CN203590562U - LED switch constant current driving circuit - Google Patents

LED switch constant current driving circuit Download PDF

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Publication number
CN203590562U
CN203590562U CN201320756821.9U CN201320756821U CN203590562U CN 203590562 U CN203590562 U CN 203590562U CN 201320756821 U CN201320756821 U CN 201320756821U CN 203590562 U CN203590562 U CN 203590562U
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CN
China
Prior art keywords
voltage
led
output
power tube
drive circuit
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Expired - Fee Related
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CN201320756821.9U
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Chinese (zh)
Inventor
严守平
蔡晓辉
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SHANGHAI LAITUOSI ELECTRONIC TECHNOLOGY Co Ltd
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SHANGHAI LAITUOSI ELECTRONIC TECHNOLOGY Co Ltd
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Abstract

The utility model provides a LED switch constant current driving circuit. The LED switch constant current driving circuit at least comprises a voltage input module, a LED module, a power tube, a filter, an error amplifier, a pulse width modulation circuit, a current restriction circuit, a control circuit and a driving circuit, wherein the LED module is connected to the voltage input module; the power tube is connected to the LED module; through adjusting a switch duty ratio of the power tube, the constant current can be realized; the filter is connected to an output terminal of the power tube and is used for carrying out filtering on a sampling voltage; the error amplifier compares the sampling voltage and a reference voltage; the pulse width modulation circuit generates a PWM signal; the current restriction circuit adjusts a PWM signal amplitude; the control circuit and the driving circuit are used for adjusting and driving a power tube gate voltage. According to the circuit of the utility model, through a new topology structure of combining a switch and a linearity, the LED constant current is realized; an inductor and an electrolytic capacitor are not needed; a switch mode is used to control the power tube and efficiency is higher than efficiency of a pure linear control architecture.

Description

A kind of LED switch constant-current drive circuit
Technical field
The utility model relates to LED Drive Control Technique field, particularly relates to a kind of LED switch constant-current drive circuit.
Background technology
LED because having advantages of that efficiency is high, the life-span is long, not cracky, switching speed is high, reliability is high etc., and conventional light source is too late, has been widely used in indicator light, display and lighting field.
LED is the semiconductor device of working under a kind of low-voltage direct condition.For illumination application, external voltage need be greater than the positive drive voltage VF value of LED, needs to make LED diode operation under constant current condition by a constant-current control circuit, to realize the application requirements of illumination simultaneously.When input voltage is during higher than the VF of LED, generally can adopt so-called Buck reduction voltage circuit to make voltage be down to consistent with VF and make it work; Otherwise, when input voltage is during lower than the VF of LED, must adopt Boost booster circuit that voltage and VF are matched, thereby realize normal constant current control work.
Be as shown in Figure 1 the LED constant-current drive circuit of Buck switch configuration conventional in conventional art, the driving signal of 11 conductings of control switch pipe and cut-off is generally PWM(pulse-width modulation) signal, when driving signal to make switching tube 11 conducting, capacitor C starts charging, and output voltage is added on LED lamp string 12.Capacitor C electric current of inductance L in charging process increases gradually, and the energy of storage also increases gradually, and now sustained diode is oppositely ended.When driving signal to make switching tube 11 cut-off, start to release energy, electric current in inductance L starts to reduce, the induced electromotive force producing makes sustained diode conducting, electric current is by inductance L, sustained diode, form loop to LED lamp string 12 transferring energies, the voltage on LED lamp string 12 is lower than input voltage.Be as shown in Figure 2 the LED constant-current drive circuit of Boost switch configuration conventional in conventional art, when driving signal to make switching tube 21 conducting, capacitor C starts charging, input voltage flows through inductance L, diode D prevents that capacitor C from discharging over the ground, electric current in inductance L increases gradually, along with inductive current increases, has stored some energy in inductance L.When driving signal to make switching tube 21 cut-off, due to the electric current retention performance of inductance L, inductance L starts slowly to capacitor C charging, capacitor C both end voltage raises, and now the voltage on LED lamp string 22 is higher than input voltage.But the LED constant-current drive circuit of Buck and Boost switch topology need to be used the energy storage devices such as inductance, electric capacity, application designs relative complex, but also affects the useful life of light fixture.
