TWI381625B - Circuits and controllers for driving light source - Google Patents

Description

Light source driving circuit and controller

The invention relates to a driving circuit, in particular to a light source driving circuit and a controller.

FIG. 1 is a schematic diagram of a conventional light source driving circuit 100. The light source driving circuit 100 is for driving a light source (for example, the light emitting diode string 108). The light source driving circuit 100 supplies an input voltage VIN from a power source 102 to power the driving circuit 100. The light source driving circuit 100 includes a buck converter that provides an adjusted voltage VOUT to the LED string 108 under the control of a controller 104. The buck converter includes a diode 114, an inductor 112, a capacitor 116, and a switch 106. A resistor 110 is coupled in series with the switch 106. When the switch 106 is turned on, the resistor 110 is coupled to the inductor 112 and the LED string 108, and generates a feedback signal to indicate the current flowing through the inductor 112. When the switch 106 is turned off, the resistor 110 is disconnected from the inductor 112 and the LED string 108, so no current flows through the resistor 110.

Switch 106 is controlled by controller 104. When the switch 106 is turned on, a current flows through the LED string 108, the inductor 112, the switch 106, and the resistor 110 to ground. This current gradually increases under the action of the inductor 112. When the current increases to a predetermined peak current level, the controller 104 turns off the switch 106. When the switch 106 is turned off, a current flows through the LED string 108, the inductor 112, and the diode 114. The controller 104 can turn the switch 106 on again after a period of time. Therefore, the controller 104 controls based on the preset peak current level Buck converter. However, the average current level flowing through the inductor 112 and the LED string 108 varies with the inductance of the inductor 112, the input voltage VIN, and the voltage VOUT across the LED string 108, thus flowing through the inductor 112. The average current level (i.e., the average current flowing through the LED string 108) cannot be accurately controlled.

In order to solve the above technical problem, the present invention provides a light source driving circuit, comprising: a first inductor coupled in series to a light source for supplying power to the light source; and a controller electrically coupled to a switch coupled to the switch To the first inductor, the controller controls a current flowing through the first inductor; a current sensor coupled to the first inductor and providing a first indicating the current flowing through the first inductor a second inductor is electromagnetically coupled to the first inductor to sense a power condition of the first inductor, and the first inductor and the second inductor are electrically coupled to the switch and the first inductor a common node, wherein the common node provides a reference ground for the controller, and the reference ground is different from the ground of the light source driving circuit; a filter coupled to the current sensor to provide an indication flow a second signal passing through the average current of the first inductor; and an error amplifier generating an error signal based on the second signal and a reference signal indicating a target current level; wherein the error amplifier generates the error signal A difference signal to adjust the current flowing through the current source to the target level.

A controller for controlling power transmitted to a light source, comprising: a first inductive pin sensing an instantaneous current flowing through an energy storage component; and a second inductive pin sensing an average flowing through the energy storage component Current; a third sense Should be connected to the pin to detect whether the instantaneous current is reduced to a predetermined current level; a driving pin provides a driving signal to control the switch coupled with the driving pin, thereby controlling an average current flowing through the light source to be equal to a target a current level, wherein the driving signal is generated based on signals received by the first sensing pin, the second sensing pin, and the third sensing pin, and an error amplifier based on the target current value and A second inductive pin, the monitoring signal indicating the average current flowing through the energy storage element generates an error signal, wherein the driving signal is further generated according to the error signal.

A detailed description of the embodiments of the present invention will be given below. While the invention will be described in conjunction with the embodiments, it is understood that the invention is not limited to the 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.

The present invention provides a circuit that controls a power converter to power various loads (e.g., light sources). The circuit can include a current sensor for monitoring energy storage elements (eg, an inductor), and a controller including a switch that can be coupled to the inductor to control the average power of the source The flow is a target current value. The current sensor monitors the current flowing through the inductor regardless of whether the switch is on or off.

2 is a schematic diagram of a drive circuit 200 in accordance with an embodiment of the present invention. Light source drive circuit 200 includes a rectifier 204 that receives an input voltage from a power source 202 and provides an adjusted voltage to power converter 206. Power converter 206 receives the adjusted voltage and provides an output power to load 288. In an embodiment, power converter 206 can be a buck converter or a boost converter. In one embodiment, power converter 206 includes an energy storage component 214 and a current sensor 278 (eg, a resistor) for sensing the power condition of energy storage component 214. Current sensor 278 provides a first signal ISEN to controller 210 to indicate the instantaneous current flowing through energy storage element 214. The drive circuit 200 also includes a filter 212 that generates a second signal IAVG for indicating an average current flowing through the energy storage element 214 based on the first signal ISEN. In one embodiment, the controller 210 receives the first signal ISEN and the second signal IAVG and controls the average current flowing through the energy storage element 214 to be a target current value level.

