TWI507082B - Controller and method for powering light emitting diode light source and portable lighting device - Google Patents

Description

Controller and method for controlling power supply of light-emitting diode light source, and portable lighting device

The present invention relates to a lighting device, and more particularly to a portable lighting device having a power management control circuit.

FIG. 1 is a block diagram of a conventional power supply system 100. Power system 100 includes a first power source (eg, adapter 102) and a second power source (eg, battery 110). The power supply system 100 also includes a direct current/direct current (DC/DC) converter 104, a charger 106, a switch 103, a switch 105, and a load, such as a light emitting diode 108. The adapter 102 is coupled to an AC power source (eg, a 120 volt commercial supply voltage) and converts an AC voltage from the AC power source to a DC voltage V _AD .

In operation, when switch 103 is turned "on" and switch 105 is turned off, power system 100 operates during the battery charging process. The charger 106 receives one of the DC voltages V _AD provided by the adapter 102 and provides suitable charging power to the battery 110. The DC/DC converter 104 receives the DC voltage V _AD and provides the adjusted power to the LEDs 108. When the switch 105 is turned on and the switch 103 is turned off, the battery 110 supplies power to the light emitting diode 108 via the DC/DC converter 104.

However, there are two power supply chains in the conventional power supply system 100. One power supply chain includes a charger 106 and the other power supply chain includes a DC/DC converter 104. These two power chains increase the power consumption of the power system 100, which in turn reduces the power efficiency of the power system 100. The two power chains also increase the complexity of the power system 100. In addition, since the charger 106 and the DC/DC converter 104 are used at the same time, the printed circuit board of the power supply system 100 The corresponding increase in inch increases the cost of the power system 100.

Traditional portable lighting devices, such as household flashlights, are typically illuminated with incandescent lamps. In recent years, LEDs have evolved into light sources for liquid crystal display (LCD) backlights, home lighting fixtures, and street lamps. Since LEDs have better luminous efficiency and longer service life than incandescent lamps, the use of LEDs as light sources for flashlights is also becoming common.

Traditional flashlights require a battery as a power source. However, at the moment the flashlight is turned on, the spur applied to the luminaire will damage the luminaire, which in turn reduces the life of the luminaire. The most common solution is to add a current limiting resistor between the luminaire and the battery to avoid large currents that are applied to the luminaire instantaneously and damage the luminaire. However, the increased power consumption due to the addition of resistors in the circuit can severely shorten battery life.

When the LED is turned on, there is usually a forward voltage between 3.2 volts and 4.0 volts. A household alkaline battery typically provides a voltage of 1.5 volts. Therefore, in the existing flashlights using LEDs as lamps, a household alkaline battery usually only supplies 1.5V, so three alkaline batteries are needed to supply power to the LEDs.

Figure 7A shows a schematic diagram of a circuit 700 within a conventional flashlight. The circuit 700 uses a battery pack 710 formed of three alkaline batteries connected in series as a power source for the circuit 700. Each alkaline battery provides 1.5V. Battery pack 710 is powered by switch 720 to drive light source 730 (eg, an LED). In one embodiment, light source 730 has a forward voltage of 3.2V and an on current of 100 mA. Circuit 700 provides a current limiting resistor 740 (eg, 13 ohms) between source 730 and battery pack 710.

In operation, the current limiting resistor 740 consumes 0.13 W while the source is The 730 consumes 0.32W. It can be seen that the power of the light source 730 is only 71% of the total power provided by the battery pack 710. In other words, part of the energy provided by the battery pack 710 is wasted on the current limiting resistor 740. Therefore, the battery pack 710 needs to supply more energy to maintain the brightness of the light source 730, thereby accelerating the life of the battery pack 710.

If the source 730 has a forward voltage of 4.0V when turned on due to process or other factors, the current limiting resistor 740 between the source 730 and the battery pack 710 will limit the current flowing through the source 730 to approximately 38.5 mA. In other words, at this time, the brightness of the light source 730 will be only 38.5% of the original design planned brightness (i.e., the current flowing through the light source 730 is 100 mA). On the other hand, if the current limiting resistor 740 is changed to 5 ohms, although the luminance of the light source 730 having a forward voltage of 4.0 V can be made to the original designed luminance (i.e., the current flowing through the light source 730 is 100 mA), For LEDs with a low forward voltage (eg 3.2V), overcurrent can occur, causing an increase in the current through these LEDs (eg 260 mA), which will result in a reduced lifetime of these LEDs.

Figure 7B shows a performance diagram 750 of the circuit of Figure 7A. The conventional circuit uses two 1.5V alkaline batteries with a current limiting resistor to drive an LED with a current of 100mA. As shown in performance map 750, the battery life using conventional circuitry is approximately 100 minutes.

In addition, if the user replaces LEDs of different powers, such a circuit using a current limiting resistor will face practical application limitations. For example, if the user wants to obtain 10 times the power and replace the LED with the rated current of 100 mA with the LED of 1 A, then since the current limiting resistor is preset and fixed, the current flowing through the LED will not change, so Unable to meet user expectations. At the same time, because the configuration of the battery pack needs to consider the mechanism design of the flashlight at the same time, It is usually not possible to change the number of batteries at will to change the power supply. In summary, for battery-powered flashlight applications, such current-limiting resistors are both impractical and inefficient, plaguing circuit design and application flexibility.

An object of the present invention is to provide a portable lighting device comprising: a power source for providing a voltage; a load circuit comprising a light emitting diode light source; and a controller for receiving the voltage and according to the one indicating the voltage The sensing signal adjusts a current flowing through the light emitting diode source, wherein when the sensing signal indicating the voltage is higher than a first voltage level, the controller will flow through the light emitting diode source The current is adjusted to a first current level, and wherein the controller adjusts the current flowing through the light emitting diode source to a second when the sensing signal indicating the voltage is lower than a second voltage level a current level, and wherein the controller adjusts the current flow through the light emitting diode source when the sense signal indicative of the voltage is between the first voltage level and the second voltage level The sensing signal changes.

The invention also provides a method for supplying power to a light emitting diode light source, comprising: a power supply to a light emitting diode light source under control of a controller; the controller receiving a sensing indicating a voltage of the power source a signal; when the sensing signal indicating the voltage of the power source is higher than a first voltage level, the controller adjusts a current flowing through the light emitting diode source to a first current level; when indicating The sensing signal of the voltage of the power source is lower than The controller adjusts the current flowing through the LED source to a second current level at a second voltage level; and the sensing signal indicating the voltage of the power source is at the first voltage level The controller adjusts the current flowing through the light emitting diode source to follow the sense signal change when it is between the second voltage level and the second voltage level.

The invention also provides a controller for controlling power supply to a light emitting diode light source, comprising: a power input end coupled to a power source for receiving a voltage from the power source; and a sensing end coupled to the power source for receiving an indication a sensing signal of the voltage of the power source; and a feedback terminal receiving a feedback signal indicating a current flowing through the light emitting diode source, wherein the controller is based on the feedback signal and the sensing The signal generates a reference signal indicating a target current flowing through the light emitting diode light source, and adjusts a current flowing through the light emitting diode light source according to the feedback signal and the reference signal, when the voltage of the power source is indicated When the sensing signal is higher than a first voltage level, a voltage of the reference signal is at the first voltage level; when the sensing signal indicating the voltage of the power source is lower than a second voltage level, The voltage of the reference signal is at the second voltage level; when the sense signal indicating the voltage of the power source is between the first voltage level and the second voltage level, the voltage of the reference signal follows The Detection signal changes linearly.

A detailed description of the embodiments of the present invention will be given below. Although the invention will be described in connection with the embodiments, it should be understood that this is not intended to mean the invention Limited to these embodiments. Rather, the invention is to cover various modifications, equivalents, and equivalents of the invention as defined by the scope of the appended claims.

In addition, in the following detailed description of the embodiments of the invention However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail in order to facilitate the invention.

2 is a block diagram of a power supply system 200 in accordance with one embodiment of the present invention. In the embodiment shown in FIG. 2, power system 200 includes a first power source (eg, adapter 202), a second power source (eg, battery 210), switches 203, 205, and 207, a controller 206, and a load, such as a light emitting diode. Polar body 208. Adapter 202 receives an AC voltage or a DC voltage and outputs a DC voltage (eg, adapter output voltage V _AD ). In one embodiment, power system 200 can selectively operate in a charging mode or a load powering mode. The controller 206 is coupled to the adapter 202 and the battery 210 and compares the adapter output voltage V _AD with the battery voltage V _BAT . When the adapter output voltage V _{AD is} greater than the battery voltage V _BAT , the controller 206 controls the adapter 202 to charge the battery 210 via the switches 203 and 207 in the charging mode. More specifically, in the charging mode, the controller 206 turns off the switch 205 and alternately turns on the switches 203 and 207, thereby causing the adapter 202 to charge the battery 210. The adapter 202 can steadily charge or voltage-charge the battery according to the state of the battery 210 (eg, battery voltage). When the battery voltage V _{BAT is} greater than the adapter output voltage V _AD , the controller 206 controls the battery 210 to power the light emitting diode 208 via the switches 205 and 207 in the load power mode. More specifically, in the load power mode, the controller 206 turns off the switch 203 and alternately turns on the switches 205 and 207, thereby causing the battery 210 to power the light emitting diode 208. In one embodiment, controller 206 can be integrated with integrated circuits (referred to herein as control circuit 220) along with switches 203, 205, and 207. Although the power supply system 200 is described in connection with the adapter 202, the battery 210, and the light emitting diode 208, the present invention is not limited thereto. Adapter 202 and battery 210 may be replaced by other types of power sources; light emitting diodes 208 may also be replaced by multiple LED light sources or other types and numbers of light sources or loads.