Linear Control is another the common topology that is different from Buck and Boost switch topology, and it avoids using inductance, but makes electric current and the voltage of LED lamp string remain on set point by the conduction impedance of power ratio control pipe.As shown in Figure 3, with the continuous increase of input voltage, the electric current that flows through LED lamp string 32 constantly increases, when the voltage on detecting resistance R cs is greater than reference voltage Vref, error amplifier 33 output control signals increase the conduction impedance of power tube 31, and the electric current that flows through LED lamp string 32 reduces; When the voltage on detecting resistance R cs is less than reference voltage Vref, error amplifier 33 output control signals reduce the conduction impedance of power tube 31, and the electric current that flows through LED lamp string 32 increases; Adjusting by this power tube conduction impedance size makes the electric current that flows through LED lamp string keep constant.Because flow through the electric current of LED lamp string, equal input current, so in fact the efficiency of Linear Control be exactly the ratio that LED lamp string is pressed Vled and input voltage vin, when particularly the difference of Vin and Vled is larger, this difference all drops on power tube, power consumption is very large, and therefore the shortcoming of this Linear Control is that efficiency is lower.
The LED constant-current drive circuit of Buck and Boost switch topology need to be used the energy storage devices such as inductance, electric capacity, and application designs relative complex, but also affects the useful life of light fixture.The LED constant-current drive circuit design of Linear Control topological structure is relatively simple, to not exerting an influence the useful life of light fixture, but efficiency low be the major defect of this topological structure.These are basic restrictions that this type of LED constant current at present drives control chip, how to design a kind of application simplicity of design, lamp life is not exerted an influence, having again more high efficiency LED constant-current drive circuit simultaneously becomes present LED driving design field urgent problem.
Utility model content
The shortcoming of prior art in view of the above, the purpose of this utility model is to provide a kind of LED switch constant-current drive circuit, for solving the LED constant-current drive circuit of prior art Buck and Boost switch topology, need to use the energy storage devices such as inductance, electric capacity, application designs relative complex, affects the useful life of light fixture; The problem such as the LED constant-current drive circuit efficiency of Linear Control is lower.
For achieving the above object and other relevant objects, the utility model provides a kind of LED switch constant-current drive circuit, and described LED switch constant-current drive circuit at least comprises:
Voltage input module, for providing adjustable input voltage;
LED module, is connected in described voltage input module;
Power tube, is connected in described LED module, by regulating the duty cycle of switching of this power tube can realize the constant current of described LED module;
Filter, is connected in the output of described power tube, for the output signal of described power tube is carried out to filtering;
Be connected in the error amplifier of described filter output, for the output voltage of described filter and reference voltage are compared, and comparative result amplified to output;
Pulse width modulation circuit, is connected in described error amplifier output and is connected with an oscillator, by Output rusults and the described oscillator acting in conjunction generation pwm signal of described error amplifier, for regulating the duty ratio of the switching signal of described power tube;
Current limit circuit, is connected in the output of described power tube, for limiting the peak current that flows through described LED module, adjusts the amplitude of the switching signal of described power tube;
Control circuit, described control circuit is connected in described pulse width modulation circuit and described current limit circuit, integrates duty ratio and the amplitude of signal of the switch of described power tube by the signal of described pulse width modulation circuit and described current limit circuit output;
Drive circuit, is connected between described control circuit and the control end of described power tube, for driving the gate voltage of described power tube.
Preferably, described voltage input module comprises an AC power and a rectification unit, described rectification unit comprises two groups of diode groups in parallel, and each diode group comprises two diodes of series connection, and the two poles of the earth of described AC power are connected between two diodes of each diode group.
Preferably, the voltage of described voltage input module output is for increasing continuously or reducing continuously.
Preferably, the voltage of described voltage input module output is the commutating voltage after sinusoidal voltage rectification.
Preferably, also comprise a filter capacitor, described filter capacitor one end is connected with the output of described voltage input module, other end ground connection.
Preferably, also comprise a building-out capacitor, described building-out capacitor one end is connected with the output of described filter, and other end ground connection, for stablizing the output voltage of described filter.
Preferably, also comprise a detection resistance, described detection resistance one end is connected with the output of described power tube, and other end ground connection, for being voltage signal by the current conversion of the described LED module of flowing through.
Preferably, also comprise a building-out capacitor, described building-out capacitor one end is connected with the output of described error amplifier, and other end ground connection, for stablizing the output voltage of described error amplifier.
Preferably, also comprise a filter capacitor, described filter capacitor is parallel to described LED module.
