of the reference signal REF (in analog dimming mode) or the duty cycle of the PWM signal PWM1 (in burst dimming mode), so the LED string 312 light output can be adjusted.

  When the desired light output is reached, the user can end the adjustment process by performing a second set of actions on the power switch 304. When the operation of the second set of the power switch 304 is detected, a dimming end signal is generated. In one embodiment, the second set of operations can include a second power-up operation following the second power-off operation. As a result, the trigger monitoring unit 1106 can detect and receive a dimming end signal including the positive edge 1210 following the negative edge 1208 of the voltage at the terminal CLK. Upon detecting the dimming end signal, the trigger monitoring unit 1106 can generate a low level signal EN. Therefore, the clock generator 1104 is disabled so that the counter 1126 can hold the count value. Therefore, in the analog dimming mode, the voltage of the reference signal REF can be held at a desired level. In the burst dimming mode, the duty cycle of the PWM signal PWM1 can be held at a desired value. Therefore, the light output of the LED array 312 can be maintained at a desired light output.

  FIG. 13 shows a flowchart 1300 of a method for adjusting the power of a light source, according to one embodiment of the invention. FIG. 13 is described in combination with FIG. 10 and FIG.

  In block 1302, a light source such as LED string 312 is powered with regulated power from a power converter such as power converter 310.

  In block 1304, the dimming request signal may be received by the dimming controller 1008, for example. The dimming request signal can indicate the operation of a first set of power switches, such as power switch 304, coupled between the power source and the power converter. In one embodiment, the first set of power switch operations includes a first power-up operation following the first power-off operation.

  In block 1306, the adjusted power from the power converter is continuously adjusted, eg, by the dimming controller 1008. In one embodiment, the clock generator 1104 can drive the counter 1126. In accordance with the count value of the counter 1126, a dimming signal (for example, the control signal 538 or the reference signal REF) can be generated. In the analog dimming mode, the adjusted power from the power converter can be adjusted by comparing the reference signal REF and a feedback current monitoring signal indicating the light source current of the light source. The voltage of REF can be determined by the count value. In the burst dimming mode, the adjusted power from the power converter can be adjusted by changing the duty cycle of the PWM signal PWM1 by the control signal 538. The duty cycle of PWM1 can also be determined by the count value.

  In block 1308, the dimming end signal may be received by the dimming controller 1008, for example. The dimming end signal can indicate the operation of a second set of power switches, such as power switch 304, coupled between the power source and the power converter. In one embodiment, the second set of power switch operations includes a second power-up operation following the second power-off operation.

  At block 1310, adjustment of the adjusted power from the power converter ends when a dimming end signal is received. In one embodiment, the clock generator 1104 is disabled, allowing the counter 1126 to hold its count value. As a result, in the analog dimming mode, the voltage of REF can be held at a desired level. In the burst dimming mode, the duty cycle of the PWM signal PWM1 can be held at a desired value. As a result, the light source can maintain a desired light output.

  Therefore, the embodiment according to the present invention provides a light source driving circuit capable of automatically and continuously adjusting the power of the light source when receiving the dimming request signal. When the light source driving circuit receives the dimming end signal, the light source driving circuit can stop adjusting the power of the light source. Advantageously, the user can adjust the light intensity / luminance by performing a first set of operations on a power switch, such as a connect / disconnect switch mounted on the wall. During the light intensity adjustment process, the light output of the light source gradually decreases or increases. When the desired light output is reached, the user can end the light intensity adjustment by performing a second set of actions on the power switch. Therefore, an additional device for dimming such as an external dimmer or a specially designed switch with an adjustment button can be avoided, and the cost can be reduced.

  FIG. 14A shows a schematic diagram of an example LED light source drive system 1400, according to one embodiment of the invention. FIG. 14A is described in combination with FIG. Elements having the same reference numerals as in FIG. 10 have similar functions.

In one embodiment, the drive system 1400 receives AC power through the power switch 304 and generates regulated power to the LED light source. The power switch 304 may be a connection / disconnection switch that is attached to the wall. An example of the power switch 304 is shown in FIG. 14B. By switching the element 1480 to the contact position or the disconnection position, the conductive state of the power switch 1404 is controlled to be contact or disconnection by the user, for example. In the example of FIG. 14A, drive system 1400 includes a power conversion circuit such as AC / DC converter 306 and DC / DC converter 1410, and a dimming control circuit such as dimming controller 1408. The power conversion circuit receives an AC signal such as the AC input voltage V _IN supplied by the AC power supply through the power switch 304 and supplies adjusted power such as the adjusted current I _REG to the LED light source 1412. In the example of FIG. 14A, the LED light source 1412 includes an LED string. More specifically, the AC / DC converter 306 of the conversion circuit receives AC power (eg, AC input voltage V _IN ) and converts the AC power into DC power (eg, DC output voltage V _OUT ). The DC / DC converter 1410 of the conversion circuit, for example, by controlling a control switch Q16 coupled in series to the LED light source via the DC / DC converter 1410 in response to a dimming signal (not shown in FIG. 14A). , DC power (eg, DC output voltage V _OUT ) is converted to adjusted power (eg, adjusted power I _REG ). The dimming controller 1408 generates a dimming signal and controls dimming of the LED light source 1412 according to the dimming signal. The dimming controller 1408 generates a dimming signal in response to a set of operations of the power switch 304, such as a sinusoidal full-wave or sinusoidal half-wave, or AC The dimming signal is adjusted by counting the periodic cycles of the signal _VIN . For illustrative purposes, the AC signal V _IN is a sine signal. However, the present invention is not limited to sinusoidal AC signals.