FIG. 3 is a circuit diagram of a light source driving circuit 300 according to an embodiment of the invention. Elements in Figure 3 having the same reference numerals as in Figure 2 have similar functions. In the example of FIG. 3, the light source driving circuit 300 includes a rectifier 204, a power converter 206, a filter 212, and a controller 210. Rectifier 204 can be a bridge rectifier including diodes D1-D4. Rectifier 204 adjusts the voltage from power source 202. Power converter 206 receives the voltage adjusted by rectifier 204 and provides an output power to power the load (e.g., LED string 208).

In the example of FIG. 3, the power converter 206 is a buck converter. The device includes a capacitor 308, a switch 316, a diode 314, a current inductor (eg, resistor 218), an inductor 302 and an inductor 304 coupled to each other, and a capacitor 324. The diode 314 is coupled between the switch 316 and the ground of the light source driving circuit 300. The capacitor 324 is coupled in parallel with the LED string 208. In an embodiment, the inductor 302 and the inductor 304 are electromagnetically coupled to each other. More specifically, the inductor 302 and the inductor 304 are coupled to a common node 333. In the example of FIG. 3, the common node 333 is interposed between the resistor 218 and the inductor 302. However, the invention is not limited to this architecture, and the common node 333 can also be located between the switch 316 and the resistor 218. The common node 333 provides a reference ground for the controller 210. In an embodiment, the reference ground of the controller 210 is different from the ground of the light source driving circuit 300. By turning on and off switch 316, the current flowing through inductor 302 can be adjusted to adjust the power supplied to light emitting diode string 208. Inductor 304 senses the power condition of inductor 302, for example, monitoring whether the current flowing through inductor 302 drops to a predetermined current level.

One end of the resistor 218 is coupled to a node between the switch 316 and the cathode of the diode 314, and the other end of the resistor 218 is coupled to the inductor 302. When switch 316 is turned "on" and "off", resistor 218 provides a first signal ISEN indicative of the instantaneous current flowing through inductor 302. In other words, the resistor 218 senses the instantaneous current flowing through the inductor 302 regardless of whether the switch 316 is turned "on" or "off". Filter 212 is coupled to resistor 218 and produces a second signal IAVG indicative of the average current flowing through inductor 302. In an embodiment, filter 212 includes a resistor 320 and a capacitor 322.

The controller 210 receives the first signal ISEN and the second signal IAVG and controls the average current flowing through the inductor 302 to be a target current level by turning on or off the switch 316. Capacitor 324 filters out light emitting diode strings 208 The chopping current, in turn, causes the current flowing through the LED string 208 to be smooth and substantially equal to the average current flowing through the inductor 302. Thus, the current flowing through the LED string 208 can be substantially equal to the target current. Here, "substantially equal to the target current" means that the current flowing through the LED string 208 may be slightly different from the target current, but is still within an allowable range, so that the circuit component is not considered to be undesirable. The power transmitted from the inductor 304 to the controller 210 can be ignored and can be ignored.

In the example of FIG. 3, the endpoints of controller 210 include ZCD, GND, DRV, VDD, CS, COMP, and FB. The terminal ZCD is coupled to the inductor 304 for receiving a detection signal AUX indicating the power condition of the inductor 302 (eg, whether the current flowing through the inductor 302 is reduced to a preset current level, for example, “0”). The detection signal AUX can also indicate whether the LED string 208 is in an open state. The endpoint DRV is coupled to the switch 316 and generates a drive signal (eg, a pulse width modulation signal PWM1) to turn the switch 316 on or off. Endpoint VDD is coupled to inductor 304 and receives power from inductor 304. The terminal CS is coupled to the resistor 218 and receives a first signal ISEN indicative of an instantaneous current flowing through the inductor 302. The terminal COMP is coupled to the reference ground of the controller 210 via a capacitor 318. The terminal FB is coupled to the resistor 218 through the filter 212 to receive a second signal IAVG indicative of the average current flowing through the inductor 302. In the example of FIG. 3, the terminal GND (ie, the reference ground of the controller 210) is coupled to a common node 333 between the resistor 218, the inductor 302, and the inductor 304.