Preferably, described reference voltage is default definite value or changing value.
As mentioned above, a kind of LED switch constant-current drive circuit of the present utility model, there is following beneficial effect: the utility model is in conjunction with the advantage separately of switch topology and linear topology, abandon two kinds of topologys shortcoming separately, the new topological structure that has formed a kind of switch and linear combination is realized the constant current of LED, do not need inductance completely, also can save electrochemical capacitor, adopt the mode of switch to carry out power ratio control pipe simultaneously, application simplicity of design, do not affect useful life of light fixture, efficiency is higher than the control framework of pure linearity simultaneously.
Accompanying drawing explanation
Fig. 1 is shown as the LED constant-current drive circuit schematic diagram of Buck switch configuration of the prior art.
Fig. 2 is shown as the LED constant-current drive circuit schematic diagram of Boost switch configuration of the prior art.
Fig. 3 is shown as the LED constant-current drive circuit schematic diagram of Linear Control of the prior art.
Fig. 4 is shown as the schematic diagram that does not connect filter capacitor after the voltage input module of LED switch constant-current drive circuit of the present utility model.
Fig. 5 is shown as the schematic diagram that connects filter capacitor after the voltage input module of LED switch constant-current drive circuit of the present utility model.
Fig. 6 is shown as the waveform schematic diagram of the input voltage vin after the rectification of LED switch constant-current drive circuit of the present utility model.
Fig. 7 is shown as detection voltage Vcs, the voltage Vfb of filter output and the waveform schematic diagram of reference voltage Vref of LED switch constant-current drive circuit of the present utility model.
Fig. 8 is shown as the waveform schematic diagram of the error amplification signal Vcomp of LED switch constant-current drive circuit of the present utility model.
Fig. 9 is shown as the waveform schematic diagram of the power tube gate voltage Vgate of LED switch constant-current drive circuit of the present utility model.
Element numbers explanation
The LED constant-current drive circuit of 1 Buck switch configuration
11 switching tubes
12 LED lamp strings
The LED constant-current drive circuit of 2 Boost switch configurations
21 switching tubes
22 LED lamp strings
The LED constant-current drive circuit of 3 Linear Control
31 power tubes
32 LED lamp strings
33 error amplifiers
4 LED switch constant-current drive circuits
41 voltage input modules
42 LED modules
M power tube
43 filters
44 error amplifiers
45 pulse width modulation circuits
46 oscillators
47 current limit circuits
48 control circuits
49 drive circuits
Embodiment
By specific instantiation, execution mode of the present utility model is described below, those skilled in the art can understand other advantages of the present utility model and effect easily by the disclosed content of this specification.The utility model can also be implemented or be applied by other different embodiment, and the every details in this specification also can be based on different viewpoints and application, carries out various modifications or change not deviating under spirit of the present utility model.
Refer to Fig. 4 to Fig. 9.It should be noted that, the diagram providing in the present embodiment only illustrates basic conception of the present utility model in a schematic way, satisfy and only show with assembly relevant in the utility model in graphic but not component count, shape and size drafting while implementing according to reality, during its actual enforcement, kenel, quantity and the ratio of each assembly can be a kind of random change, and its assembly layout kenel also may be more complicated.
As shown in Figure 4, the utility model provides a kind of LED switch constant-current drive circuit 4, and described LED switch constant-current drive circuit 4 at least comprises: voltage input module 41; LED module 42; Power tube M; Filter 43; Error amplifier 44; Pulse width modulation circuit 45; Oscillator 46; Current limit circuit 47; Control circuit 48 and drive circuit 49.
Described voltage input module 41, for providing adjustable input voltage Vin.
As shown in Figure 4, described voltage input module comprises an AC power AC and a rectification unit, described rectification unit comprises two groups of diode groups in parallel, and each diode group comprises two diodes of series connection, and the two poles of the earth of described AC power are connected between two diodes of each diode group.The voltage of described voltage input module 41 outputs is the commutating voltage after the continuous sinusoidal voltage rectification that increases or reduce continuously.As shown in Figure 6, described rectification circuit carries out the reverse voltage of sinusoidal voltage oppositely, two sections of forward alternating voltage Vin that the cycle that obtains is identical.