As an example, the full bridge circuit of AC / DC converter 306, including, for example, diodes D1, D2, D7, and D8, receives an AC input voltage V _IN from an AC power source, and is a sine with a polarity, for example, to filter capacitor C9. Generate a half wave. Therefore, the filter capacitor C9 can supply the DC output voltage V _OUT to the DC / DC converter 1410. A resistor divider including resistors R3 and R6 can provide a dimming request signal or dimming end signal indicating a set of operations of power switch 304. Similar to the operation of the power switch 304 described in FIG. 10, the operation of the power switch 304 in FIG. 14A is performed by connecting the power switch 304 that continues within a predetermined time interval ΔT such as 2 seconds from the step of disconnecting the power switch 304. Including the steps of: In response to the dimming request signal, the dimming controller 1408 can enable the dimming process of the LED light source 1412. In response to the dimming end signal, the dimming controller 1408 ends the dimming process. In addition, when the power switch 304 is connected, the resistor divider supplies a periodic signal 1454 indicating a sine half wave of the AC signal V _IN to the dimming controller 1408.

In the example of FIG. 14A, power converter 1410 is a buck converter that includes control switch Q16, diode 1414, current sensor 1428 (eg, a resistor) coupled to inductors L1 and L2, and capacitor 1424. In one embodiment, the control switch Q16 can be incorporated in the dimming controller 1408. Inductors L1 and L2 are both magnetically and electrically coupled to, for example, common node 1433. The common node 1433 in FIG. 14A is between the resistor 1428 and the inductor L1, but in another embodiment, the common node 1433 can be located between the control switch Q16 and the resistor 1428. The common node 1433 provides a reference ground to the dimming controller 1408. In one embodiment, the reference ground of dimming controller 1408 is different from the ground of drive system 1400. By connecting and disconnecting the control switch Q16, the adjusted current I _REG passing through the inductor L1 can be adjusted, thereby adjusting the power supplied to the LED light source 1412. Capacitor 1424 absorbs ripple of adjusted current I _{REG so} that the current passing through LED light source 1412 is smooth and approximately equal to the average of adjusted current I _REG . In addition, the inductor L2 detects whether the electrical state of the inductor L1, eg, the current passing through the inductor L1, is reduced to a predetermined minimum level. The inductor L2 further generates a detection signal AUX indicating the electrical state of the inductor L1. Resistor 1428 has one end coupled to the node between switch Q16 and the cathode of diode 1414, and the other end coupled to the reference ground. Resistor 1428 provides a current monitoring signal SEN indicative of adjusted current I _REG passing through inductor L1.

In the example of FIG. 14A, the dimming controller 1408 has terminals CLK, ZCD, GND, CTRL, VDD, MON, COMP, and FB. Terminal ZCD is coupled to inductor L2 and receives detection signal AUX. Terminal MON is coupled to resistor 1428 and receives monitoring signal SEN. The terminal COMP is coupled to the reference ground of the dimming controller 1408 through a capacitor and supplies the compensation voltage REF2 to the dimming controller 1408. The terminal FB receives a monitoring signal AVG indicating the average of the current I _REG passing through the inductor L1. The terminal CLK monitors whether the power switch 304, for example, the power switch 304 is connected or disconnected. When the power switch 304 is connected, the terminal CLK in the example of FIG. 14A further receives a periodic signal 1454 indicating a sine wave of the AC signal V _IN . In another embodiment, dimming controller 1408 includes various terminals for monitoring power switch 304 and receiving periodic signal 1454, respectively. The control terminal CTRL is coupled to the control switch Q16 and generates a drive signal CTRL such as a PWM signal for controlling the control switch Q16, thereby controlling the dimming of the LED light source 1412. The drive signal CTRL is generated based on the operation of the power switch 304, and based on the periodic signal 1454, the detection signal AUX, and the monitoring signals SEN and AVG. In addition, the terminal VDD can receive power from the AC / DC converter 306 or the inductor L2. Terminal GND is coupled to the reference ground of dimming controller 1408.