Switch 316 can be an N-channel metal oxide semiconductor field effect transistor (NMOSFET). The conduction state of the switch 316 is based on the gate voltage of the switch 316 and the voltage at the terminal GND (ie, the voltage at the common node 333). A voltage difference between them is determined. Therefore, the pulse width modulation signal PWM1 output from the terminal DRV determines the on or off state of the switch 316. When the switch 316 is turned on, the voltage level of the reference ground of the controller 210 is higher than the voltage level of the ground of the light source driving circuit 300, and thus the circuit of the present invention can be applied to a power source having a relatively high voltage.

In operation, when switch 316 is turned on, a current flows through switch 316, resistor 218, inductor 302, and LED string 208 to ground of light source drive circuit 300. When switch 316 is open, a current flows through resistor 218, inductor 302, LED string 208, and diode 314. The inductor 304 is magnetically coupled to the inductor 302 to detect the power condition of the inductor 302, for example, to detect if the current flowing through the inductor 302 has decreased to a preset current level. Therefore, the controller 210 monitors the current flowing through the inductor 302 through the detection signal AUX, the first signal ISEN, and the second signal IAVG, and controls the switch 316 through the pulse width modulation signal PWM1 to control the average current flowing through the inductor 302. A target current level. Therefore, the current flowing through the LED string 208 after being filtered by the capacitor 324 can also be substantially equal to the target current level.

In an embodiment, the controller 210 determines whether the LED string 208 is in an open state based on the detection signal AUX. If the LED string 208 is open, the voltage across the capacitor 324 increases. When the switch 316 is in the off state, the voltage across the inductor 302 increases, and the voltage of the detection signal AUX also increases accordingly. As a result, the current flowing into the controller 210 through the terminal ZCD increases. Accordingly, the controller 210 monitors the detection signal AUX, and if the switch 316 is turned off and the current flowing into the controller 210 increases beyond a current threshold, the controller 210 determines that the LED string 208 is in an open state.

The controller 210 can also determine whether the light emitting diode string 208 is in a short circuit state based on the voltage at the terminal VDD. If the LED string 208 is short-circuited, when the switch 316 is in the off state, since both ends of the inductor 302 are coupled to the ground of the light source driving circuit 300, the voltage across the inductor 302 will decrease. The voltage across inductor 304 and the voltage at terminal VDD are also reduced accordingly. Therefore, when the switch 316 is in the off state, if the voltage at the terminal VDD is lower than a voltage threshold, the controller 210 determines that the LED string 208 is in a short circuit state.

4 is a schematic diagram of the controller 210 shown in FIG. 3 in accordance with an embodiment of the present invention. FIG. 5 is a waveform diagram of the controller 210 shown in FIG. 4 in accordance with an embodiment of the present invention. Figure 4 will be described in conjunction with Figures 3 and 5.

In the example of FIG. 4, controller 210 includes an error amplifier 402, a comparator 404, and a pulse width modulation signal generator 408. The error amplifier 402 generates an error signal VEA based on a voltage difference between a reference signal SET and a second signal IAVG. The reference signal SET can indicate the target current level. The second signal IAVG is received through the terminal FB to indicate the average current flowing through the inductor 302. The error signal VEA can be used to adjust the average current flowing through the inductor 302 to the target current level. The comparator 404 is coupled to the error amplifier 402 and compares the error signal VEA with the first signal ISEN. The first signal ISEN is received through the terminal CS indicating the instantaneous current flowing through the inductor 302. The sense signal AUX is received through the endpoint ZCD indicating whether the current flowing through the inductor 302 has dropped to a predetermined current level (eg, reduced to zero). The pulse width modulation signal generator 408 is coupled to the comparator 404 and the terminal ZCD, and generates a pulse width modulation based on the output of the comparator 404 and the detection signal AUX. Change signal PWM1. The pulse width modulation signal PWM1 controls the conduction state of the switch 316 through the terminal DRV.