In one embodiment, controller 206 includes outputs CTR1, CTR2, and CTR3. The output 埠CTR1 is used to control the switch 203; the output 埠CTR2 is used to control the switch 205; and the output 埠CTR3 is used to control the switch 207. Switches 203, 205, and 207 can be N-channel metal oxide semiconductor field effect transistors (MOSFETs). When the output control signal of the output 埠CTR1, CTR2 or CTR3 is logic high, the corresponding switch 203, 205 or 207 is turned on; when the output control signal of the output 埠CTR1, CTR2 or CTR3 is logic low, the corresponding Switch 203, 205 or 207 is open. Controller 206 also includes inputs 埠VAD, VBAT, ICHG, VLED, ILED, and UVLS. The input 埠VAD is used to detect the adapter output voltage V _AD ; the input 埠VBAT is used to detect the battery voltage V _BAT ; with the cooperation of 埠VBAT, the input 埠ICHG detects the charging current of the battery 210 by monitoring the voltage V ₂₁₆ across the sense resistor 216 I _CHG ; 埠VLED receives a signal indicating the anode voltage V _LED of the light-emitting diode 208; with the cooperation of the 埠VLED, the 埠ILED detects the current flowing through the light-emitting diode 208 by monitoring the voltage V _{212 of the} sense resistor 212. _LED ; 埠UVLS is coupled to voltage divider resistor 230 and receives a voltage V _UVLS indicative of battery voltage V _BAT (eg, voltage V _{UVLS is proportional} to battery voltage V _BAT ). In one embodiment, controller 206 adjusts an adjustable reference voltage V _ADJ based on voltage V _UVLS . The controller 206 regulates the current I _LED flowing through the LED 208 in accordance with the adjustable reference voltage V _ADJ . The controller 206 also further includes a 埠 STATUS for indicating the status of the battery 210 (eg, whether the battery 210 is fully charged).

When the adapter 202 is coupled to a power source (eg, a 120 volt commercial supply voltage), the adapter 202 converts the supply voltage to a DC voltage V _AD . The controller 206 compares the adapter output voltage V _AD and the battery voltage V _BAT output by the adapter 202. In one embodiment, power supply system 200 operates in a charging mode when adapter output voltage V _{AD is} greater than battery voltage V _BAT and battery 210 is not fully charged (eg, battery voltage V _{BAT is} less than a threshold).

3A shows an exemplary timing diagram of the output control signals of the outputs 埠CTR1, CTR2, and CTR3 of the controller 206 in the charging mode. As shown in FIG. 3A, the output control signals of the output ports CTR1 and CTR3 are non-superimposed pulse signals, such as pulse width modulation (PWM) signals, to alternately turn on the switches 203 and 207. The output control signal of the output 埠CTR2 is at a logic low level to turn off the switch 205.

As shown in FIG. 2, in the charging mode, switches 203 and 207, inductor 214, and capacitor 213 act as a buck converter to charge battery 210. More specifically, when switch 203 is turned on and switch 207 is turned off, adapter 202 charges battery 210 via inductor 214. Simultaneously, Inductor 214 stores energy. When switch 203 is open and switch 207 is turned on, inductor 214 is discharged to provide power to battery 210.

In one embodiment, controller 206 detects battery voltage V _BAT and the charging current of battery 210 to control the charging process. More specifically, in the charging mode, the controller 206 compares the battery voltage V _BAT with a predetermined threshold V _TH , and controls the duty cycle of the switch 203 to adjust the charging power provided by the adapter 202 to the battery 210. When the battery voltage V _{BAT is} less than the predetermined threshold V _TH , the controller 206 controls the switches 203 and 207 to charge the battery 210 at a constant current stage, that is, to charge the battery 210 at a constant current. For example, when the voltage V _{216 of the} sense resistor 216 is greater than the reference voltage V _BATREF , that is, when the charge current I _{CHG is} greater than the predetermined charge current I _BATREF , the controller 206 reduces the charge current I _CHG by reducing the duty cycle of the switch 203 ; When the voltage V _{216 of the} sense resistor 216 is less than the reference voltage V _BATREF , that is, when the charge current I _{CHG is} less than the predetermined charge current I _BATREF , the controller 206 increases the charge current I _CHG by increasing the duty cycle of the switch 203 . However, when the battery voltage V _BAT increases to a predetermined threshold V _TH , the controller 206 controls the switches 203 and 207 to charge the battery 210 during the constant voltage phase, ie, in one embodiment, the charging voltage can remain as predetermined. Limit V _TH .

The controller 206 can also detect parameters of the battery 210, such as voltage, temperature, and current, to determine if an abnormal or undesired condition has occurred. In one embodiment, controller 206 compares the detected battery voltage V _BAT with the overvoltage threshold V _OV to determine if an overvoltage condition has occurred. If the detected battery voltage V _{BAT is} greater than the overvoltage threshold V _OV , the controller 206 turns off the switches 203 and 207, thereby ending the charging of the battery 210.

The controller 206 can also compare a signal indicating the charging current I _CHG of the battery 210 (eg, the voltage V _{216 of the} sense resistor ₂₁₆ ) with a preset threshold V _OC indicating the overcharge current I _OC to determine whether there has ever been The current situation occurs. If the voltage sensing resistor 216 is greater than ₂₁₆ V represents a charging current I _OC preset threshold V _OC, the controller 206 turns off the switch 203 and 207, thereby ending the charging of the battery 210.

The controller 206 can also compare the detection signal from the thermistor (not shown in Figure 2) with the over temperature threshold V _OT to determine if a temperature is too high. If the detection signal is greater than the threshold value V _OT , the controller 206 turns off the switches 203 and 207, thereby ending the charging of the battery 210.

In the charging mode, the controller 206 can also detect the resistance value R _{BAT of the} battery according to the battery voltage V _BAT and the charging current I _CHG as shown in the equation (1): R _BAT =V _BAT /I _CHG (1)

Thus, the controller 206 can determine the battery type based on the resistance value R _BAT of the battery. If the battery type determined by the controller 206 is a non-rechargeable battery (eg, an alkaline battery), the controller 206 ends charging the battery 210 to protect the battery 210 and the power system 200.

In addition, power system 200 can also operate in a load power mode. FIG. 3B shows an exemplary timing diagram of the output control signals of the outputs 埠CTR1, CTR2, and CTR3 of the controller 206 in the load supply mode. As shown in FIG. 3B, the output control signals of the output ports CTR2 and CTR3 are non-superimposed pulse signals, such as PWM signals, for alternately turning on the switches 205 and 207. The output control signal of the output 埠CTR1 is at a logic low level to turn off the switch 203.

In load-powered mode, switches 205 and 207, inductor 214, and capacitors 211 and 213 act as buck-boost converters to power LEDs 208. More specifically, when switch 207 is turned on and switch 205 is turned off, battery 210 charges inductor 214. When the switch 207 is turned off and the switch 205 is turned on, the battery 210 and the inductor 214 together supply power to the light emitting diode 208. In this embodiment, switches 205 and 207 are alternately turned on by an adjustable duty cycle to produce a voltage V ₁ greater than the battery voltage V _BAT at one end of the LED 208. Thus, the voltage V _{208 of the} LED ₂₀₈ is equal to the difference between V ₁ and the battery voltage V _BAT . In one embodiment, the voltage V _{208 of the} LED ₂₀₈ may be greater or less than the battery voltage V _BAT through operation of the buck-boost converter. In this way, the power system 200 can power different types and different numbers of loads, thereby increasing the flexibility of the power system 200.

In one embodiment, controller 206 senses the current I _LED flowing through light emitting diode 208 through the 埠VLED and ILED, and controls the duty cycle of switch 207 to adjust current I _LED based on adjustable reference voltage V _ADJ . A schematic diagram of the relationship between the adjustable reference voltage V _ADJ and the voltage V _UVLS in the power supply system shown in FIG. 2 is shown in FIG. 2A. As shown in FIG. 2A, when the voltage V _{UVLS is} greater than the first threshold value V1, the controller 206 adjusts the adjustable reference voltage V _ADJ to the first constant voltage value V _LED1 . Thus, the controller 206 adjusts the current I _LED flowing through the light emitting diode 208 to the first predetermined current I _LEDREF1 . When the voltage V _{UVLS is} less than the second threshold value V2, the controller 206 adjusts the adjustable reference voltage V _ADJ to the second constant voltage value V _LED2 . Thus, the controller 206 adjusts the current I _LED flowing through the LED 208 to a second predetermined current I _LEDREF2 . When the voltage V _{UVLS is} less than the first threshold V1 but greater than the second threshold V2, the controller 206 adjusts the adjustable reference voltage V _{ADJ to} vary with the voltage V _UVLS . In one embodiment, the adjustable reference voltage V _ADJ varies linearly according to voltage V _UVLS . Since the voltage V _{UVLS is proportional} to the battery voltage V _BAT , the adjustable reference voltage V _ADJ varies linearly according to the battery voltage V _BAT . Thus, the controller 206 adjust the current I _LED according to the battery voltage V _BAT, current I _LED according to the battery voltage V _BAT changes linearly. Advantageously, the working hours of the battery are extended and, therefore, the man-hours of the light-emitting diode 208 are also extended.