More specifically, in one embodiment, the power switch 304 is in contact. In operation, when switch Q16 is connected, current I _REG passes through switch Q16, resistor 1428, inductor L1, and LED light source 1412 to the ground of drive system 1400, and current I _REG increases. When switch Q16 is turned off, current I _REG continues to pass through resistor 1428, inductor L1, LED light source 1412 and diode 1414, and current I _REG decreases. In one embodiment, the dimming controller 1408 turns off the switch Q16 and decreases the current I _REG when the monitoring signal SEN indicates that the current I _REG has increased to the maximum level I _MAX . When the detection signal AUX indicates that the current I _REG has decreased to a predetermined minimum level, the dimming controller 1408 turns on the switch Q16 and increases the current I _REG . Therefore, the current I _REG is adjusted within a range from a predetermined minimum level to a maximum level I _MAX . In one embodiment, the maximum level I _MAX is adjustable. For example, when the monitoring signal AVG indicates that the average of the current I _REG is less than the preset level, the dimming controller 1408 increases the maximum level I _MAX and increases the average of the current I _REG . When the monitoring signal AVG indicates that the average of the current I _REG is greater than the preset level, the dimming controller 1408 decreases the maximum level I _MAX and decreases the average of the current I _REG . Accordingly, the current passing through the LED light source 1412 is adjusted to a preset level. In other words, the light output of the LED light source 1412 is adjusted to a corresponding preset level.

Further, in one embodiment, a user can control the power switch 304 to control dimming of the LED light source 1412, such as controlling a preset level of light output. More specifically, the user can perform a set of operations on the power switch 304. The dimming controller 1408 generates a drive signal CTRL according to the operation of the power switch 304. As an example, when the user first turns on the power switch 304, the dimming controller 1408 generates the drive signal CTRL without depending on the dimming signal such as the reference signal REF or the PWM signal PWM1, and the LED light source 1412 Is controlled to a predetermined level such as a maximum level. Next, when the user turns off the power switch 304 and then contacts the power switch 304 within a predetermined time interval ΔT, the dimming controller 1408 generates a dimming signal and controls the driving signal CTRL. The dimming controller 1408 further adjusts the dimming signal and drive signal CTRL by counting the wave of the AC signal V _IN to control the dimming of the LED light source 1412, such as adjusting the adjusted current I _REG To do. In one embodiment, the dimming controller 1408 counts half the AC signal V _IN by counting the cycles of the periodic signal 1454. In another embodiment, the dimming controller 1408 receives AC signal V _IN directly or indirectly, can be counted half-wave or full-wave of the AC signal V _IN.

  FIG. 15 shows an example of the configuration of the dimming control circuit 1408 of FIG. 14A, according to one embodiment of the present invention. FIG. 15 is described in combination with FIG. 10 and FIG. 14A. Elements having the same reference numerals as in FIGS. 10 and 14A have the same functions. As shown in FIG. 15, the dimming control circuit 1408 includes a trigger monitoring unit 1506, a dimmer 1502, an error amplifier 1550, a comparator 534, an SR flip-flop 522, an AND gate 524, and a trigger circuit 1504. A signal generation circuit.

The trigger monitoring unit 1506 can monitor the operation of the power switch 304 via the terminal CLK and generate a pulse TRIG in response to detecting a set of operations of the power switch 304. In one embodiment, the operation includes contacting the power switch 304 that continues within a predetermined time interval ΔT from turning off the power switch 304. When such an operation occurs, the trigger monitoring unit 1506 can detect a positive edge following the negative edge of the voltage at the terminal CLK. The dimmer 1502 can count the waves of the AC signal V _IN by, for example, counting the periodic signal 1454 based on the pulse TRIG. For example, the trigger monitoring unit 1506 can generate a pulse TRIG to enable or disable the counting of the periodic signal 1454.

The dimmer 1502 includes a D / A converter 528 and a PWM generator 530, and further includes a dimming indicator 1526 and a clock generator 1504. In one embodiment, the clock generator 1504 receives the periodic signal 1454 and generates a clock signal 1544 that indicates the periodic signal 1454. For example, the clock generator 1504 can generate one pulse within each cycle of the periodic signal 1454. The dimming indicator 1526 counts the waves of the AC signal V _IN by counting the pulses of the clock signal 1544. In one embodiment, the dimming indicator 1526 further generates a digital output 1548 that indicates the dimming value in response to the counting result. As an example, when the count result exceeds a predetermined number, the dimming indicator 1526 increases the dimming value of the digital output 1548 by 1 and restarts counting. The D / A converter 528 increases the dimming signal, such as the duty cycle of the reference signal REF or PWM signal PWM1, when the digital output 1548 increases, and decreases the dimming signal when the digital output 1548 decreases. Can do. Therefore, the dimmer 1502 can adjust the dimming signal by counting the waves of the AC signal _VIN to adjust the drive signal CTRL.