The pulse width modulation signal generator 408 generates a pulse width modulation signal PWM1 having a first level (eg, logic 1) to turn on the switch 316. When the switch 316 is turned on, a current flows through the switch 316, the resistor 218, the inductor 302, and the LED string 208 to the ground of the light source driving circuit 300. The current flowing through the inductor 302 gradually increases, so that the voltage of the first signal ISEN gradually increases. In an embodiment, when the switch 316 is turned on, the voltage of the detection signal AUX is a negative value. In one embodiment, within controller 210, comparator 404 compares error signal VEA with first signal ISEN. When the voltage of the first signal ISEN exceeds the voltage of the error signal VEA, the comparator 404 outputs a logic 0, otherwise the comparator 404 outputs a logic 1. In other words, the output of comparator 404 is a series of pulses. The pulse width modulation signal generator 408 generates a pulse width modulation signal PWM1 having a second level (e.g., logic 0) in response to the negative going output of the comparator 404, thereby turning off the switch 316. When the switch 316 is turned off, the voltage of the detection signal AUX becomes a positive value. When switch 316 is open, a current flows through resistor 218, inductor 302, LED string 208, and diode 314. The current flowing through the inductor 302 gradually decreases, so the voltage of the first signal ISEN gradually decreases. When the current flowing through the inductor 302 is reduced to a predetermined current level (eg, reduced to zero), the voltage of the detection signal AUX will generate a negative edge, and the pulse width modulation signal generator 408 will have the first state ( For example, the pulse width modulation signal PWM1 of logic 1) turns on the switch 316.

In one embodiment, the duty cycle ratio of the pulse width modulation signal PWM1 is determined by the error signal VEA. If the voltage of the second signal IAVG is small At the voltage of the reference signal SET, the error amplifier 402 increases the voltage of the error signal VEA to increase the duty cycle ratio of the pulse width modulation signal PWM1. Accordingly, the average current flowing through the inductor 302 increases until the voltage of the second signal IAVG increases to the voltage level of the reference signal SET. If the voltage of the second signal IAVG is greater than the voltage of the reference signal SET, the error amplifier 402 reduces the voltage of the error signal VEA to reduce the duty cycle ratio of the pulse width modulation signal PWM1, thereby reducing the average current flowing through the inductor 302 until The voltage of the second signal IAVG is lowered to the voltage level of the reference signal SET. Therefore, the average current flowing through the inductor 302 can be maintained to be equal to the target current level.

FIG. 6 is a block diagram showing another architecture of the controller 210 shown in FIG. 3 according to an embodiment of the invention. FIG. 7 is a waveform diagram of the controller 210 shown in FIG. 6 in accordance with an embodiment of the present invention. Figure 6 will be described in conjunction with Figures 3 and 7.

In the example of FIG. 6, the controller 210 includes an error amplifier 602, a comparator 604, a sawtooth signal generator 606, a reset signal generator 608, and a pulse width modulation signal generator 610. The error amplifier 602 generates an error signal VEA based on a voltage difference between a reference signal SET and a second signal IAVG. The reference signal SET indicates a target current level. The second signal IAVG receives an average current indicative of the flow through the inductor 302 through the terminal EB. The error signal VEA can be used to adjust the average current flowing through the inductor 302 to be equal to the target current level. The sawtooth signal generator 606 generates a sawtooth signal SAW. The comparator 604 is coupled to the error amplifier 602 and the sawtooth signal generator 606 and compares the error signal VEA with the sawtooth signal SAW. The reset signal generator 608 generates a reset signal RESET and provides The reset signal RESET is applied to the sawtooth signal generator 606 and the pulse width modulation signal generator 610. In response to the reset signal RESET, the switch 316 is turned "on". The pulse width modulation signal generator 610 is coupled to the comparator 604 and the reset signal generator 608, and generates a pulse width modulation signal PWM1 based on the output of the comparator 604 and the reset signal RESET. The pulse width modulation signal PWM1 controls the conduction state of the switch 316 through the terminal DRV.

In one embodiment, the reset signal RESET is a pulse signal having a fixed frequency. In another embodiment, the reset signal RESET is a pulse signal that causes the switch 316 to be in an off state for a constant period of time. The reset signal RESET is such that the time when the pulse width modulation signal PWM1 in FIG. 5 is logic 0 is a constant.

In operation, pulse width modulation signal generator 610 generates a pulse width modulation signal PWM1 having a first state (eg, logic 1) to turn on switch 316 and to respond to reset signal RESET. When the switch 316 is turned on, a current flows through the switch 316, the resistor 218, the inductor 302, and the LED string 208 to the ground of the light source driving circuit 300. The voltage of the sawtooth wave signal SAW generated by the sawtooth signal generator 606 is increased from an initial level INI in response to the pulse of the reset signal RESET. When the voltage of the sawtooth signal SAW increases to the voltage of the error signal VEA, the pulse width modulation signal generator 610 generates a pulse width modulation signal PWM1 having a second state (eg, logic 0) to turn off the switch 316, and The voltage of the sawtooth signal SAW is reset to the initial level INI until the sawtooth signal generator 606 receives the next pulse of the reset signal RESET. Upon receiving the next pulse of the reset signal RESET, the voltage of the sawtooth signal SAW will gradually increase from the initial level INI again in response to the pulse.