As shown in FIG. 2, the controller 206 compares the signal indicative of the current I _LED (eg, the voltage V _{212 of the} sense resistor ₂₁₂ ) with the adjustable reference voltage V _ADJ and controls the switches 205 and 207 based on the comparison. If voltage V _{212 is} greater than adjustable reference voltage V _ADJ (eg, current I _{LED is} increased), controller 206 reduces the duty cycle of switch 207, thereby reducing current I _LED . If voltage V _{212 is} less than adjustable reference voltage V _ADJ (eg, current I _{LED is} decreasing), controller 206 increases the duty cycle of switch 207, thereby increasing current I _LED . Thus, the current I _LED flowing through the light emitting diode 208 is adjusted in accordance with the adjustable reference voltage V _ADJ shown in FIG. 2A.

Advantageously, in charge mode and load supply mode, switches 203, 205 and 207, inductor 214 and capacitors 211 and 213 can be implemented as buck converters and buck-boost converters, thus power system 200 Increased flexibility. Power system 200 can support a variety of different types of loads and power supplies. In power system 200, a power supply chain (e.g., a converter including control circuit 220) replaces two power supply chains (e.g., charger 106 and converter 104) in conventional power supply system 100. Therefore, the power consumption of the power supply system 200 is reduced. Moreover, the complexity of the power system 200 is reduced, thereby enhancing the reliability of the system. In addition, the PCB size of the power system 200 And the cost is also reduced accordingly.

4 is a block diagram showing the structure of the control circuit 220 shown in FIG. 2 in accordance with an embodiment of the present invention. Figure 4 is described in conjunction with Figure 2. As shown in FIG. 4, the control circuit 220 includes an oscillator 411, comparators 413 and 417, error amplifiers 415, 416 and 419, a selector 414, a flip-flop 412, and gates 421 and 422, switches 203, 205 and 207, Adder 431, amplifier 432, ramp signal generator 433, subtractors 434 and 436, and voltage regulator 440.

In one embodiment, comparator 413 compares the battery voltage V _{BAT of 埠VBAT} with the voltage V _{AD of}埠VAD to generate a comparison signal to enable or disable error amplifiers 415, 416, and 419. In one embodiment, the output of a current source 446, the output of the error amplifier 415, and the output of the error amplifier 419 are coupled to a common node. In the embodiment shown in FIG. 4, error amplifier 415 and error amplifier 419 are OR coupled. In one embodiment, in the charging mode (ie, when the adapter output voltage V _{AD is} greater than the battery voltage V _BAT ), the comparator 413 enables the error amplifiers 415 and 419; in the load supply mode (ie, when the adapter output voltage Comparator 413 enables error amplifier 416 when V _{AD is} less than battery voltage V _BAT . When the error amplifier 415 is enabled, a signal indicating the charging current of the battery 210 (for example, a signal indicating the voltage V ₂₁₆ of the resistor 216 output by the subtractor 434) is compared with the reference voltage signal V _BATREF , and is controlled in accordance with the comparison result. The output voltage at the node is V _CMP1 . When the error amplifier 419 is enabled, the battery voltage V _{BAT is} compared with a predetermined threshold V _TH and the output voltage V _CMP1 at the common node is controlled based on the comparison result. When the error amplifier 416 is enabled, a signal indicative of the current flowing through the LED 208 (eg, a signal indicative of the voltage V ₂₁₂ of the sense resistor 212 output by the subtractor 436) and the adjustable reference voltage signal V _{ADJ are} compared. And according to the comparison result, the output voltage V _{CMP2 is controlled} . In one embodiment, the selector 414 is coupled to the error amplifiers 415, 416, and 419, selects the output voltage V _CMP1 or V _CMP2 , and uses the selected output voltage as the output voltage V _{TOP of the} selector 414. More specifically, when the adapter output voltage V _{AD is} greater than the battery voltage V _BAT and the comparator 413 enables the error amplifiers 415 and 419, the selector 414 selects the output voltage V _CMP1 as V _TOP ; when the adapter output voltage V _{AD is} less than the battery voltage V _BAT , when the comparator 413 enables the error amplifier 416, the selector 414 selects the output voltage V _CMP2 as V _TOP . Comparator 417 receives the output voltage V _TOP .

In one embodiment, one end of the adder 413 is coupled to the amplifier 432 to receive the signal V _SEN , the signal V _{SEN is} indicative of the current I _SW flowing through the inductor 214 , and the other end of the adder 413 is coupled to the ramp signal generator 433 . Receive the ramp signal RAMP. Thus, the output V _{SW of} the adder 431 is the sum of the signal V _SEN and the signal RAMP. The comparator 417 compares the output V _{SW of the} adder 431 with the output voltage V _{TOP of the} selector 414 and provides an output to the R terminal of the flip-flop 412 to control the switches 203, 205 and 207. The S terminal of the flip flop 412 is coupled to the oscillator 411 to receive the clock signal CLK. For example, the clock signal CLK has a frequency of 1 MHz. The inverting output terminal QB of the flip-flop 412 controls the switch 207. In addition, the non-inverting output of the flip-flop 412 controls the switches 203 and 205 through the AND gates 421 and 422 in cooperation with the comparator 417.

In operation, when the adapter output voltage V _{AD is} greater than the battery voltage V _BAT , the output of the comparator 413 has a first state (eg, a logic high), thereby causing the power system 200 to operate in a charging mode. In the charging mode, error amplifiers 415 and 419 are enabled and error amplifier 416 is disabled; and gate 422 opens switch 205. The flip-flops 412 and the gate 421 alternately turn on the switches 203 and 207. Based on the comparison of the signal _VSW with the output voltage _VTOP of the comparator 414, the flip-flop 412 also controls the duty cycle of the switches 203 and 207 to control the charging power of the battery 210.

More specifically, in the charging mode, when the battery voltage V _{BAT is} less than the predetermined threshold V _TH , the control circuit 220 controls the switches 203 and 207 to charge the battery 210 during the constant current phase. The error controller 415 compares the signal indicative of the charging current of the battery 210 (eg, the voltage V _{216 of the} resistor ₂₁₆ ) with the reference voltage V _BATREF and controls the output voltage V _CMP1 . The selector 414 selects the output voltage V _CMP1 as the output voltage V _{TOP of the} selector. Thus, the flip-flop 412 controls the duty cycle of the switches 203 and 207 in accordance with the comparison result of the output voltage V _TOP and the signal V _SW .

FIG. 5 is a timing diagram of signals associated with flip-flop 412 of FIG. 4, in accordance with an embodiment of the present invention. When the voltage V _{216 is} less than the reference voltage V _BATREF , that is, when the charging current I _{CHG is} less than the predetermined charging current I _BATREF , the output voltage V _CMP1 increases. The output voltage V _{TOP is} thus increased. As shown in FIG. 5, the duty cycle of the output terminal Q of the flip-flop 412 is increased, and the duty cycle of the switch 203 is increased, thereby increasing the charging current I _{CHG of the} battery 210 accordingly. When the voltage V _{216 is} greater than the reference voltage V _BATREF , that is, when the charging current I _{CHG is} greater than the predetermined charging current I _BATREF , the output voltage V _CMP1 decreases. The output voltage V _{TOP is} thus reduced. As shown in FIG. 5, the duty cycle of the output terminal Q of the flip-flop 412 is reduced, and the duty cycle of the switch 203 is reduced, thereby correspondingly reducing the charging current I _{CHG of the} battery 210. Thus, in the constant current phase, the charging current I _CHG is adjusted to the predetermined charging current I _BATREF .

When the battery voltage V _BAT reaches a predetermined threshold V _TH , the control circuit 220 controls the switches 203 and 207 to charge the battery 210 during the constant voltage phase. In the constant voltage phase, the error amplifier 419 compares the battery voltage V _BAT with a predetermined threshold V _TH and controls the output voltage V _CMP1 . For example, when the battery voltage V _{BAT is} greater than a predetermined threshold V _TH , the output voltage V _{CMP1 is} decreased. Accordingly, the output voltage V _TOP also decreases. Thereby, the duty cycle of the switch 203 is reduced, thereby reducing the charging voltage. Thus, during the constant voltage phase, the charging voltage is adjusted to a predetermined threshold _VTH .

When the adapter output voltage V _{AD is} less than the battery voltage V _BAT , the output of the comparator 413 has a second state (eg, a logic low), thereby causing the power system 200 to operate in a load-powered mode. In load power mode, error amplifiers 415 and 419 are disabled and error amplifier 416 is enabled. In the load power supply mode, the AND gate 421 opens the switch 203. The flip-flop 412 alternately turns on the switches 205 and 207 in cooperation with the gate 422. Based on the comparison of the signal _VSW with the output voltage _VTOP of the comparator 414, the flip-flop 412 also controls the duty cycle of the switches 205 and 207 to control the current flowing through the LED 208.