The output of described voltage input module 41 can connect filter capacitor also can not connect filter capacitor, be illustrated in figure 4 the schematic diagram that does not connect filter capacitor after the voltage input module of LED switch constant-current drive circuit of the present utility model, Vin is not with the output voltage of jumbo filter capacitor after sinusoidal voltage rectification.Be illustrated in figure 5 the schematic diagram that connects filter capacitor after the voltage input module of LED switch constant-current drive circuit of the present utility model, filter capacitor C4 one end is connected with the output of described voltage input module, other end ground connection.
Described LED module 42 is connected in described voltage input module 41, as lighting apparatus.
As shown in Figure 4, described LED module 42 is comprised of the LED lamp of 3 series connection, and the two ends of described LED module 42 are parallel with filter capacitor C3, and described filter capacitor C3 is used for preventing surge phenomenon, and protection LED module is operated under stable state.
Described power tube M is connected in described LED module 42, and by regulating the duty cycle of switching of this power tube M can realize the constant current of described LED module 42, described power tube M is controlled by described drive circuit 49.
As shown in Figure 4, the output of described power tube M is also connected with and detects resistance R cs, and one end of described detection resistance R cs is connected with the output of described power tube M, and other end ground connection, for being voltage signal Vcs by the current conversion of the described LED module 42 of flowing through.
As shown in Figure 4, described filter 43 is connected in the output of described power tube M, for the output signal of described power tube M is carried out to filtering.The output of described filter 43 is also connected with building-out capacitor C2, and an end of building-out capacitor C2 is connected to the output of filter 43, other end ground connection, the input voltage Vfb of energy steady state error amplifier 44.
As shown in Figure 4, the input of described error amplifier 44 connects respectively output and the reference voltage Vref of described filter 43, the output voltage of described filter 43 and reference voltage Vref are compared, and produce error and amplify voltage Vcomp, described error is amplified voltage Vcomp for adjusting the duty ratio of switching signal, the output of described error amplifier 44 is also connected with building-out capacitor C1, the output of error amplifier 44 described in a termination of described building-out capacitor C1, other end ground connection, for stablizing the output voltage V comp of described error amplifier 44.
As shown in Figure 4, described pulse width modulation circuit 45 is connected in described error amplifier 44 and is connected with an oscillator 46, Output rusults and 46 actings in conjunction of described oscillator by described error amplifier 44 produce pwm signal, for regulating the duty ratio of the switching signal of described power tube M.
As shown in Figure 4, described current limit circuit 47 is connected in the output of described power tube M, for limiting the peak current that flows through described LED module 42, adjusts the amplitude of the switching signal of described power tube M.
As shown in Figure 4, after described control circuit 48 is connected in described pulse width modulation circuit 45 and described current limit circuit 47, by the signal of described pulse width modulation circuit 45 and 47 outputs of described current limit circuit, integrate duty ratio and the amplitude of the switching signal of described power tube M, obtain a new switching signal, the duty ratio of this switching signal is controlled by the pwm signal of described pulse width modulation circuit 45 outputs, the amplitude of this switching signal is controlled by the output signal of described current limit circuit 47, being illustrated in figure 9 duty ratio is 50%, amplitude is the switching signal of 5V.This switching signal is controlled conducting and the shutoff of described power tube M, and then adjusts the electric current that flows through LED module 42.
As shown in Figure 4, described drive circuit 49 is connected between described control circuit 48 and the control end of described power tube M, for driving the gate voltage of described power tube M.