In one embodiment, the duty cycle ratio of the pulse width modulation signal PWM1 is determined by the error signal VEA. If the voltage of the second signal IAVG is less than the voltage of the reference signal SET, the error amplifier 602 increases the voltage of the error signal VEA to increase the duty cycle ratio of the pulse width modulation signal PWM1. Accordingly, the average current flowing through the inductor 302 increases until the voltage of the second signal IAVG increases to the voltage level of the reference signal SET. If the voltage of the second signal IAVG is greater than the voltage level of the reference signal SET, the error amplifier 602 reduces the voltage of the error signal VEA to reduce the duty cycle ratio of the pulse width modulation signal PWM1. Accordingly, the average current flowing through the inductor 302 decreases until the voltage of the second signal IAVG drops to the voltage level of the reference signal SET. Therefore, the average current flowing through the inductor 302 can be maintained to be equal to the target current level.

FIG. 8 is a schematic diagram of a light source driving circuit light source driving circuit 800 according to another embodiment of the present invention. Elements in Figure 8 having the same reference numerals as in Figures 2 and 3 have similar functions.

The terminal VDD of the controller 210 is coupled to the rectifier 204 through the switch 804 and receives the output voltage adjusted by the rectifier 204. A Zener diode 802 coupled between the switch 804 and the reference ground of the controller 210 is used to maintain the voltage at the terminal VDD substantially constant. In the example of FIG. 8 , the terminal ZCD of the controller 210 is electrically coupled to the inductor 302 and receives a detection signal AUX indicating the power condition of the inductor 302 . The detection signal AUX may indicate whether the current flowing through the inductor 302 has decreased to a preset current level (eg, whether it is reduced to zero). The common node 333 can provide a reference ground for the controller 210.

In summary, the present invention provides a control power converter to be negative A circuit that carries power. In one embodiment, the power converter provides a substantially constant current to a load, such as a string of light emitting diodes. In another embodiment, the power converter provides a current to charge the battery. The current provided by the circuit of the present invention to the load or battery can be more accurately controlled than the conventional circuit of FIG. Moreover, the circuit of the present invention is applicable to voltage sources having relatively high voltages.

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 of ordinary skill in the art that the present invention may be applied in the form of the form, structure, arrangement, ratio, material, element, element, and other aspects in the actual application without departing from the invention. Changed. Therefore, the embodiments disclosed herein are intended to be illustrative and not limiting, and the scope of the invention is defined by the scope of the appended claims and their legal equivalents.

100‧‧‧Light source drive circuit

102‧‧‧Power supply

104‧‧‧ Controller

106‧‧‧Switch

108‧‧‧Lighting diode strings

110‧‧‧resistance

112‧‧‧Inductance

114‧‧‧dipole

116‧‧‧ Capacitance

200‧‧‧ drive circuit

202‧‧‧Power supply

204‧‧‧Rectifier

206‧‧‧Power Converter

208‧‧‧Lighting diode strings

210‧‧‧ Controller

212‧‧‧ filter

214‧‧‧ Energy storage components

218‧‧‧resistance

278‧‧‧ Current sensor

288‧‧‧load

300‧‧‧Light source drive circuit

302, 304‧‧‧Inductance

308‧‧‧ Capacitance

314‧‧‧ diode

316‧‧‧ switch

318‧‧‧ Capacitance

320‧‧‧resistance

322‧‧‧ Capacitance

324‧‧‧ Capacitance

333‧‧‧Common node

402‧‧‧Error amplifier

404‧‧‧ Comparator

408‧‧‧Pulse width modulation signal generator

602‧‧‧Error amplifier

604‧‧‧ Comparator

606‧‧‧Sawtooth signal generator

608‧‧‧Reset signal generator

610‧‧‧Pulse width modulation signal generator

800‧‧‧Light source drive circuit

802‧‧ ‧ Zener diode

804‧‧‧ switch

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. Wherein: Figure 1 shows a schematic diagram of a conventional light source driving circuit.

2 is a schematic diagram of a driving circuit in accordance with an embodiment of the present invention.

3 is a circuit diagram of a light source driving circuit according to an embodiment of the invention.