More specifically, in the load supply mode, the error amplifier 416 compares a signal indicative of the current flowing through the LED 208 (eg, the voltage V _{212 of the} sense resistor ₂₁₂ ) and the adjustable reference voltage V _ADJ . The voltage regulator 440 adjusts the adjustable reference voltage V _ADJ according to the voltage V _UVLS . In one embodiment, the voltage V _UVLS indicates the battery voltage (eg, proportional to the battery voltage V _BAT ). When the voltage V _{UVLS is} greater than the first threshold value V1, the voltage regulator 440 adjusts the adjustable reference voltage V _ADJ to the first constant voltage value V _LED1 . When the voltage V _{UVLS is} less than the second threshold value V2, the voltage regulator 440 adjusts the adjustable reference voltage V _ADJ to the second constant voltage value V _LED2 . When the voltage V _{UVLS is} less than the first threshold value V1 but greater than the second threshold value V2, the voltage regulator 440 adjusts the adjustable reference voltage V _{ADJ to} vary linearly with the voltage V _UVLS . Since the voltage V _{UVLS is proportional} to the battery voltage V _BAT , the adjustable reference voltage V _ADJ varies linearly with the battery voltage V _BAT .

Based on the comparison of the voltage V _{212 of the} sense resistor 212 with the adjustable reference voltage V _ADJ , the error comparator 416 controls the output voltage V _CMP2 . The selector 414 selects the output voltage V _CMP2 as its output voltage V _TOP . Thus, the flip flop 412 controls the duty cycle of the switches 205 and 207 based on the comparison of the output voltage V _TOP with the signal V _SW . When the voltage V _{212 is} less than the adjustable reference voltage V _ADJ , that is, the current I _LED flowing through the light emitting diode 208 decreases, the output voltage V _CMP2 decreases. The output voltage V _TOP is also reduced accordingly. As shown in FIG. 5, the duty cycle of the inverting output terminal QB of the flip-flop 412 is increased, and the duty cycle of the switch 207 is increased, thereby increasing the current I _{LED accordingly} . When the voltage V _{212 is} greater than the adjustable reference voltage V _ADJ , that is, the current I _LED flowing through the light emitting diode 208 increases, the output voltage V _CMP2 increases. The output voltage V _TOP also increases accordingly. As shown in FIG. 5, the duty cycle of the inverting output terminal QB of the flip-flop 412 is reduced, and the duty cycle of the switch 207 is reduced, thereby correspondingly reducing the current I _LED . Thereby, the current I _LED flowing through the light-emitting diode 208 is adjusted in accordance with the adjustable reference voltage V _ADJ . Therefore, when the voltage V _{UVLS is} greater than the first threshold value V1, the current I _LED is adjusted to the first preset current I _LEDREF1 ; when the voltage V _{UVLS is} less than the second threshold value V2, the current I _LED is adjusted to the second The preset current I _LEDREF2 ; when the voltage V _{UVLS is} less than the first threshold value V1 and greater than the second threshold value V2, the current I _LED is adjusted to vary linearly with the battery voltage V _BAT .

When an abnormal or undesired condition (such as an overcurrent, an overvoltage, or an overtemperature) occurs, the control circuit 220 can also protect the power supply system 200 by terminating the charging of the battery. In one embodiment, control circuit 220 may include a comparator (not shown in FIG. 4) that compares battery voltage V _BAT with overvoltage threshold V _OV to determine if an overvoltage condition has occurred. Control circuit 220 can include a comparator (not shown in FIG. 4) that compares voltage V _{216 of} resistor 216 with a preset threshold indicative of overcurrent threshold V _OT to determine if an overcurrent condition has occurred. The control circuit 220 can include a comparator (not shown in FIG. 4) that compares the signal from the thermistor (not shown in FIG. 4) with the over temperature threshold V _OT to determine if there is an over temperature condition. occur. When any abnormal condition occurs, the control circuit 220 turns off the switches 203 and 207 to end charging the battery 210 to protect the power supply system 200.

The control circuit 220 can also detect the type of battery and end charging of the battery 210 when the battery is a non-rechargeable battery (eg, an alkaline battery). Thus, control circuit 220 can protect battery 210 and power system 200.

6 is a flow diagram 600 of a power system operation in accordance with an embodiment of the present invention. FIG. 6 will be described with reference to FIGS. 2 and 4.

In step 602, the power system (eg, power system 200) compares a first voltage of the first power source with a second voltage of the second power source (eg, the battery). When the first voltage of the first power source is greater than the second voltage of the second power source, the power system 200 operates in the first mode (eg, the charging mode). When the first voltage of the first power source is less than the second voltage of the second power source, the power system 200 operates in the second mode (eg, the load power mode).

When the power system 200 is operating in the charging mode, step 604 is entered. In step 604, in an embodiment, the power supply system 200 alternately turns on the first switch (eg, switch 203) and the second switch (eg, switch 207). The third switch (eg, switch 205) is turned off to charge the second power source (eg, battery 210). In step 606, the power supply system 200 adjusts the charging power of the first power source to the second power source by adjusting the duty cycle of the switch 203 and the switch 207.

More specifically, when the voltage of the second power source (eg, battery voltage V _BAT ) is less than a predetermined threshold V _TH , the power system 200 charges the second power source during the constant current phase. In the constant current phase, the power supply system 200 compares the charging current I _CHG with a predetermined charging current I _BATREF . When the charging current I _{CHG is} greater than the predetermined charging current I _BATREF , the power supply system 200 reduces the duty cycle of the first switch 203 to reduce the charging current I _CHG ; when the charging current I _{CHG is} less than the predetermined charging current I _BATREF , the power system 200 increases The duty cycle of the large first switch 203 in turn increases the charging current I _CHG . Therefore, the charging current I _CHG is adjusted to the predetermined charging current I _BATREF .

When the voltage of the second power source (eg, battery voltage V _BAT ) reaches a predetermined threshold V _TH , the power system 200 charges the second power source during the constant voltage phase. During the constant voltage phase, power system 200 compares battery voltage V _BAT with a predetermined threshold V _TH and controls the duty cycle of switches 203 and 207 to adjust the charging voltage to a predetermined threshold V _TH . Therefore, the second power source is charged during the constant voltage phase.

When the power system 200 is operating in the load power supply mode, the process proceeds to step 603. In step 603, power system 200 turns off switch 203 and alternately turns on switch 207 and switch 205 to power the load (eg, light emitting diode 208). In step 605, power supply system 200 adjusts the duty cycle of switch 207 and switch 205 based on the comparison of current I _LED flowing through light emitting diode 208 with adjustable reference current I _ADJ . In one embodiment, the reference current I _ADJ can be adjusted according to a voltage V _UVLS that is proportional to the battery voltage V _BAT . When the voltage V _{UVLS is} greater than the first threshold value V1, the adjustable reference current I _ADJ is adjusted to the first preset current I _LEDREF1 ; when the voltage V _{UVLS is} less than the second threshold value V2, the adjustable reference current I _ADJ is Adjusting to a second preset current I _LEDREF2 ; when the voltage V _{UVLS is} less than the first threshold value V1 and greater than the second threshold value V2, the adjustable reference current I _ADJ is adjusted to follow the voltage V _UVLS and the battery voltage V _BAT Linear change.

When the current I _LED flowing through the light emitting diode 208 is greater than the adjustable reference current I _ADJ , the power supply system 200 reduces the duty cycle of the switch 207 to reduce the current I _LED ; when the current I _{LED is} less than the adjustable reference current I _ADJ The power system 200 increases the duty cycle of the switch 207 to increase the current I _LED . Therefore, the current I _LED is adjusted according to the adjustable reference current I _ADJ . Thus, when the voltage V _{UVLS is} greater than the first threshold value V1, the current I _LED is adjusted to the first preset current I _LEDREF1 ; when the voltage V _{UVLS is} less than the second threshold value V2, the current I _LED is adjusted to the second The preset current I _LEDREF2 ; when the voltage V _{UVLS is} less than the first threshold value V1 and greater than the second threshold value V2, the current I _LED is adjusted to vary linearly with the battery voltage V _BAT .

FIG. 8 is a circuit diagram of a portable lighting device 800 in accordance with an embodiment of the present invention. In one embodiment, the portable lighting device is a flashlight. The portable lighting device 800 includes a battery power source 810 for providing a voltage V _batt , a switch 820 , a light emitting element 830 , a sensing element 840 , a controller 850 , and an inductor L1 . In one embodiment, battery power source 810 is one or more alkaline batteries. In one embodiment, the light emitting element 830 is an LED. In one embodiment, controller 850 is an integrated circuit (IC). In one embodiment, the power input VIN of the controller 850 receives an input voltage from the battery power source 810. The power supply output OUT of the controller 850 provides an output voltage to the light emitting element 830. The sensing terminal ISENSE of the controller 850 receives a feedback signal indicating the power of the light-emitting element 830, and the ground terminal GND is coupled to the ground. The switching output terminal SW is coupled to the power input terminal VIN via the inductor L1.

In one embodiment, the power input VIN of controller 850 is coupled to battery power source 810 via switch 820. The power output OUT of the controller 850 is coupled to the light emitting element 830. The sensing element 840 is connected in series with the light emitting element 830 to generate a feedback signal by sensing the current flowing through the light emitting element 830. The feedback signal is transmitted to the sensing terminal ISENSE of the controller 850.

In one embodiment, inductor L1 acts as an energy storage component of the boost converter. When the switch 820 is turned on, the power input terminal VIN of the controller 850 is coupled to the battery power source 810 to receive the power provided by the battery power source 810. Light emitting component 830 can receive electrical energy via power output OUT of controller 850. When the switch 820 is turned off, the battery power source 810 stops supplying power to the controller 850 and the light emitting element 830. In one embodiment, the controller 850 adjusts the electrical energy supplied to the light-emitting element 830 based on the turn-on and turn-off of the switch 820 and the feedback signal received by the sense terminal ISENSE.