Trigger circuit 1504 is coupled to terminal ZCD of dimming control circuit 1408. In one embodiment, when terminal ZCD detects that adjusted current I _REG has decreased to a predetermined minimum level, such as zero amperes, trigger circuit 1504 generates a pulse signal 1536, such as a logic high signal, and flip-flop Set Q output of 522 to logic high, and switch Q16 is connected. Further, when the current monitoring signal SEN received at the terminal MON of the dimming control circuit 1408 increases to an adjustable maximum level, such as the compensation voltage REF2, the comparator 534 outputs a logic high signal and the flip-flop 522 Reset the Q output to logic low and turn off switch Q16. Thus, the adjusted current I _REG can be adjusted within a range between a predetermined minimum level, such as zero amperes, and a maximum level determined by the compensation voltage REF2.

In the analog dimming mode, the dimming controller 1408 controls the dimming of the LED light source 1412 by comparing the reference signal REF and the monitoring signal AVG indicating the current passing through the LED light source 1412. More specifically, the error amplifier 1550 compares the reference signal REF and the monitoring signal AVG. In one embodiment, the error amplifier 1550 further increases the compensation voltage REF2 when the monitoring signal AVG is smaller than the reference signal REF, or decreases the compensation voltage REF2 when the monitoring signal AVG is larger than the reference signal REF. . Accordingly, the current through the LED light source 1412 is adjusted to a level determined by the reference signal REF. Accordingly, the light output of the LED light source 1412 is adjusted by the reference signal REF. In the burst dimming mode, the dimming controller 1408 controls dimming of the LED light source 1412 according to the PWM signal PWM1 such as the PWM signal of the flip-flop 522 and the Q output. More specifically, when the PWM signal PWM1 is a logic high, the adjusted current I _REG is adjusted by the Q output, and the average of the adjusted current I _REG is determined by the reference signal REF1. When the PWM signal PWM1 is logic low, the adjusted current I _REG is cut off. Accordingly, the light output of the LED light source 1412 can increase when the duty cycle of the PWM signal PWM1 increases, or can decrease when the duty cycle of the PWM signal PWM1 decreases.

An example of the configuration of the dimmer 1502 of FIG. 15 is shown in FIG. 16 according to an embodiment of the present invention. FIG. 16 is described in combination with FIG. In the example of FIG. 16, the clock generator 1504 includes a comparator, and the dimming indicator 1526 includes a clock counter. The PWM generator 530 includes a sawtooth signal generator and a comparator. The clock generator 1504 compares the periodic signal 1454 indicating the AC signal V _IN with the voltage reference V _REF to generate a clock signal 1544. In one embodiment, each pulse of the clock signal 1544 corresponds to a cycle of the periodic signal 1454. As an example, when the frequency of the AC signal V _IN is 50 Hz, the frequency of the periodic signal 1454 is 100 Hz, and the frequency of the clock signal 1544 is also 100 Hz. In one embodiment, when the result of the wave counting of the AC signal V _IN exceeds a predetermined number, such as 100, the dimming indicator 1526 sets the dimming value of the digital output 1548 by a predetermined number (e.g., only 1). ) Increase and restart counting. Accordingly, the D / A converter 528 can control the dimming signal such as the duty cycle of the reference signal REF or the PWM signal PWM1 from the first preset level to the second preset level. In such an example, the dimming value can be increased by 1 every second, and thus the light output of the LED light source 1412 can be increased by a predetermined amount every second.

  Returning to FIG. 15 described in combination with FIG. 16, during operation, when the user first turns on the power switch 304, the dimming indicator 1526 converts the digital output 1548 to a predetermined dimming value such as the maximum dimming value. Can be set to a value. As an example, in the analog dimming mode, the reference signal REF is preset to a maximum level, for example equal to the reference signal REF1. In another example, in the burst dimming mode, the duty cycle of the PWM signal PWM1 is preset to 100%. Therefore, the LED light source 1412 of FIG. 14A can emit the maximum light intensity / luminance.

When the user turns off the power switch 304 and then contacts the power switch 304 within a predetermined time interval ΔT, the trigger monitoring unit 1506 detects a positive edge following the negative edge of the voltage at the terminal CLK. Therefore, the trigger monitoring unit 1506 generates the first pulse based on the operation of the power switch 304. With the first pulse, the wave count of the AC signal V _IN can adjust the dimming signal such as the reference signal REF or the PWM signal PWM1. In one embodiment, in response to the first pulse, the dimming indicator 1526 increases the digital output 1548 from the minimum dimming value, and the light output of the LED light source 1412 increases from the corresponding minimum intensity / luminance. . When the dimming signal is adjusted to a desired level, such as the light output of the LED light source 1412 is adjusted to a desired intensity / luminance, the user turns off the power switch 304 and then turns on the power switch within a predetermined time interval ΔT. 304 can be touched. Therefore, the trigger monitoring unit 1506 generates the second pulse based on the operation of the power switch 304. The second pulse can override the wave counting of the AC signal V _IN . Therefore, the dimming indicator 1526 maintains the dimming signal at a desired level and maintains the light output of the LED light source 1412 at a desired intensity / luminance.

