CN110099478B - Non-inductance step-down type LED driving circuit and method - Google Patents
Non-inductance step-down type LED driving circuit and method Download PDFInfo
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- CN110099478B CN110099478B CN201810919865.6A CN201810919865A CN110099478B CN 110099478 B CN110099478 B CN 110099478B CN 201810919865 A CN201810919865 A CN 201810919865A CN 110099478 B CN110099478 B CN 110099478B
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- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
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Abstract
The invention discloses a non-inductance step-down LED driving circuit and a method, comprising a circuit composed of a switching tube, a sampling resistor, a controller and an LED, wherein the product of reference voltage and conduction time in driving is a constant, the obtained average current of the LED is only related to a constant voltage and a current sampling resistor and is not related to input voltage, meanwhile, a linear constant current source is not used for consuming driving voltage higher than that of the LED, the LED is turned off in a period of time through a switching mode, the working frequency is usually over 10KHz, and due to light delay of human eyes, the LED driving circuit can be used for driving a plurality of LEDs in a single-phase mode. This frequency is not perceptible to a person or the light is perceived to be smooth. The method solves the problems of high cost and large volume of the traditional inductor, and also solves the problem of poor linear step-down driving efficiency of the existing constant current source without power supply.
Description
Technical Field
The invention belongs to the field of integrated circuits, and particularly relates to an inductance-free buck LED driving circuit and method.
Background
The LED lamp for green illumination has obvious advantages compared with the conventional incandescent lamp, and is now replacing the incandescent lamp and saving energy, and becoming the mainstream illumination lamp source. The driving method of the LED is different from the conventional method, the brightness and the lifetime of the LED are related to the average current thereof, and the current driving technology mainly includes two types. The first type is to realize constant current LED driving with an inductive switching type BUCK circuit (BUCK), as shown in fig. 5 and 6. This scheme is shown by. It can be seen that the advantages of this solution are power conversion efficiency and wide voltage operating range, but the disadvantages are also obvious, and due to the inductance, the cost is high and the volume is large. These two problems are a great problem in mass production and popularization of products, and therefore, there is also a linear step-down LED driving of an inductance-free constant current source type, as shown in fig. 7. The cost of this solution is rather low and the volume is small, but its power conversion efficiency is poor, especially when the input and output voltages are different relatively much.
Therefore, how to solve the above problems becomes a focus of research by those skilled in the art.
Disclosure of Invention
The invention aims to provide an inductance-free step-down LED driving circuit and method, which can effectively overcome the defects of large volume and high cost and can also achieve high power conversion efficiency.
The purpose of the invention is realized by the following technical scheme:
the utility model provides a no inductance step-down LED drive circuit, includes the circuit of compriseing switch tube M1, sampling resistor, controller, LED, input voltage Vin, sampling resistor one end is connected to input voltage Vin, the anodal and the controller of LED is connected to the sampling resistor other end, LED and controller are parallelly connected, and the D utmost point of switch tube is connected to the LED negative pole, and the G utmost point of switch tube M1 is connected to the controller, and the S utmost point ground connection of switch tube M1.
Preferably, the controller circuit is: the other end of the sampling resistor is connected with an operational amplifier, the operational amplifier is connected with a reference voltage source in series, the reference voltage source is connected with a current source I1 in series, a current source I1 is connected with a current source I2 in series, the current source I2 is connected with a capacitor in parallel, the end, connected with the current source I2, of the capacitor is grounded, the other end of the capacitor is connected with two comparators, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of a switching tube.
Preferably, the controller circuit may further include: the other end of the sampling resistor is connected with a sampling retainer, the sampling retainer is connected with the positive input end of an operational amplifier, the negative input end of the operational amplifier is connected with the output end of the operational amplifier, the output end of the operational amplifier is connected with a reference voltage source, the reference voltage source is connected with a current source I1 by making a difference with the voltage of the output end of the operational amplifier, the current source I1 is connected with a capacitor C1, the D pole of a switching tube Mdis and two comparators, the other end of the capacitor C1 is connected with the S pole of the switching tube Mdis and then grounded, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of the switching tube M1.