FIG. 9 is a circuit diagram of a portable lighting device 900 in accordance with another embodiment of the present invention. The portable lighting device 900 includes a battery power source 810, a switch 820, a light emitting element 830, a sensing element 840, a controller 950, and an inductor L1. 9 and 8 have the same or similar functions, and will not be described again for the sake of brevity.

In one embodiment, controller 950 is an integrated circuit. In one embodiment, the portable lighting device 900 further includes a DC filter capacitor C1, coupled Connected between the battery power source 810 and the power supply input and output terminal VIN of the controller 950. In one embodiment, the portable lighting device 900 further includes a DC filter capacitor C2 coupled between the light emitting component 830 and the power output OUT of the controller 950. In one embodiment, the controller 950 includes a dimming terminal DIM coupled to the switch 820 to detect the on and off states of the switch 820.

In one embodiment, the controller 950 adjusts the power supplied to the light-emitting element 830 based on the input signal of the dimming terminal DIM, thereby adjusting the brightness of the light-emitting element 830. In one embodiment, controller 950 regulates the electrical energy provided to light-emitting element 830 when switch 820 is turned "on".

FIG. 10A is a circuit diagram of the controller 950 shown in FIG. 10A and 9 have the same or similar functions, and will not be described again for the sake of brevity.

In one embodiment, controller 950 includes a low voltage lockout circuit 1051, a trigger circuit 1052, a clock generator 1053, a reference selector 1054, a dimming unit 1055, a driver 1056, and switches 1057 and 1058. The dimming control operation of the controller 950 in one embodiment will be described below in conjunction with the timing chart shown in FIG. 10B.

When the switch 820 is turned on, the power of the battery power source 810 is applied to the power input terminal VIN of the controller 950. At this time, the light-emitting element 830 is supplied with power according to the rated current. At this time, the reference selector 1054 generates a low frequency pulse width modulation (LPWM) signal. In one embodiment, the LPWM signals have different voltage levels, such as Vmax, V1, V2, etc., where Vmax > V1 > V2. The different voltage levels of the LPWM signals correspond to different brightnesses of the light-emitting elements 830. The dimming unit 1055 adjusts the brightness of the light emitting element 830 according to the voltage level of the LPWM signal. In one embodiment, in the initial state, reference selection The selector 1054 sets the LPWM signal to the highest reference voltage Vmax so that the light-emitting element 830 can reach a maximum (100%) brightness.

When the switch 820 is turned off, the power of the battery power source 810 is stopped from being applied to the controller 950. The trigger circuit 1052 generates a trigger signal having a first negative edge, but the energy stored in the DC filter capacitor C1 is within a certain time before the voltage at the power input terminal VIN is below a low voltage lock threshold. The supply of energy can be maintained. If the switch 820 is turned on again, the trigger signal has a first positive edge, and the trigger signal enables the clock generator 1053 to generate a first clock signal for supply to the reference selector 1054. At this time, the reference selector 1054 generates the first reference voltage V1 and sets the LPWM signal to V1. In one embodiment, the first reference voltage V1 is lower than the highest reference voltage Vmax. For example, the luminance of the light-emitting element 830 can be made 75% of the voltage. The first reference voltage V1 can be set as needed on the application.

In one embodiment, the switch 820 can be turned off again, and the trigger circuit 1052 generates a trigger signal having a second trigger negative edge, but before the voltage at the power supply input terminal VIN falls below a low voltage lock threshold. For a period of time, if the switch 820 is turned on again, the flip-flop has a second positive edge, and the trigger signal will again enable the clock generator 1053 to generate a second clock signal for supply to the reference selector 1054. At this time, the reference selector 1054 generates the second reference voltage V2 and sets the LPWM signal to V2. In one embodiment, the second reference voltage V2 is lower than the first reference voltage V1. For example, the luminance of the light-emitting element 830 can be driven to be 50%. In another embodiment, the second reference voltage V2 is higher than the first reference voltage V1 but lower than the highest reference voltage Vmax, for example, a voltage that can drive the luminance of the light-emitting element 830 to be 80%.

These operations can be repeated. The reference voltages such as the first reference voltage V1, the second reference voltage V2, ... may be set as needed on the application, and may have various variations. For example, the voltage level of the reference voltage may be reduced by high order, for example, 100%, 75%, 50%, 25%; or may be increased from low to high, for example 25%, 50%, 75%, 100%. In one embodiment, the change in the reference voltage can cause the brightness of the light-emitting element 830 to vary linearly, such as 25%, 50%, 75%, and 100%, and the like. In another embodiment, the change in the reference voltage may also cause the change in the reference voltage to cause the brightness of the light-emitting element 830 to vary non-linearly, such as 20%, 30%, 80%, and 100%. In still another embodiment, the reference voltage may be set to change the brightness of the light-emitting element to 100%, 50%, 100% to represent the SOS distress signal.

In one embodiment, the dimming unit 1055 can adjust the output of the power output terminal OUT to control the current flowing through the light emitting element 830 according to the LPWM signal and the feedback signal generated by the sensing element 840 indicating the power of the light emitting element 830. The function of adjusting the brightness of the light-emitting element 830 is achieved. In one embodiment, sensing element 840 is a resistor. In another embodiment, sensing element 840 is a combination of a resistor and a capacitor (not shown in Figure 10A).

In one embodiment, the output of dimming unit 1055 can be amplified by driver 1056. In one embodiment, the output of driver 1056 is coupled to switch 1057 to control switch 1057 to selectively provide power to battery power supply 810 or DC filter capacitor C1 to power supply output OUT of controller 950. In one embodiment, the dimming unit 1055 is a pulse width modulation circuit. In another embodiment, the dimming unit 1055 is a pulse frequency modulation (PFM) circuit.

In one embodiment, the switches 1057, 1058 and the capacitor C2, the inductor L1 forms a boost converter that boosts the voltage at the output of the power supply OUT to a voltage sufficient to drive the light-emitting element 830. In one embodiment, the switching output terminal SW is coupled to the power input terminal VIN via the inductor L1, to the power supply output terminal OUT via the switch 1058 via the switch 1057, and the power supply output terminal OUT is coupled to the DC filter capacitor C2. Therefore, even if the voltage supplied from the battery power source 810 is only 1 V, the voltage of the power source output terminal OUT is increased via the boost converter, and the controller 950 can drive the light-emitting element 830 and adjust the power of the light-emitting element 830, thereby extending the present invention. The life of the battery power source 810 of one embodiment.

In one embodiment, switch 1057 and switch 1058 are metal oxide semiconductor field effect transistors (MOSFETs). In one embodiment, switch 1058 is complementary to switch 1057. In one embodiment, the switch 1057 is an N-channel MOSFET. In one embodiment, switch 1058 is a P-channel MOSFET. In another embodiment, the switch 1058 is a diode.

When the switch 820 is continuously turned off for a period of time until the voltage at the power input VIN is below a predetermined value, such as a low voltage lock (UVLO) threshold, the low voltage lockout circuit 1051 will generate a reset signal. This reset signal resets the clock generator 1053 to turn off the light-emitting element 830. Light-emitting element 830 remains in an off state until switch 820 is again turned "on".

FIG. 11 is a circuit diagram of a portable lighting device 1100 in accordance with yet another embodiment of the present invention. The portable lighting device 1100 includes a battery power source 1110, a switch 820, a light emitting element 830, a sensing unit 840, a controller 1150, and an inductor L2. In one embodiment, battery power source 1110 is one or more alkaline batteries. In one embodiment, the light emitting element 830 is an LED. In one embodiment, controller 1150 is an integrated circuit. Figure 11 and Figure 8 The same elements have the same or similar functions and will not be described again for the sake of brevity.

In one embodiment, inductor L2 acts as an energy storage component of the buck converter. When the switch 820 is turned on, the power input terminal VIN of the controller 1150 is coupled to the battery power source 1110, and the light emitting component 830 receives power via the power output terminal OUT of the controller 1150. When the switch 820 is turned off, the battery power source 1110 stops supplying power to the controller 1150. In one embodiment, the controller 1150 adjusts the electrical energy provided to the light-emitting element 830 based on the on and off states of the switch 820 and the feedback signals received by the sense terminal ISENSE.

FIG. 12 is a circuit diagram of a portable lighting device 1200 in accordance with yet another embodiment of the present invention. The electronic circuit 1200 includes a battery power source 1110, a switch 820, a light emitting element 830, a sensing element 840, a controller 1250, an inductor L2, and capacitors C1 and C2. 12 and FIG. 11 have the same or similar functions, and will not be described again for the sake of brevity.

FIG. 13 is a circuit diagram of the controller 1250 of FIG. Figure 13 will be described in conjunction with Figure 12. The controller 1250 includes a low voltage lockout circuit 1051, a trigger circuit 1052, a clock generator 1053, a reference selector 1054, a dimming unit 1055, a driver 1056, and switches 1357, 1358. 13 and FIG. 10A have the same or similar functions, and will not be described again for the sake of brevity. The dimming control of the controller 1250 is similar to the timing shown in FIG. 10B and will not be described again herein.