4 is a schematic diagram of the controller shown in FIG. 3 in accordance with an embodiment of the present invention.

Figure 5 is a waveform diagram of the controller shown in Figure 4 in accordance with an embodiment of the present invention.

FIG. 6 is a block diagram showing another architecture of the controller shown in FIG. 3 according to an embodiment of the invention.

Figure 7 is a waveform diagram of the controller shown in Figure 6 in accordance with an embodiment of the present invention.

FIG. 8 is a schematic diagram of a light source driving circuit light source driving circuit according to another embodiment of the present invention.

200‧‧‧ drive circuit

202‧‧‧Power supply

204‧‧‧Rectifier

206‧‧‧Power Converter

210‧‧‧ Controller

212‧‧‧ filter

214‧‧‧ Energy storage components

278‧‧‧ Current sensor

288‧‧‧load

Claims (15)

A light source driving circuit includes: a first inductor coupled in series to a light source for supplying power to the light source; a controller electrically coupled to a switch coupled to the first inductor, the controller controlling a current flowing through the first inductor; a current sensor coupled to the first inductor and providing a first signal indicative of the current flowing through the first inductor; a second inductor coupled to the electromagnetic Inducting a power condition of the first inductor to the first inductor, the first inductor and the second inductor are electrically coupled to a common node between the switch and the first inductor, wherein The common node provides a reference ground for the controller, and the reference ground is different from the ground of the light source driving circuit; a filter coupled to the current sensor provides a first indicating an average current flowing through the first inductor a second signal; and an error amplifier that generates an error signal based on the second signal and a reference signal indicative of a target current level; wherein the error amplifier generates the error signal to adjust a current flowing through the source The target current level. The light source driving circuit of claim 1, wherein the switch is turned off if the voltage of the first signal exceeds a voltage of the error signal. The light source driving circuit of claim 2, wherein the controller generates a pulse width modulation signal to control the switch, wherein a duty cycle ratio of the pulse width modulation signal is determined by the error signal. The light source driving circuit of claim 1, wherein a ground end of the controller is coupled to the common node, wherein a conduction state of the switch is a gate voltage of the switch and the common node The voltage difference between the voltages is determined. The light source driving circuit of claim 4, wherein the switch is turned on if the current flowing through the first inductor is reduced to a preset current level. The light source driving circuit of claim 1, further comprising: a signal generator for generating a sawtooth wave signal; wherein the voltage of the sawtooth wave signal is increased to a voltage of the error signal, the switch is turned off. The light source driving circuit of claim 1, further comprising: a reset signal generator for generating a reset signal, wherein the switch is turned on to return the reset signal. The light source driving circuit of claim 7, wherein the reset signal is a pulse signal having a fixed frequency or a pulse signal having a constant time when the switch is in an off state. A controller for controlling power transmitted to a light source, comprising: a first inductive pin sensing an instantaneous current flowing through an energy storage component; and a second inductive pin sensing an average flowing through the energy storage component Current; a third inductive pin that detects whether the instantaneous current is reduced to a preset a driving pin, providing a driving signal to control a switch coupled to the driving pin, thereby controlling an average current flowing through the light source to be equal to a target current level, wherein the driving signal is based on the first sensing Generating a signal received by the pin, the second inductive pin, and the third inductive pin; and an error amplifier indicating the flow through the energy storage element based on the target current value and from the second inductive pin The average current monitoring signal produces an error signal, wherein the drive signal is also generated based on the error signal. The controller of claim 9, further comprising: a comparator coupled to the error amplifier, the error signal being compared with an induced signal from the first inductive pin indicating the instantaneous current. The controller of claim 10, further comprising: a pulse width modulation signal generator coupled to the comparator, based on an output of the comparator and from the third inductive pin, indicating whether the instantaneous current is A detection signal that is lowered to the predetermined current level produces a pulse width modulation signal. The controller of claim 9, further comprising: a signal generator for generating a sawtooth signal; and a comparator coupled to the error amplifier for comparing the error signal with a sawtooth signal. The controller of claim 12, further comprising: a reset signal generator for generating a reset signal; and a pulse width modulation signal generator coupled to the comparator, based on An output of the comparator and a reset signal generate a pulse width modulation signal. The controller of claim 13, wherein the reset signal is a pulse signal having a fixed frequency. The controller of claim 13, wherein the pulse width modulation signal has a first state and a second state, and wherein the reset signal is such that the pulse width modulation signal is in the The time of the second state is a constant pulse signal.