The non-inductive step-down LED driving circuit comprises a circuit consisting of a switch tube M1, a sampling resistor, a controller, an LED and an input voltage Vin, wherein the input voltage Vin is connected with the anode of the LED, the cathode of the LED is connected with the D pole of the switch tube M1, the G pole of the switch tube M1 is connected with the controller, the other end of the controller is connected with the S pole of the switch tube M1, one end of the sampling resistor is connected with the S pole of the switch tube M1, and the other end of the sampling resistor is grounded.
Preferably, the controller circuit is: the S pole of the switch tube M1 is connected with an operational amplifier, the operational amplifier is connected with a reference voltage source in series, the reference voltage source is connected with a current source I1, a current source I1 is connected with a current source I2, the current source I2 is connected with a capacitor, the capacitor is connected with the current source I2 end and is grounded, the other end of the capacitor is connected with two comparators, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of the switch tube.
Preferably, the controller circuit is: the S pole of the switch tube M1 is connected with a sampling holder, the sampling holder is connected with the positive input end of an operational amplifier, the direction input end of the operational amplifier is connected with the output end of the operational amplifier, the output end of the operational amplifier is connected with a reference voltage source, the voltage difference between the reference voltage source and the output end of the operational amplifier is connected with a current source I1, the current source I1 is connected with a capacitor C1, the D pole of a switch tube Mdis and two comparators, the other end of the capacitor C1 is connected with the S pole of the switch tube Mdis and then grounded, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of the switch tube M1.
A driving method of a non-inductive step-down LED comprises the following steps:
1) by the equation: (Vsen-Vref) × Ton ═ Vref × Toff and equation
Obtaining that Vsen is sampling voltage, Vref is reference voltage, Iavg is average current of the LED, Vavg is average voltage on the sampling resistor, Ton is on-time of the switching tube, Toff is off-time of the switching tube, and the time product of the voltage of the sampling resistor in the on-time period of the switching tube is equal to the time product of the off-time of the switching tube, and the time product of the voltage converted into the current is equal to the time product of the on-time period of the switching tube.
2) The product of the internal capacitance of the controller and the voltage is made to be a constant.
3) The turn-off frequency of the switching tube is 100Hz-200 MHz.
Compared with the prior art, the invention has the beneficial effects that:
aiming at the problem that the cost, the volume and the efficiency cannot be considered in the prior art, the invention provides a switching type inductance-free step-down LED driving method according to the characteristic that an LED needs constant average current, and the innovation of the product is as follows: the LED driving circuit omits an inductor, and simultaneously adopts the working mode of a switch, so that the LED works under constant average current without being influenced by power supply voltage, and the conversion efficiency is improved.
Drawings
FIG. 1 is a diagram of an application of the present invention;
FIG. 2 is a graph of current sample voltage versus reference voltage waveforms;
FIG. 3 is a control current block diagram of the present invention;
FIG. 4 is a diagram of a second control current configuration;
FIG. 5 is a diagram of a conventional synchronous buck LED driver configuration with inductor;
FIG. 6 is a block diagram of another form of conventional synchronous buck LED drive with inductor;
FIG. 7 is a diagram of a prior art linear constant current source LED driving method;
fig. 8 is another application diagram of the present invention.
Detailed Description
The invention will be further described with reference to specific embodiments and the accompanying drawings.