In one embodiment, the switches 1357, 1358 and the capacitor C2, the inductor L2 form a buck converter that reduces the voltage at the output of the power supply OUT to a voltage sufficient to drive the light-emitting element 830. In one embodiment, the switching output terminal SW is coupled to the power input terminal VIN via the switch 1357 via the open The switch 1358 is coupled to the ground, and the switch output terminal SW is coupled to the ground via the inductor L2 and the DC filter capacitor C2. The power output terminal OUT is coupled to a node between the inductor L2 and the capacitor C2. Therefore, even if the voltage supplied from the battery power source 1110 is higher than the voltage required to drive the light-emitting element 830 (for example, 6 V), the voltage on the power supply output terminal OUT is lowered via the buck converter, and the controller 1250 can still output the light-emitting element in accordance with the light-emitting element. The lower voltage of the 830 specification drives the light-emitting element 830 and adjusts the power of the light-emitting element 830, thereby saving the power provided by the battery power source 1110, thereby extending the life of the battery power source 1110.

In one embodiment, switch 1357 and switch 1358 are metal oxide semiconductor field effect transistors (MOSFETs). In one embodiment, switch 1358 is complementary to switch 1357. In one embodiment, switch 1357 is an N-channel MOSFET. In one embodiment, switch 1358 is a P-channel MOSFET. In another embodiment, the switch 1358 is a diode.

FIG. 14 is a diagram showing the performance of the portable lighting device 900 shown in FIG. 10A in accordance with an embodiment of the present invention. Figure 14 shows the experimental results of driving an LED having a rated current of 100 mA using two 1.5 V alkaline batteries using the technical features of the present invention. Comparing FIG. 14 with the prior art FIG. 7B, it can be seen that in the case where the LEDs maintain the same current (ie, the same luminance), the battery life using the prior art is only 100 minutes (as shown in FIG. 7B), and FIG. 14 shows the use of the present. The inventive electronic circuit can significantly extend battery life to 205 minutes. Referring to the results of this experiment, it can be clearly understood that the use of the present invention not only saves battery brightness but also extends battery life in the case where the same brightness is achieved.

FIG. 15 is a circuit diagram of a portable lighting device 1500 according to an embodiment of the invention. The driving circuit 1500 includes a battery power source 810, and is turned on. Off 820, light emitting element 830, sensing element 840, controller 1550, and inductor L1. 15 and FIG. 8 have the same or similar functions, and will not be described again for the sake of brevity.

In one embodiment, the controller 1550 includes a power input VIN coupled to the battery power source 810 via a switch 820. The sense terminal VSENSE of the controller 1550 is coupled to the battery power source 810 via a voltage divider 1502 and a switch 820. The power output terminal OUT is coupled to the light emitting element 830. The feedback terminal ISENSE is coupled to the sensing element 840. The ground terminal GND is coupled to the ground. The switching output terminal SW is coupled to the power input terminal VIN via the inductor L1. The indicator end BATLO is coupled to an indicator 1504. In one embodiment, the electronic circuit 1500 further includes a capacitor C1 coupled between the battery power source 810 and the power input terminal VIN of the controller 1550. In one embodiment, the portable lighting device 1500 further includes a capacitor C2 coupled between the light emitting component 830 and the power output OUT of the controller 1550.

In operation, if switch 830 is turned on, power input VIN receives power from battery power source 810, and sense terminal VSENSE receives sense signal SEN indicative of the voltage of battery power source 810. The power output terminal OUT provides output power to the light emitting element 830. The feedback terminal ISENSE receives the feedback signal FB indicating the current of the light-emitting element 830. The controller 1550 adjusts the current flowing through the light emitting element 830 according to the feedback signal FB and the sensing signal SEN. Specifically, if the sensing signal SEN indicating the voltage of the battery power source 810 is greater than the first voltage level, the controller 1550 adjusts the current of the light emitting element 830 to the first current level. If the sense signal SEN indicating the voltage of the battery power source 810 is less than the second voltage level, the controller 1550 adjusts the current of the light-emitting element 830 to the second current level. Wherein the second current level is lower than the first current level. If The sense signal SEN indicating the voltage of the battery power source 810 is between the first voltage level and the second voltage level, and the controller 1550 adjusts the current following the sense signal SEN flowing through the light-emitting element 830. Therefore, the controller 1550 can adjust the brightness of the light emitting element 830.

Figure 16 is a circuit diagram of the controller 1550 of Figure 15 containing internal functional blocks. 16 and FIG. 10A have the same or similar functions, and will not be described again for the sake of brevity. Figure 17 is a diagram showing the relationship between the reference signal ADJ and the sense signal SEN in Figure 16. Figure 16 will be described in conjunction with Figure 17.

In one embodiment, as shown in FIG. 16, the controller 1550 includes a low voltage lockout circuit 1651, a reference signal generation unit 1654, a dimming unit 1055, a driver 1056, a switch 1057, and a switch 1058. The low voltage locking circuit 1651 is coupled to the input terminal VIN. The reference signal generating unit 1654 is coupled to the sensing terminal VSENSE. The dimming unit 1055 is coupled to the reference signal generating unit 1654. The driver 1056 is coupled to the dimming unit 1055, and the switch 1057 and the switch 1058 are coupled to the driver 1056.

If switch 820 is turned on, input VIN receives power from battery power source 810. The reference signal generating unit 1654 generates a reference signal ADJ based on the sensing signal SEN. The reference signal ADJ indicates the target current level of the light-emitting element 830. The voltage V _{SEN of the} sense signal SEN is proportional to the voltage of the battery power source 810. When the voltage V _{SEN of the} sensing signal SEN is greater than the first level V _TH1 (ie, indicating that the voltage of the battery power source 810 is greater than the first voltage level), the voltage V _ADJ of the reference signal _ADJ is the first voltage level V _ADJ1 . When the voltage V _{SEN of the} sensing signal SEN is lower than the second level V _TH2 (ie, indicating that the voltage of the battery power source 810 is less than the second voltage level), the voltage V _ADJ of the reference signal _ADJ is the second voltage level V _ADJ2 . When the voltage V _{SEN of the} sensing signal SEN is higher than the second level V _TH2 but lower than the first level V _TH1 , the voltage V _{ADJ of the} reference signal ADJ changes with the voltage V _{SEN of the} sensing signal SEN, at this time, the light emitting element 830 The current also follows a linear change in the voltage of the battery power source 810.

The dimming unit 1055 generates a dimming signal DRV according to the reference signal ADJ and the feedback signal FB to adjust the current flowing through the light emitting element 830. In the embodiment shown in FIG. 16, switch 1057, switch 1058 and capacitor C2 and inductor L1 form a boost converter to boost the voltage at power supply output OUT to a voltage value sufficient to drive light-emitting element 830. The switching output terminal SW is coupled to the power input terminal VIN via the inductor L1 and is grounded via the switch 1057. The switching output terminal SW is also coupled to the power supply output OUT via the switch 1058. The power supply output OUT is also coupled to the capacitor C2. As such, even though the battery power source 810 provides a lower voltage (eg, a voltage of 1V), the controller 1550 can still drive the light emitting element 830 by boosting the voltage at the power supply output OUT via the boost converter. The driver 1056 controls the switch 1057 and the switch 1058 in accordance with the dimming signal DRV. In one embodiment, switch 1057 and switch 1058 operate in a complementary mode. In other words, switch 1057 and switch 1058 are alternately turned on and off. Therefore, the current of the light-emitting element 830 is adjusted to the target current level determined by the reference signal ADJ. Further, the reference signal generating unit 1654 also generates an indication signal IDC based on the sensing signal SEN. If the sense signal SEN indicates that the voltage of the battery power source 810 is lower than the second voltage level, the indication signal IDC is in the first state (eg, logic high). If the sense signal SEN indicates that the voltage of the battery power source 810 is greater than the second voltage level, the indicator signal IDC is in the second state (eg, logic low). Therefore, in one embodiment, if the indication signal IDC is in the first state, the indicator 1054 is turned on. To indicate that the voltage of the battery power source 810 is lower than the second voltage level. If the indication signal IDC is in the second state, the indicator 1054 is turned off to indicate that the voltage of the battery power source 810 is higher than the second voltage level. The low voltage lockout circuit 1651 turns off the controller 1550 when the voltage at the power supply input terminal VIN is below the cutoff threshold. The low voltage lockout circuit 1651 turns on the controller 1550 when the voltage at the power input terminal VIN is above the turn-on threshold.

FIG. 18 is a circuit diagram of the reference signal generating unit 1654 of FIG. The reference signal generating unit 1654 includes a first comparator 1808, a second comparator 1810, a first multiplexer 1804, a second multiplexer 1806, a sensing signal processing unit 1802, a third comparator 1812, and a switch 1858. The sensing signal processing unit 1802 provides the processed signal SEN' based on the sensing signal SEN. The processed signal SEN' is proportional to the sense signal SEN.

In operation, the first comparator 1808 compares the sensed signal SEN with the first threshold value _VTH1 to produce a first select signal SEL1. The second comparator 1810 compares the sense signal SEN with the second threshold value V _TH2 to generate a second select signal SEL2. The first multiplexer 1804 selectively outputs the processed signal SEN' or the first voltage signal ADJ1 according to the first selection signal SEL1. The second multiplexer 1806 selectively outputs the output signal of the first multiplexer 1804 or the second voltage signal ADJ2 according to the second selection signal SEL2. Specifically, if the voltage of the voltage V _SEN of the sensing signal SEN is greater than the first threshold value V _TH1 , the first multiplexer 1024 outputs the first voltage signal ADJ1 . The second multiplexer 1806 outputs an output signal of the first multiplexer 1804 (eg, the first voltage signal ADJ1) as a reference signal ADJ. If the voltage V _{SEN of the} sense signal SEN is lower than the second threshold value V _TH2 , the second multiplexer 1806 outputs the second voltage signal ADJ2 as a reference signal. If the voltage V _{SEN of the} sensing signal is greater than the second threshold V _TH2 but lower than the first threshold V _TH1 , the first multiplexer 1804 outputs the processed signal SEN ′, and the second multiplexer 1806 outputs the first The output signal of multiplexer 1804 (eg, processed signal SEN'). Thus, the voltage of the reference signal ADJ is proportional to the voltage of the sense signal SEN and, in turn, to the voltage of the battery power source 810.