  Furthermore, when the user again turns off the power switch 304 and then contacts the power switch 304 within a predetermined time interval ΔT, the dimming indicator 1526 resumes counting the clock signal 1544 and the digital output 1548 Again, the minimum dimming value can be increased. However, in one embodiment, when the digital output 1548 reaches the maximum dimming value, the dimming indicator 1526 can stop counting the clock signal 1544 and maintain the digital output 1548 at the maximum dimming value. Therefore, the light output of the LED light source 1412 remains at the maximum intensity / luminance. Next, when the user again turns off the power switch 304 and then turns on the power switch 304 within a predetermined time interval ΔT, the trigger monitoring unit 1506 causes the dimming indicator 1526 to resume counting the clock signal 1544. can do. The dimming indicator 1526 can again increase the digital signal 1548 from the minimum dimming value.

  FIG. 17 shows an example diagram illustrating the operation of the light source drive system 1400 of FIG. 14A, according to one embodiment of the invention. FIG. 17 is described in combination with FIG. 14A, FIG. 15, and FIG.

  First, assume that power switch 304 is off. In one embodiment, during operation, for example, when the user first turns on the power switch 304, the LED light source 1412 is powered by the regulated power from the power converter 1410 to generate the initial light output. In the analog dimming mode, the initial light output can be determined by the initial voltage of the reference signal REF. In the burst dimming mode, the first light output can be determined by the first duty cycle (eg, 100%) of the PWM signal PWM1. The reference signal REF and the PWM signal PWM1 can be generated according to the dimming value of the dimming indicator 1526. Thus, the first voltage at REF and the first duty cycle of PWM1 can be determined by the first dimming value (eg, 10) supplied by dimming indicator 1526.

  To adjust the light output of the LED light source 1412, the user can perform a first set of operations on the power switch 304. When the first power-on operation that continues within the predetermined time interval ΔT from the first power-off operation of the power switch 304 is detected, a dimming request signal is generated. As a result, the dimming request signal including the positive edge 1706 following the negative edge 1704 of the voltage at the terminal CLK can be detected. In response to the dimming request signal, the trigger monitoring unit 1506 can generate a pulse TRIG. Therefore, the dimming indicator 1526 can count the clock signal 1544. In the example of FIG. 17, the dimming indicator 1526 increases the dimming value from a minimum value such as 1 and increases the dimming value by 1 in response to three pulses of the clock signal 1544. However, the present invention is not limited to this. In another embodiment, the dimming indicator 1526 can increase the dimming value by 2, 3, or other numbers in response to a predetermined number of pulses of the clock signal 1544. In yet another example, the dimming indicator 1526 decreases the dimming value from a predetermined value such as 10, and in response to a predetermined number of pulses of the clock signal 1544, the dimming value is 1, 2, or other It can be reduced by a number.

  In one embodiment, in the analog dimming mode, the D / A converter 528 reads the dimming value from the dimming indicator 1526 and increases the voltage of the reference signal REF in response to the increase in the dimming value. In one embodiment, in burst dimming mode, the D / A converter 528 reads the dimming value from the dimming indicator 1526 and increases the duty cycle of the PWM signal PWM1 in response to the dimming value increase ( For example, increase by 10% each time). Accordingly, the light output of the LED light source 1412 is adjusted.

  If the desired light output is reached before the dimming value reaches a maximum value such as 10, the user can end the adjustment process by performing a second set of actions on the power switch 304. When a second power-on operation that continues within a predetermined time interval ΔT from the second power-off operation of the power switch 304 is detected, a dimming end signal is generated. As a result, it is possible to detect the dimming end signal including the positive edge 1710 following the negative edge 1708 of the voltage at the terminal CLK. Upon detecting the dimming end signal, the trigger monitoring unit 1506 can generate a pulse TRIG. Therefore, the dimming indicator 1526 becomes invalid and holds the dimming value. Therefore, in the analog dimming mode, the voltage of the reference signal REF can be held at a desired level. In the burst dimming mode, the duty cycle of the PWM signal PWM1 can be held at a desired value. Therefore, the light output of the LED light source 1412 can be maintained at a desired level.

  To further adjust the light output of the LED light source 1412, the user can perform a third set of operations on the power switch 304. When a third power-on operation that continues within a predetermined time interval ΔT from the third power-off operation of the power switch 304 is detected, a dimming request signal is generated. As a result, it is possible to detect the dimming request signal including the positive edge 1714 following the negative edge 1712 of the voltage at the terminal CLK. Therefore, the dimming control circuit 1408 adjusts the light output of the LED light source 1412 through adjusting the dimming level by counting the clock signal 1544.

  FIG. 18 shows an example diagram illustrating the operation of the light source drive system 1400 of FIG. 14A, according to one embodiment of the invention. FIG. 18 is described in combination with FIG. 14A, FIG. 15, FIG. 16, and FIG.