Example one
As shown in fig. 8, referring to fig. 2 to 4, the circuit of the controller portion, a non-inductive step-down LED driving circuit, includes a circuit composed of a switching tube M1, a sampling resistor, a controller, an LED, and an input voltage Vin, the input voltage Vin is connected to one end of the sampling resistor, the other end of the sampling resistor is connected to the positive electrode of the LED and the controller, the LED and the controller are connected in parallel, the negative electrode of the LED is connected to the D electrode of the switching tube, the controller is connected to the G electrode of the switching tube M1, and the S electrode of the switching tube M1 is grounded. The controller circuit is: the other end of the sampling resistor is connected with an operational amplifier, the operational amplifier is connected with a reference voltage source in series, the reference voltage source is connected with a current source I1 in series, a current source I1 is connected with a current source I2 in series, the current source I2 is connected with a capacitor in parallel, the end, connected with the current source I2, of the capacitor is grounded, the other end of the capacitor is connected with two comparators, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of a switching tube.
In this embodiment, as can be seen from fig. 2, the total average current is the area enclosed under Vref, except the area in Toff, such as the area in Ton time, so there is the following equation:
(Vsen-Vref)×Ton＝Vref×Toff
it is obtained that Vsen is the sampling voltage, Vref is the reference voltage, Iavg is the average current output by the LED, Vavg is the average voltage across the sampling resistor, Ton is the on-time of the switch, Toff is the off-time of the switch, and to make the time products of the two voltages equal, the time products of the two voltages can be converted to be equal, and the product of the capacitance and the voltage is a constant. The above equation can be implemented such that the resulting average current of the LED is one that is only related to the constant voltage and current sampling resistance, and no longer related to the input voltage VIN. Meanwhile, the driving voltage higher than that of the LED is consumed by the linear constant current source, the LED is turned off within a period of time in a switch mode, the working frequency is usually over 10KHz, and due to the light delay of human eyes, the LED driving circuit is not easy to be damaged. This frequency is not perceptible to a person or the light is perceived to be smooth.
From the waveforms and the current-voltage characteristics of the LED lamp, it can be seen that when the voltage is high, the on time is short and the off time is long. While at low voltages, the on-time is long and the off-time is short.
Example two
As shown in fig. 8, referring to fig. 2 to 4, the circuit of the controller portion, a non-inductive step-down LED driving circuit, includes a circuit composed of a switching tube M1, a sampling resistor, a controller, an LED, and an input voltage Vin, the input voltage Vin is connected to one end of the sampling resistor, the other end of the sampling resistor is connected to the positive electrode of the LED and the controller, the LED and the controller are connected in parallel, the negative electrode of the LED is connected to the D electrode of the switching tube, the controller is connected to the G electrode of the switching tube M1, and the S electrode of the switching tube M1 is grounded. The controller circuit is: the other end of the sampling resistor is connected with a sampling retainer, the sampling retainer is connected with the positive input end of an operational amplifier, the direction input end of the operational amplifier is connected with the output end of the operational amplifier, the output end of the operational amplifier is connected with a reference voltage source, the reference voltage source is connected with a current source I1 by making a difference with the voltage of the output end of the operational amplifier, the current source I1 is connected with a capacitor C1, the D pole of a switching tube Mdis and two comparators, the other end of the capacitor C1 is connected with the S pole of the switching tube Mdis and then grounded, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of the switching tube M1.
In the present embodiment, the magnitudes of the currents of the two current sources I1 and I2 are set by the sampling voltage Vsen and the reference voltage Vref, and assuming that the voltage-current ratio (impedance) is R0, I1 is (Vsen-Vref)/R0, and I2 is Vref/R0. When the switch M1 is turned on, the current I1 charges the capacitor C1, and the charging duration is finally Ton ═ (Vref1-Vref2) × C1/I1, where Vref1 is the voltage of the comparator connected to the R terminal of the flip-flop, and Vref2 is the voltage of the comparator connected to the S terminal of the flip-flop. When the switch M1 is turned off, the current I2 discharges the capacitor C1, and the discharge time is finally Toff ═ (Vref1-Vref2) × C1/I2, where Vref1 is the voltage of the comparator connected to the R terminal of the flip-flop, and Vref2 is the voltage of the comparator connected to the S terminal of the flip-flop. The current flowing through the LED lamp flows through the sampling resistor through the conducting switch M1, and the sampling voltage Vsen is obtained by sampling and holding the voltage across the sampling resistor, where Vsen is Iout Rsen, where Iout is the current flowing out of the controller. Through the circuit, the average current Iavg which is equal to Vref/Rsen can be finally realized to flow through the LED lamp. Thereby achieving the design objective.