If the voltage of the voltage V _SEN of the sense signal SEN is lower than the second threshold value V _TH2 , indicating that the voltage of the battery power source 810 is lower than the second voltage level, the third comparator 1812 turns off the switch 1858 to generate the first state. An indication signal (eg, logic high) to turn on indicator 1504. If the voltage V _{SEN of the} sense signal SEN is greater than the first threshold value V _TH1 , indicating that the voltage of the battery power source 810 is higher than the first voltage level, the third comparator 1812 turns on the switch 1858 to generate the second state (eg, logic) Low) indicator signal to turn off indicator 1504.

FIG. 19 is a circuit diagram of a portable lighting device 1900 according to an embodiment of the invention. The portable lighting device 1900 includes a battery power source 1110, a switch 820, a light emitting element 830, a sensing element 840, a controller 1950, an inductor L2, and a capacitor C2. 19 and FIG. 12 and FIG. 15 have the same or similar functions, and will not be described again for the sake of brevity.

Figure 20 is a schematic diagram of the controller 1950 of Figure 19 containing internal functional blocks. 20 has the same or similar functions as those of FIGS. 10 and 16. In one embodiment, controller 1950 includes a low voltage lockout circuit 1651, a reference signal generation unit 1654, a dimming unit 1055, a driver 1056, a switch 1357, and a switch 1358. The low voltage locking circuit 1651 is coupled to the power input terminal VIN. The reference signal generating unit 1654 is coupled to the sensing terminal VSENSE. Dimming unit 1055 and reference signal production The living unit 1654 is coupled. The driver 1056 is coupled to the dimming unit 1055. Switch 1357 and switch 1358 are coupled to driver 1056. In the embodiment shown in FIG. 20, the switch 1357, the switch 1358, and the capacitor C2 and the inductor L2 form a buck converter to reduce the voltage of the power supply output OUT of the controller 1950 to a lower level to still drive the light-emitting element 830. Voltage. In one embodiment, switch 1357 and switch 1358 operate in a complementary mode. In other words, the switch 1357 and the switch 1358 are alternately turned on and off. In the embodiment shown in FIG. 20, the switching output terminal SW is coupled to the power supply input terminal VIN via the switch 1357. The switching output terminal SW is grounded via a switch 1358. The switching output terminal SW is also grounded via the inductor L2 and the capacitor C2. Therefore, even if the battery power supply 1110 provides a voltage higher than a suitable voltage (eg, 6V) that drives the light-emitting element 830, the controller 1950 can drive the light-emitting element 830 at a lower voltage through the buck converter.

21 is a flow chart 2100 of a method of powering a light source in accordance with an embodiment of the present invention. In step 2102, the battery power supplies power to the light-emitting elements under the control of the controller. In step 2104, a sense signal indicative of the voltage of the battery power is provided to the controller. In step 2106, the current flowing through the light emitting element is adjusted according to the sensing signal. Specifically, when the sensing signal indicates that the voltage of the battery power source is greater than the first voltage level, the current flowing through the light emitting element is adjusted to the first current level; when the sensing signal indicates that the voltage of the battery power source is lower than the second voltage level On time, the current flowing through the illuminating element is adjusted to the second current level. The second voltage level is lower than the first voltage level. When the sensing signal indicates that the voltage of the battery power source is between the second voltage level and the first voltage level, the current flowing through the light emitting element is adjusted to a voltage change according to the sensing signal.

The method of powering the light source further includes the controller generating a reference signal based on the sensed signal. The reference signal indicates a target current level flowing through the light emitting element. When the sensing signal indicates that the voltage of the battery power source is greater than the first voltage level, the voltage of the reference signal is at the first voltage level; when the sensing signal indicates that the voltage of the battery power source is lower than the second voltage level, the voltage of the reference signal is at the The second voltage level; when the sensing signal indicates that the voltage of the battery power source is between the second voltage level and the first voltage level, the voltage of the reference signal follows the sensing signal to linearly change.

The method of powering the light source further includes the controller generating an indication signal based on the sensing signal to control the indicator. The sensing signal indicates that the voltage of the battery power source is lower than the second voltage level, the indication signal is in the first state; and when the sensing signal indicates that the voltage of the battery power source is greater than the second voltage level, the indication signal is in the second state.

Advantageously, the present invention provides circuitry for powering a light source. The controller senses the voltage of the battery power source and adjusts the reference signal according to the voltage of the battery. The current flowing through the light emitting element is adjusted according to a reference signal indicating a target current value of the light emitting element. If the voltage of the battery power supply is low, the current flowing through the light-emitting element is adjusted to a lower level. Therefore, the life of the battery is extended, thereby extending the life of the light-emitting element.

It will be understood by one of ordinary skill in the art that the "battery" herein is not limited to a dry battery or an alkaline battery, and may include a lithium battery or other type of battery. Further, although the embodiment of the present invention shows only one light-emitting element, it is understood that the present invention is not limited to the number of light-emitting elements, but any number of light-emitting elements may be employed. Here, for convenience of description, a light-emitting diode (LED) is taken as an embodiment, but the invention is not limited thereto, and the LED can be used. Replace with other types of light-emitting elements. Although the invention is described by taking a flashlight as an example, it is not limited to a household or small flashlight, and it also includes a portable lighting device of different sizes and different uses. For example, but not limited to: mountaineering, headlights used for detection, or bicycle lights, etc.

The above detailed description and the accompanying drawings are only typical embodiments of the invention. It is apparent that various additions, modifications and substitutions are possible without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood by those skilled in the art that the present invention may be changed in form, structure, arrangement, ratio, material, element, element, and other aspects without departing from the scope of the invention. The presently disclosed embodiments are, however, to be construed as limited by the description

100‧‧‧Power system

102‧‧‧Adapter

103‧‧‧ switch

104‧‧‧DC/DC converter

105‧‧‧ switch

106‧‧‧Charger

108‧‧‧Lighting diode

110‧‧‧Battery

200‧‧‧Power System

202‧‧‧Adapter

203‧‧‧Switch

205‧‧‧ switch

206‧‧‧ Controller

207‧‧‧ switch

208‧‧‧Lighting diode

210‧‧‧Battery

211‧‧‧ Capacitance

212‧‧‧Induction resistance

213‧‧‧ Capacitance

214‧‧‧Inductance

216‧‧‧Induction resistance

220‧‧‧Control circuit

230‧‧‧voltage resistor

411‧‧‧Oscillator

412‧‧‧Factor

413‧‧‧ comparator

414‧‧‧Selector

415, 416‧‧‧ error amplifier

417‧‧‧ comparator

419‧‧‧Error amplifier

421, 422‧‧‧ and gate

431‧‧‧Adder

432‧‧‧Amplifier

433‧‧‧Ramp signal generator

434, 436‧‧ ‧ subtractor

440‧‧‧Voltage regulator

446‧‧‧voltage source

600‧‧‧ Flowchart

602, 603, 604, 605, 606‧‧ steps

700‧‧‧ circuits

710‧‧‧Battery Pack

720‧‧‧ switch

730‧‧‧Light source

740‧‧‧ Current limiting resistor

750‧‧‧ performance chart

800‧‧‧ portable lighting device

810‧‧‧Battery power supply

820‧‧‧ switch

830‧‧‧Lighting elements

840‧‧‧Sensor components

850‧‧‧ Controller

900‧‧‧Portable lighting

950‧‧‧ Controller

1051‧‧‧Low voltage lockout circuit

1052‧‧‧Trigger circuit

1053‧‧‧ Clock Generator

1054‧‧‧Reference selector

1055‧‧‧ dimming unit

1056‧‧‧ drive

1057, 1058‧‧ ‧ switch

1100‧‧‧ portable lighting

1110‧‧‧Battery power supply

1150‧‧‧ Controller

1200‧‧‧ portable lighting device

1250‧‧‧ Controller

1357, 1358‧‧ ‧ switch

1500‧‧‧ portable lighting device

1502‧‧  voltage divider

1504‧‧‧ indicator

1651‧‧‧Low voltage lockout circuit

1654‧‧‧Reference signal generating unit

1802‧‧‧Sensor signal processing unit

1804‧‧‧First multiplexer

1806‧‧‧Second multiplexer

1808‧‧‧First comparator

1810‧‧‧Second comparator

1812‧‧‧ third comparator

1858‧‧‧Switch

1900‧‧‧ portable lighting device

1950‧‧‧ Controller

2100‧‧‧Flowchart

2102, 2104, 2106‧‧‧ steps

The technical method of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments to make the features and advantages of the present invention more obvious. Among them: Figure 1 shows a block diagram of a conventional power system.

2 is a block diagram of a power supply system in accordance with an embodiment of the present invention.