  As in the example of FIG. 17, in the example of FIG. 18, first assume that the power switch 304 is off. In one embodiment, during operation, for example, when the user first turns on the power switch 304, the LED light source 1412 is powered by the regulated power from the power converter 1410 to generate the initial light output.

  To adjust the light output of the LED light source 1412, the user can perform a first set of operations on the power switch 304. When a first power-on operation that continues within a predetermined time interval ΔT from the first power-off operation is detected, a dimming request signal is generated. As a result, it is possible to detect the dimming request signal including the positive edge 1806 following the negative edge 1804 of the voltage at the terminal CLK. The dimming control circuit 1408 adjusts the adjusted power to the LED light source 1412 through adjusting the dimming level by counting the clock signal 1544.

  In the example of FIG. 18, when the dimming value increases to its maximum value, such as 10, the dimming indicator 1526 can maintain the dimming value at its maximum value. In another embodiment, the dimming value is reduced from its maximum value, such as 10. When the dimming value decreases to its minimum value, such as 1, dimming indicator 1526 can maintain the dimming value at its minimum value. Thus, in analog dimming mode, the voltage of the reference signal REF remains at its maximum level or its minimum level, and in burst dimming mode, the duty cycle of the PWM signal PWM1 is its maximum duty cycle such as 100% or It remains at its minimum duty cycle such as 10%. The light output of the LED light source 1412 remains at its corresponding maximum level or its minimum level.

  The user can resume the adjustment process by performing a second set of actions on the power switch 304. When a second power-on operation that continues within a predetermined time interval ΔT from the second power-off operation is detected, a dimming request signal is generated. As a result, a dimming request signal including the positive edge 1810 following the negative edge 1808 of the voltage at the terminal CLK can be detected, and the dimming control circuit 1408 counts the dimming level by counting the clock signal 1544. Through adjustment, the adjusted power to the LED light source 1412 can be adjusted.

FIG. 19 shows an example of a schematic diagram of an LED light source drive system 1900, according to one embodiment of the present invention. FIG. 19 is described in combination with FIG. 10 and FIG. 14A. Elements having the same reference numerals as in FIGS. 10 and 14A have the same functions. Similar to drive system 1400 of FIG. 14A, drive system 1900 includes power conversion circuits such as AC / DC converter 306 and DC / DC converter 1910, and dimming control circuits such as dimming controller 1908. In the example of FIG. 19, the DC / DC converter 1910 and dimming controller 1908 have the same functions as the DC / DC converter 310 and dimming controller 1008 described in FIG. Further, the dimming controller 1908 receives the periodic signal 1454, for example, via the terminal CLK, and counts the sine wave of the AC signal V _IN by counting the cycle of the periodic signal 1454. The dimming controller 1908 can adjust the adjusted power I _REG to the LED light source 1412 by counting the sine wave of the AC signal V _IN . The adjustment process of the adjusted power I _REG is the same as the process described in FIG. 14A. In one embodiment, the control switch Q16 can be incorporated in the dimming controller 1908.

  FIG. 20 shows an example of the configuration of the dimming control circuit 1908 of FIG. 19 according to an embodiment of the present invention. FIG. 20 is described in combination with FIG. 11, FIG. 15, and FIG. Elements having the same reference numerals as those in FIGS. 11, 15, and 19 have the same functions.

  In the example of FIG. 20, the configuration of the dimming control circuit 1908 is the same as the configuration of the dimming controller 1008 of FIG. 11 except for the configurations of the trigger monitoring unit 1506 and the dimmer 1502. The trigger monitoring unit 1506 and the dimmer 1502 have the same functions as the dimming control circuit 1408 in FIG.

  FIG. 21 shows an example of a block diagram of an LED light source driving system 2100 according to an embodiment of the present invention. FIG. 21 is described in combination with FIG. 14A, FIG. 15, FIG. 19, and FIG. Elements having the same reference numerals as in FIGS. 14A and 19 have similar functions.

In one embodiment, drive system 2100 includes a plurality of power converters 2110 that provide power to a plurality of LED sources, such as LED strings 2112 and 2118. The drive system 2100 controls the adjusted power such as the adjusted currents I _REG1 and I _REG2 supplied to the LED source by counting the wave of the AC signal _VIN , such as counting the cycle of the periodic signal 1454 The dimming controller 2108 is further included. The power converter 2110 can have the same function and / or configuration as the power converter 1410 of FIG. 14A or the power converter 1910 of FIG. The dimming controller 2108 can have the same function and / or configuration as the dimming controller 1408 (of FIGS. 14A and 15) or the dimming controller 1908 (of FIGS. 19 and 20).