EXAMPLE III
As shown in fig. 1 to 4, an inductance-free step-down LED driving circuit includes a circuit composed of a switching tube M1, a sampling resistor, a controller, an LED, and an input voltage Vin, where the input voltage Vin is connected to an anode of the LED, a cathode of the LED is connected to a D-pole of the switching tube M1, a G-pole of the switching tube M1 is connected to the controller, another end of the controller is connected to an S-pole of the switching tube M1, one end of the sampling resistor is connected to the S-pole of the switching tube M1, and another end of the sampling resistor is grounded. The controller circuit is: the S pole of the switch tube M1 is connected with an operational amplifier, the operational amplifier is connected with a reference voltage source in series, the reference voltage source is connected with a current source I1 in series, a current source I1 is connected with a current source I2 in series, a capacitor is connected with the current source I2 in parallel, the end of the capacitor connected with the current source I2 is grounded, the other end of the capacitor is connected with two comparators, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of the switch tube M1.
In this embodiment, the current of the two current sources I1 and I2 is set by the sampling voltage Vsen and the reference voltage Vref, and assuming that the voltage-current ratio (impedance) is R0, I1 is (Vsen-Vref)/R0, and I2 is Vref/R0. When the switch M1 is turned on, the current I1 charges the capacitor C1, and the charging duration is finally Ton ═ (Vref1-Vref2) × C1/I1, where Vref1 is the voltage of the comparator connected to the R terminal of the flip-flop, and Vref2 is the voltage of the comparator connected to the S terminal of the flip-flop. When the switch M1 is turned off, the current I2 discharges the capacitor C1, and the discharge time is finally Toff ═ (Vref1-Vref2) × C1/I2, where Vref1 is the voltage of the comparator connected to the R terminal of the flip-flop, and Vref2 is the voltage of the comparator connected to the S terminal of the flip-flop. The current flowing through the LED lamp flows through the sampling resistor through the conducting switch M1, and the sampling voltage Vsen is obtained by sampling and holding the voltage across the sampling resistor, where Vsen is Iout Rsen, where Iout is the current flowing out of the controller. Through the circuit, the average current Iavg which is equal to Vref/Rsen can be finally realized to flow through the LED lamp. Thereby achieving the design objective. (source of VDD in the figure and technical problem to be solved) (sample-and-hold circuit)
Example four
As shown in fig. 1 to 4, an inductance-free step-down LED driving circuit includes a circuit composed of a switching tube M1, a sampling resistor, a controller, an LED, and an input voltage Vin, where the input voltage Vin is connected to an anode of the LED, a cathode of the LED is connected to a D-pole of the switching tube M1, a G-pole of the switching tube M1 is connected to the controller, another end of the controller is connected to an S-pole of the switching tube M1, one end of the sampling resistor is connected to the S-pole of the switching tube M1, and another end of the sampling resistor is grounded. The controller circuit is: the S pole of the switch tube M1 is connected with a sampling holder, the sampling holder is connected with the positive input end of an operational amplifier, the direction input end of the operational amplifier is connected with the output end of the operational amplifier, the output end of the operational amplifier is connected with a reference voltage source, the voltage difference between the reference voltage source and the output end of the operational amplifier is connected with a current source I1, the current source I1 is connected with a capacitor C1, the D pole of a switch tube Mdis and two comparators, the other end of the capacitor C1 is connected with the S pole of the switch tube Mdis and then grounded, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of the switch tube M1.