A schematic diagram of the relationship between the adjustable reference voltage V _ADJ and the voltage V _UVLS in the power supply system shown in FIG. 2 is shown in FIG. 2A.

Figure 3A shows an exemplary timing diagram of the output control signals of the outputs 埠CTR1, CTR2 and CTR3 of the controller in the charging mode.

Figure 3B shows an exemplary timing diagram of the output control signals of the controller outputs CTR1, CTR2, and CTR3 in the load supply mode.

4 is a block diagram showing the structure of the control circuit shown in FIG. 2 according to an embodiment of the present invention.

FIG. 5 is a timing diagram of signals associated with the flip-flop of FIG. 4, in accordance with an embodiment of the present invention.

6 is a flow chart showing the operation of a power supply system in accordance with an embodiment of the present invention.

Figure 7A shows a schematic circuit diagram of a conventional flashlight.

Figure 7B is a graph showing the performance of the circuit of Figure 7A.

FIG. 8 is a circuit diagram of a portable lighting device according to an embodiment of the invention.

FIG. 9 is a circuit diagram of a portable lighting device according to another embodiment of the present invention.

Figure 10A is a circuit diagram of the controller shown in Figure 9.

Fig. 10B is a timing chart showing the dimming control of the controller shown in Fig. 10A.

FIG. 11 is a circuit diagram of a portable lighting device according to still another embodiment of the present invention.

FIG. 12 is a circuit diagram of a portable lighting device according to still another embodiment of the present invention.

Figure 13 is a circuit diagram of the controller of Figure 12.

Figure 14 is a graph showing the performance of the portable lighting device shown in Figure 10A in accordance with an embodiment of the present invention.

FIG. 15 is a circuit diagram of a portable lighting device according to an embodiment of the invention.

Figure 16 shows the controller of Figure 15 containing the internal functional blocks. Road map.

Figure 17 is a diagram showing the relationship between the reference signal ADJ and the sense signal SEN shown in Figure 16.

Fig. 18 is a circuit diagram showing the reference signal generating unit of Fig. 16.

FIG. 19 is a circuit diagram of a portable lighting device according to an embodiment of the invention.

Figure 20 is a schematic diagram of the controller of Figure 19 containing internal functional blocks.

21 is a flow chart of a method of powering a light source in accordance with an embodiment of the present invention.

800‧‧‧ portable lighting device

810‧‧‧Battery power supply

820‧‧‧ switch

830‧‧‧Lighting elements

840‧‧‧Sensor components

850‧‧‧ Controller

Claims (16)

A portable lighting device comprising: a power source providing a voltage; a load circuit comprising a light emitting diode light source; and a controller receiving the voltage and regulating the flow according to a sensing signal indicating the voltage a current of the light emitting diode light source, wherein when the sensing signal indicating the voltage is higher than a first voltage level, the controller adjusts the current flowing through the light emitting diode light source to a first a current level, and wherein, when the sensing signal indicating the voltage is lower than a second voltage level, the controller adjusts the current flowing through the light emitting diode source to a second current level, and wherein When the sensing signal indicating the voltage is between the first voltage level and the second voltage level, the controller adjusts the current flowing through the light emitting diode source to follow the sensing signal change, The controller includes a reference signal generating unit, and generates a reference signal according to the sensing signal, wherein when the sensing signal indicating the voltage is greater than the first voltage level, a voltage of the reference signal is at a first voltage level, and wherein when the sensing signal indicating the voltage is lower than the second voltage level, the voltage of the reference signal is at the second voltage level; when the sensing signal indicating the voltage When the voltage level is between the first voltage level and the second voltage level, the voltage of the reference signal changes linearly following the sensing signal, wherein the reference signal generating unit comprises: a first comparator, the sense The measured signal is compared with a first threshold value; a second comparator, comparing the sensing signal with a second threshold; a sensing signal processing unit, providing a processed signal according to the sensing signal; a first multiplexer, according to the first An output of the comparator selectively outputs the processed signal or a first voltage signal; and a second multiplexer selectively outputs an output of the first multiplexer according to an output of the second comparator A signal or a second voltage signal. The portable lighting device of claim 1, wherein the controller according to the sensing when the sensing signal indicating the voltage is between the first voltage level and the second voltage level The signal and a feedback signal regulate the current flowing through the light emitting diode source to follow a linear change in the voltage, wherein the feedback signal indicates the current flowing through the light emitting diode source. The portable lighting device of claim 1, wherein the processed signal is proportional to the sensing signal. The portable lighting device of claim 1, wherein the controller comprises a dimming unit, and generates a dimming signal according to the reference signal and a feedback signal to adjust the light source flowing through the LED The current, wherein the feedback signal indicates the current flowing through the light emitting diode source. The portable lighting device of claim 1, wherein the controller generates an indication signal according to the sensing signal, wherein when the sensing signal indicating the voltage is lower than the second voltage level, The indication signal is in a first state; when the sensing signal indicating the voltage is When the second voltage level is higher than the second voltage level, the indication signal is in a second state. The portable lighting device of claim 5, wherein the portable lighting device further comprises an indicator, wherein the indicator is turned on when the indication signal is in the first state; when the indication The indicator is turned off when the signal is in the second state. The portable lighting device of claim 1, wherein the controller comprises a sensing end coupled to the power source and receiving the sensing signal indicating the voltage. The portable lighting device of claim 1, wherein the controller includes a power input terminal for receiving the voltage. The portable lighting device of claim 8, wherein the controller comprises a switching output coupled to the power input through an inductor. A method for supplying power to a light emitting diode light source, comprising: a power supply to a light emitting diode light source under control of a controller; the controller receiving a sensing signal indicating a voltage of the power source; When the sensing signal of the voltage of the power source is higher than a first voltage level, the controller adjusts a current flowing through the light emitting diode light source to a first current level; when the voltage of the power source is indicated When the sensing signal is lower than a second voltage level, the controller adjusts the current flowing through the light emitting diode source to a second current level; and the sensing when the voltage of the power source is indicated Signal at the first voltage When the level is between the level and the second voltage level, the controller adjusts the current flowing through the light emitting diode source to follow the sensing signal change, wherein the controller includes a reference signal generating unit, according to the sense The measurement signal generates a reference signal, wherein when the sensing signal indicating the voltage is greater than the first voltage level, a voltage of the reference signal is at the first voltage level, and wherein the sense of the voltage is indicated When the measured signal is lower than the second voltage level, the voltage of the reference signal is at the second voltage level; when the sensing signal indicating the voltage is between the first voltage level and the second voltage level The voltage of the reference signal changes linearly following the sensing signal, wherein the reference signal generating unit comprises: a first comparator, comparing the sensing signal with a first threshold; and a second comparison Comparing the sensing signal with a second threshold value; a sensing signal processing unit providing a processed signal according to the sensing signal; a first multiplexer according to the first comparator Output selection And outputting the processed signal or a first voltage signal; and a second multiplexer selectively outputting an output signal or a second voltage of the first multiplexer according to an output of the second comparator signal. The method of claim 10, wherein when the sensing signal indicating the voltage of the power source is between the first voltage level and the second voltage level, according to the sensing signal and a Signaling the current flowing through the light emitting diode source to follow the voltage change The feedback signal indicates the current flowing through the light emitting diode source. The method of claim 10, further comprising: the controller generating an indication signal according to the sensing signal, controlling an indicator; when the sensing signal indicating the voltage of the power source is lower than the second voltage level Controlling the indication signal in a first state on time; and controlling the indication signal to be in a second state when the sensing signal indicating the voltage of the power source is higher than the second voltage level. A controller for controlling power supply to a light emitting diode light source includes: a power input end coupled to a power source for receiving a voltage from the power source; and a sensing end coupled to the power source to receive the power source a sensing signal of the voltage; and a feedback end receiving a feedback signal indicating a current flowing through the light emitting diode light source, wherein the controller generates an indication flow according to the feedback signal and the sensing signal Passing a reference signal of a target current of the light emitting diode light source, and adjusting the current flowing through the light emitting diode light source according to the feedback signal and the reference signal, when the sensing of the voltage of the power source is indicated When the signal is higher than a first voltage level, a voltage of the reference signal is at the first voltage level; when the sensing signal indicating the voltage of the power source is lower than a second voltage level, the reference signal The voltage is at the second voltage level; when the sensing signal indicating the voltage of the power source is between the first voltage level and the second voltage level The voltage of the reference signal follows a linear change of the sense signal, wherein the controller further comprises: a first comparator, comparing the sensed signal with a first threshold signal; and a second comparison Comparing the sensing signal with a second threshold signal; a sensing signal processing unit providing a processed signal according to the sensing signal; a first multiplexer according to the first comparator An output selectively outputting the processed signal or a first voltage signal; and a second multiplexer selectively outputting an output signal or a first multiplexer of the first multiplexer according to an output of the second comparator Two voltage signals. The controller of claim 13, wherein the processed signal is proportional to the sensed signal. The controller of claim 13, wherein the controller generates an indication signal according to the sensing signal, wherein when the sensing signal indicating the voltage of the power source is lower than the second voltage level, The indication signal is in a first state; when the sensing signal indicating the voltage of the power source is higher than the second voltage level, the indication signal is in a second state. The controller of claim 13 further comprising an indication end coupled to an indicator, wherein when the sensing signal indicating the voltage of the power source is lower than the second voltage level, the indicator is Turning on; the indicator is turned off when the sensed signal indicating the voltage of the power source is higher than the second voltage level.