Two LED strings are shown in FIG. 21, which are examples for illustrative purposes. The drive system 2100 can supply power to other numbers of LEDs or LED strings. Accordingly, the drive system 2100 includes a corresponding number of DC / DC converters and dimming controllers. Advantageously, by adjusting the wave of the AC signal _VIN to adjust the light output of multiple LED sources, the process of adjusting the light output of the LED sources is synchronized with each other. In other words, the variation in the light output of the LED source can be made substantially the same. Thus, the LED sources can emit approximately the same light intensity / luminance. In addition, the internal oscillator circuit can be omitted from the dimming controller 2108.

  FIG. 22 shows a flowchart of an example method for controlling dimming of an LED light source, according to an embodiment of the present invention. FIG. 22 is described in combination with FIG. 14A, FIG. 15, FIG. 16, FIG. 17, FIG. 18, FIG.

In block 2202, the AC signal V _IN is transferred through the power switch 304. In block 2204, the dimming controller generates a drive signal CTRL in response to a set of operations of the power switch 304. In block 2206, the dimming controller adjusts the drive signal CTRL by counting the waves of the AC signal V _IN to control the dimming of the LED light source 1412. In block 2208, the drive signal CTRL controls the control switch Q16 that is coupled to the LED light source 1412.

  Accordingly, embodiments according to the present invention provide controllers, systems, and methods for controlling dimming of LED light sources. In one embodiment, the drive system can include a plurality of dimming controllers that adjust the light output of the corresponding LED light sources. Each dimming controller can count waves such as a sine wave of the AC input voltage from the AC power supply and respond to a predetermined number of waves of the AC input voltage to determine the light output of the corresponding LED source Can be increased or decreased by the amount of. Advantageously, dimming of multiple LED sources can be synchronized with each other, and multiple LED sources can emit approximately the same light intensity / luminance.

  Although the foregoing description and drawings represent embodiments of the present invention, various additions, modifications and replacements may be made therein without departing from the spirit and scope of the principles of the invention as defined in the appended claims. It will be appreciated that can be done. The invention is not limited to the forms, structures, configurations, ratios, materials, elements, elements, and many others used in the practice of the invention, specifically tailored to the particular environment and operating requirements without departing from the principles of the invention. One skilled in the art will appreciate that it can be used with modification. Accordingly, the embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive, and the scope of the present invention is defined by the appended claims and their legal It is shown by an equivalent thing and is not limited to the above description.

100 Conventional LED drive circuit
102 Power converter
104 Power switch
106 LED string
200 Conventional LED drive circuit
208 linear LED 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 string
314 Current sensor
400 Light source drive circuit
502 dimmer
504 Pulse signal generator
506 Trigger monitoring unit
508 start-up and undervoltage lockout (UVL) circuits
510 operational amplifier
512 MOSFET
514 MOSFET
515 MOSFET
516 comparator
518 comparator
520 SR flip-flop
522 SR flip-flop
524 AND gate
526 counter
528 D / A converter
530 PWM generator
532 Current source
534 comparator
536 pulse signal
538 Control signal
540 switch
541 switch
542 switch
602 Signal waveform of LED current passing through LED string
900 Flowchart of how to adjust the light source output
1000 Light source drive circuit
1008 Dimming controller
1102 Dimmer
1104 clock generator
1106 Trigger monitoring unit
1126 counter
1204 negative edge
1206 Positive edge
1208 Negative edge
1210 positive edge
1300 Flowchart of the method of adjusting the power of the light source
1400 LED light source drive system
1404 Power switch
1408 Dimming controller
1410 DC / DC converter
1412 LED light source
1414 diode
1424 capacitor
1428 current sensor
1433 Common node
1454 Periodic signal
1480 elements
1502 dimmer
1504 Trigger circuit, clock generator
1506 Trigger monitoring unit
1526 Dimming indicator
1536 pulse signal
1544 clock signal
1548 digital output
1550 error amplifier
1704 Negative edge
1706 Positive edge
1708 negative edge
1710 positive edge
1712 Negative edge
1714 Positive edge
1804 Negative edge
1806 Positive edge
1808 Negative edge
1810 positive edge
1900 LED light source drive system
1908 Dimming controller
1910 DC / DC converter, power converter
2100 LED light source drive system
2108 Dimming controller
2110 power converter
2112 LED string
2118 LED string
Flow chart of the method to control dimming of 2200 LED light source

Claims (17)