In the present embodiment, the magnitudes of the currents of the two current sources I1 and I2 are set by the sampling voltage Vsen and the reference voltage Vref, and assuming that the voltage-current ratio (impedance) is R0, I1 is (Vsen-Vref)/R0, and I2 is Vref/R0. When the switch M1 is turned on, the current I1 charges the capacitor C1, and the charging duration is finally Ton ═ (Vref1-Vref2) × C1/I1, where Vref1 is the voltage of the comparator connected to the R terminal of the flip-flop, and Vref2 is the voltage of the comparator connected to the S terminal of the flip-flop. When the switch M1 is turned off, the current I2 discharges the capacitor C1, and the discharge time is finally Toff (Vref1-Vref2) C1/I2, where Vref1 is the voltage of the comparator connected to the R terminal of the flip-flop, and Vref2 is the voltage of the comparator connected to the S terminal of the flip-flop. The current flowing through the LED lamp flows through the sampling resistor through the conducting switch M1, and the sampling voltage Vsen is obtained by sampling and holding the voltage across the sampling resistor, where Vsen is Iout Rsen, where Iout is the current flowing out of the controller. Through the circuit, the average current Iavg which is equal to Vref/Rsen can be finally realized to flow through the LED lamp. Thereby achieving the design objective.
EXAMPLE five
As can be seen from fig. 2, in a method of driving the non-inductive step-down LED, the total average current is the area enclosed under Vref, except the area within Toff, such as the area within Ton, and therefore, the following equation is given.
1) By the equation: (Vsen-Vref) × Ton ═ Vref × Toff and equation
Obtaining that Vsen is a sampling voltage, Vref is a reference voltage, Iavg is an average current output by the LED, Vavg is an average voltage on the sampling resistor, Ton is a switch tube on-time, Toff is a switch tube off-time, and the time product of the voltage of the sampling resistor in the switch tube on-time period is equal to the time product of the switch tube off-time, and the time product of the voltage converted into the current is equal to the time product of the current.
2) The product of the internal capacitance of the controller and the voltage is made to be a constant.
3) The turn-off frequency of the switching tube is 100Hz-200 MHz.
The two voltage time products are made equal. The above equation can be implemented by switching to make the current-time products equal, i.e., the product of the capacitance and the voltage is a constant, and the resulting average current of the LED is a constant voltage and current sampling resistor only, and is no longer related to the input voltage VIN. Meanwhile, a linear constant current source is not used for consuming the driving voltage higher than that of the LED, the LED is turned off within a period of time in a switch mode, and the working frequency is usually over 10 KHz.
In this embodiment, the light is delayed by the human eye. The frequency is not sensed by people or the lamp light is sensed to be stable, and the waveform and the volt-ampere characteristic of the LED lamp show that the on-state time is short and the off-state time is long when the voltage is high, and the on-state time is long and the off-state time is short when the voltage is low.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (5)
1. The utility model provides a no inductance step-down LED drive circuit which characterized in that: the LED sampling circuit comprises a circuit consisting of a switching tube M1, a sampling resistor, a controller, an LED and an input voltage Vin, wherein the input voltage Vin is connected with one end of the sampling resistor, the other end of the sampling resistor is connected with the anode of the LED and the controller, the LED is connected with the controller in parallel, the cathode of the LED is connected with the D pole of the switching tube M1, the controller is connected with the G pole of the switching tube M1, and the S pole of the switching tube M1 is grounded; the circuit of the controller is as follows: the other end of the sampling resistor is connected with an operational amplifier, the operational amplifier is connected with a reference voltage source in series, the reference voltage source is connected with a current source I1 in series, a current source I1 is connected with a current source I2 in series, the current source I2 is connected with a capacitor in parallel, one end of the capacitor, which is connected with the current source I2, is grounded, the other end of the capacitor is connected with two comparators, the output ends of the two comparators are respectively connected with the R end and the S end of a trigger, and the output end of the trigger is connected with the G pole of a switch tube M1.