The operation principle of above-mentioned LED switch constant-current drive circuit 4 is as follows:
As shown in Figure 6, after the rectification of alternating voltage by diode, export, in the present embodiment Vin be after sinusoidal voltage rectification not with the output voltage of jumbo filter capacitor, it is one-period that this waveform be take front half period of sinusoidal signal.As shown in Figure 4, after chip enable, the normal work of internal power source voltage, power tube M conducting.The value of input voltage vin increases continuously, when input voltage vin reaches the VF of LED module 42, LED module 42 is switched on, on power tube M, there is electric current to pass through, this electric current shows as and detects voltage Vcs on detection resistance R cs, this voltage Vcs has reflected the curent change that flows through LED module 42, the voltage waveform that presents similar LED current waveform, because the signal of power ratio control pipe gate voltage is the pulse signal with certain duty ratio, so as shown in Figure 7, electric current flows through while detecting resistance R cs and can produce the pulsed detection voltage Vcs with similar input voltage envelope.This voltage waveform is after device 43 carries out preliminary filtering after filtering, filtering high-frequency signal, as shown in Figure 7, the Vcs waveform of pulsed has been converted into certain ripple, the low frequency signal Vfb consistent with the frequency of input voltage, Vfb during Simultaneous Stabilization and the Vcs mean value in a twice power frequency period is consistent.Vfb is admitted to the input of error amplifier 44, another input of error amplifier 44 is reference voltage V ref, reference voltage V ref can be predefined definite value, also can be changing value, in the present embodiment, reference voltage V ref is predefined definite value, and as shown in Figure 7, reference voltage V ref is definite value in a twice power frequency period.Error amplifier 44 compares Vfb and reference voltage Vref, and error result Vcomp is amplified to output, the output COMP of error amplifier 44 is also connected with a larger building-out capacitor C1, make the error signal Vcomp that in a twice power frequency period, COMP holds after system stability keep constant, as shown in Figure 8.The oscillator signal co-controlling pulse width modulation circuit 45 that the output error signal Vcomp of error amplifier 44 produces with oscillator 46 produces the pwm signal relevant with error signal Vcomp.Simultaneously, current limit circuit 47 detects the electric current that flows through LED module 42 in real time, according to the size of this electric current, adjust the voltage swing in loop, the pwm signal that pulse width modulation circuit 45 produces and current limit circuit 47 produce voltage adjustment signal and produce one group of switching signal that has certain duty ratio and amplitude by control circuit 48, via drive circuit 49, act on again the grid of power tube M, conducting and the cut-off of power ratio control pipe M, as shown in Figure 9, this grid voltage Vgate is the switch modulation signal with certain duty ratio.Conducting and the shutoff of duty cycling power pipe M by different switching signals, the conducting degree of amplitude power ratio control pipe M by different switching signals, further reach the object that regulates the size of current that flows through LED module 42, make this electric current for constant current value in the cycle time more than 10ms of coupling LED module 42 operating voltage VF.Meanwhile, as shown in Figure 4, LED module 42 is parallel with filter capacitor C3, can effectively prevent surge phenomenon, and protection LED module is operated under stable state.
When input voltage changes, the electric current that flows through LED during switch conduction can be correspondingly different, and present the relation changing in the same way.What adopt due to the utility model is the mode that switch is controlled, and the electric current that therefore flows through LED presents pulsed, and because the peak current of LED under different input voltages is different, so the LED current peak of pulsed presents the shape of similar input voltage.Due to the existence of error amplifier 44, simultaneously at COMP end, connect larger building-out capacitor C1, not only reached the effect of amplifying, also reached the effect of active filter, thereby the mean value of having realized Vfb is tightly followed Vref, thereby realized the constant current of LED.The average current Iled_avg=Vcs_avg/Rcs=Vfb_avg/Rcs=Vref/Rcs of LED.
Be more than single cycle 10ms with the interior course of work, Fig. 6 to Fig. 9 is Vin, Vcs, Vfb, Vref, the waveform schematic diagram of each point voltage of Vcomp, Vgate in a twice power frequency period, other time is the work in this cycle of repetition.
In sum, the new topological structure that LED switch constant-current drive circuit of the present utility model has formed a kind of switch and linear combination is realized the constant current of LED.AC-input voltage can not need electrochemical capacitor to carry out filtering after over commutation, do not need inductance yet, directly be connected on LED lamp string, by the duty cycle of switching of power ratio control pipe, realize constant in the cycle time more than 10ms of LED average current, while is because LED voltage and current is non-linear, the electric current that flows through LED as voltage Vin during less times greater than the VF of LED sharply increases, excessive electric current can injure LED, but in suitable voltage range, just can not injure LED as long as limit maximum peak current by current limit circuit.Duty cycle of switching by power tube changes, electric current flows through while detecting resistance R cs can produce the pulsed voltage Vcs with similar input voltage envelope, after simple filtering, be input to again the input of amplifier, by amplifier output COMP pin, be connected to the building-out capacitor on ground, stablize loop and produce pwm signal, the variation of the duty cycle of switching of power ratio control pipe, thus the average current in the cycle time of assurance 10ms left and right is constant.The utility model has the advantages that and do not need inductance completely, also can save electrochemical capacitor, adopt the mode of switch to carry out power ratio control pipe simultaneously, application simplicity of design, do not affect useful life of light fixture, efficiency is higher than the control framework of pure linearity simultaneously.So the utility model has effectively overcome various shortcoming of the prior art and tool high industrial utilization.