A controller for controlling dimming of a plurality of light emitting diode (LED) light sources,
A plurality of control terminals, the control terminal, and supplies a drive signal for controlling the corresponding one of the control switches of the plurality of control switches for coupling each of the plurality of LED light sources, whereby said plurality of A plurality of control terminals operable to control the dimming of a corresponding one of the LED light sources ; and
A plurality of dimming control circuits respectively coupled to the plurality of control terminals, wherein each of the dimming control circuits generates the drive signal according to a plurality of operations of a power switch that transfers an alternating current (AC) signal; A plurality of dimming control circuits that can operate to adjust the dimming signal by counting a plurality of waves of the AC signal and to adjust the driving signal. ,
The dimming control circuit includes:
A trigger monitoring unit that is operable to monitor the power switch and generate a pulse in response to detecting the operation of the power switch;
A dimmer coupled to the trigger monitoring unit and operable to count the number of the waves based on the pulse and adjust the dimming signal according to the number of waves , The controller.   The controller of claim 1, wherein the AC signal includes an AC voltage supplied by an AC power source.   2. The controller according to claim 1, wherein the dimming control circuit counts the waves of the AC signal by counting a plurality of pulses of a clock signal.   4. The controller according to claim 3, wherein the dimming control circuit compares the periodic signal indicating the AC signal with a voltage reference to generate the clock signal.   2. The controller according to claim 1, wherein the dimming control circuit controls the dimming signal from a first preset level to a second preset level when the number of waves exceeds a predetermined number. When the trigger monitoring unit generates a first pulse based on the operation, the first pulse enables the counting of the number of waves and causes the dimmer to send the dimming signal to a certain level. To adjust
When the trigger monitoring unit generates a second pulse based on the operation, the second pulse invalidates the count of the number of waves and sends the dimming signal to the dimmer at the level. 2. The controller of claim 1, wherein the controller is maintained.   The dimming signal includes a reference signal, and the controller controls the dimming of the LED light source by comparing the reference signal with a monitoring signal indicating a current passing through the LED light source. Item 2. The controller according to item 1.   2. The controller according to claim 1, wherein the dimming signal includes a pulse width modulation (PWM) signal, and the controller controls the dimming of the LED light source according to the PWM signal and the pulse signal.   2. The controller according to claim 1, wherein the operation of the power switch includes a step of connecting the power switch that continues within a predetermined time interval from the step of turning off the power switch. A method of controlling dimming of a plurality of light emitting diode (LED) light sources,
Transferring an alternating current (AC) signal through a power switch;
Generating a plurality of drive signals in response to a plurality of operations of the power switch;
Adjusting the dimming signal by counting the plurality of waves of the AC signal to control the dimming of the plurality of LED light sources, respectively, and adjusting the plurality of drive signals, respectively ;
And a step of controlling the plurality of control switches for coupling each of the plurality of LED light sources by the plurality of driving signals, respectively,
The step of adjusting each of the plurality of drive signals includes:
Monitoring the power switch and generating a pulse in response to detecting the operation of the power switch;
Counting the number of waves based on the pulses and adjusting the dimming signal according to the number of waves. The step of adjusting each of the plurality of drive signals includes:
Comparing the periodic signal indicative of the AC signal with a voltage reference to generate a clock signal;
11. The method of claim 10, comprising counting the waves of the AC signal by counting a plurality of pulses of the clock signal. The step of adjusting each of the plurality of drive signals includes:
11. The method of claim 10, comprising controlling the dimming signal from a first preset level to a second preset level when the number of waves exceeds a predetermined number. The step of generating the plurality of drive signals comprises:
Generating a plurality of first pulses or a plurality of second pulses based on the operation,
The step of adjusting each of the plurality of drive signals includes:
When generating the first pulse based on the operation, enabling the counting of the number of waves and adjusting the dimming signal to a certain level;
11. The method of claim 10, comprising invalidating the count of the number of waves and maintaining the dimming signal at the level when generating the second pulse based on the operation. A system for supplying power to a plurality of light emitting diode (LED) light sources,
A plurality of converter circuits, each converter circuit receiving an alternating current (AC) signal through a power switch and operating to supply regulated power to a corresponding one of the plurality of LED light sources. A plurality of conversion circuits,
A plurality of dimming control circuits respectively coupled to the plurality of conversion circuits , each dimming control circuit generating a dimming signal according to a plurality of operations of the power switch, and a plurality of waves of the AC signal; Ki de be operable to adjust the dimming signal by counting the dimming of a corresponding one of the LED light sources of the plurality of LED light sources is controlled in response to the dimming signal A plurality of dimming control circuits,
The dimming control circuit includes:
A trigger monitoring unit that is operable to monitor the power switch and generate a pulse in response to detecting the operation of the power switch;
A dimmer coupled to the trigger monitoring unit and operable to count the number of the waves based on the pulse and adjust the dimming signal according to the number of waves ,system. The conversion circuit includes:
An AC / DC converter that converts AC power to DC power;
A DC / DC converter that couples to the AC / DC converter and converts the DC power to the adjusted power by controlling a control switch in series with the LED light source in response to the dimming signal; 15. The system according to claim 14, comprising.   The dimming control circuit compares the periodic signal indicating the AC signal with a voltage reference, generates a clock signal, and counts the waves of the AC signal by counting a plurality of pulses of the clock signal. 15. The system of claim 14, wherein:   15. The system of claim 14, wherein the dimming control circuit controls the dimming signal from a first preset level to a second preset level when the number of waves exceeds a predetermined number.