2. The non-inductive buck LED driving circuit according to claim 1, wherein: the circuit of the controller may further be: the other end of the sampling resistor is connected with a sampling holder, the sampling holder is connected with the forward input end of an operational amplifier, the reverse input end of the operational amplifier is connected with the output end of the operational amplifier, the output end of the operational amplifier is connected with a reference voltage source, the reference voltage source is connected with a current source I1 through a voltage difference of the output end of the operational amplifier, the current source I1 is further connected with a capacitor C1, the D pole of a switching tube Mdis and two comparators, the other end of the capacitor C1 is connected with the S pole of the switching tube Mdis in parallel, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of the switching tube M1.
3. The utility model provides a no inductance step-down LED drive circuit which characterized in that: the LED constant current source comprises a circuit consisting of a switching tube M1, a sampling resistor, a controller, an LED and an input voltage Vin, wherein the input voltage Vin is connected with the anode of the LED, the cathode of the LED is connected with the D pole of a switching tube M1, the G pole of the switching tube M1 is connected with the controller, the other end of the controller is connected with the S pole of the switching tube M1, one end of the sampling resistor is connected with the S pole of the switching tube M1, and the other end of the sampling resistor is grounded; the circuit of the controller is as follows: the S pole of the switch tube M1 is connected with an operational amplifier, the operational amplifier is connected with a reference voltage source in series, the reference voltage source is connected with a current source I1, a current source I1 is connected with a current source I2, the current source I2 is connected with a capacitor, the capacitor is connected with the current source I2 end and is grounded, the other end of the capacitor is connected with two comparators, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of the switch tube.
4. The non-inductive buck LED driving circuit according to claim 3, wherein: the circuit of the controller may further be: the S pole of the switch tube M1 is connected with a sampling holder, the sampling holder is connected with the positive input end of an operational amplifier, the direction input end of the operational amplifier is connected with the output end of the operational amplifier, the output end of the operational amplifier is connected with a reference voltage source, the voltage difference between the reference voltage source and the output end of the operational amplifier is connected with a current source I1, the current source I1 is connected with a capacitor C1, the D pole of a switch tube Mdis and two comparators, the other end of the capacitor C1 is connected with the S pole of the switch tube Mdis and then grounded, the output ends of the two comparators are respectively connected with the R end and the S end of a flip-flop, and the output end of the flip-flop is connected with the G pole of the switch tube M1.
5. A non-inductive step-down LED driving method based on the circuit of claim 1 or claim 3, characterized in that:
1) by the equation: (Vsen-Vref) × Ton ═ Vref × Toff and equation
Obtaining that Vsen is a sampling voltage, Vref is a reference voltage, Iavg is an average current output by an LED, Vavg is an average voltage on a sampling resistor, Ton is a switching tube on-time, Toff is a switching tube off-time, and a time product of the voltage of the sampling resistor in the switching tube on-time period is equal to a time product of the switching tube off-time and is converted into a current;
2) making the product of the internal capacitance of the controller and the voltage a constant;
3) the turn-off frequency of the switching tube is 100Hz-200 MHz.
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| CN102651936A (en) * | 2011-02-24 | 2012-08-29 | 汉能科技股份有限公司 | Light emitting diode driving circuit |
| CN103269550A (en) * | 2013-06-04 | 2013-08-28 | 上海晶丰明源半导体有限公司 | LED ((Light Emitting Diode) current ripple elimination driving circuit |
| CN103428969A (en) * | 2013-08-15 | 2013-12-04 | 辉芒微电子（深圳）有限公司 | Linear constant current light-emitting diode (LED) driving circuit and LED lamp |
| CN107371299A (en) * | 2017-08-29 | 2017-11-21 | 无锡麟力科技有限公司 | The linear constant current LED drive circuit and driving method of a kind of High Power Factor |
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