Above-described embodiment is illustrative principle of the present utility model and effect thereof only, but not for limiting the utility model.Any person skilled in the art scholar all can, under spirit of the present utility model and category, modify or change above-described embodiment.Therefore, have in technical field under such as and conventionally know that the knowledgeable modifies or changes not departing from all equivalences that complete under spirit that the utility model discloses and technological thought, must be contained by claim of the present utility model.

Claims (10)

1. a LED switch constant-current drive circuit, is characterized in that, described LED switch constant-current drive circuit at least comprises:
Voltage input module, for providing adjustable input voltage;
LED module, is connected in described voltage input module;
Power tube, is connected in described LED module, by regulating the duty cycle of switching of this power tube to realize the constant current of described LED module;
Filter, is connected in the output of described power tube, for the output signal of described power tube is carried out to filtering;
Be connected in the error amplifier of described filter output, for the output voltage of described filter and reference voltage are compared, and comparative result amplified to output;
Pulse width modulation circuit, is connected in described error amplifier output and is connected with an oscillator, by Output rusults and the described oscillator acting in conjunction generation pwm signal of described error amplifier, for regulating the duty ratio of the switching signal of described power tube;
Current limit circuit, is connected in the output of described power tube, for limiting the peak current that flows through described LED module, adjusts the amplitude of the switching signal of described power tube;
Control circuit, described control circuit is connected in described pulse width modulation circuit and described current limit circuit, integrates duty ratio and the amplitude of the switching signal of described power tube by the signal of described pulse width modulation circuit and the output of described current limit circuit;
Drive circuit, is connected between described control circuit and the control end of described power tube, for driving the gate voltage of described power tube.
2. LED switch constant-current drive circuit according to claim 1, it is characterized in that: described voltage input module comprises an AC power and a rectification unit, described rectification unit comprises two groups of diode groups in parallel, each diode group comprises two diodes of series connection, and the two poles of the earth of described AC power are connected between two diodes of each diode group.
3. LED switch constant-current drive circuit according to claim 1, is characterized in that: the voltage of described voltage input module output is for increasing continuously or reducing continuously.
4. LED switch constant-current drive circuit according to claim 1, is characterized in that: the voltage of described voltage input module output is the commutating voltage after sinusoidal voltage rectification.
5. LED switch constant-current drive circuit according to claim 1, is characterized in that: also comprise a filter capacitor, described filter capacitor one end is connected with the output of described voltage input module, other end ground connection.
6. LED switch constant-current drive circuit according to claim 1, is characterized in that: also comprise a building-out capacitor, described building-out capacitor one end is connected with the output of described filter, and other end ground connection, for stablizing the output voltage of described filter.
7. LED switch constant-current drive circuit according to claim 1, it is characterized in that: also comprise a detection resistance, described detection resistance one end is connected with the output of described power tube, and other end ground connection, for being voltage signal by the current conversion of the described LED module of flowing through.
8. LED switch constant-current drive circuit according to claim 1, it is characterized in that: also comprise a building-out capacitor, described building-out capacitor one end is connected with the output of described error amplifier, and other end ground connection, for stablizing the output voltage of described error amplifier.
9. LED switch constant-current drive circuit according to claim 1, is characterized in that: also comprise a filter capacitor, described filter capacitor is parallel to described LED module.
10. LED switch constant-current drive circuit according to claim 1, is characterized in that: described reference voltage is default definite value or changing value.
CN201320756821.9U 2013-11-25 2013-11-25 LED switch constant current driving circuit Expired - Fee Related CN203590562U (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104661392A (en) * 2013-11-25 2015-05-27 上海莱托思电子科技有限公司 Constant-current driving circuit for LED switch
CN105722283A (en) * 2014-12-02 2016-06-29 中兴通讯股份有限公司 Current-type LCD backlight boosting method and current-type LCD backlight boosting circuit

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104661392A (en) * 2013-11-25 2015-05-27 上海莱托思电子科技有限公司 Constant-current driving circuit for LED switch
CN104661392B (en) * 2013-11-25 2017-08-25 上海莱托思电子科技有限公司 A kind of LED switch constant-current drive circuit
CN105722283A (en) * 2014-12-02 2016-06-29 中兴通讯股份有限公司 Current-type LCD backlight boosting method and current-type LCD backlight boosting circuit

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