CN101707826A - LED constant current driving circuit - Google Patents
LED constant current driving circuit Download PDFInfo
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- CN101707826A CN101707826A CN200910106078A CN200910106078A CN101707826A CN 101707826 A CN101707826 A CN 101707826A CN 200910106078 A CN200910106078 A CN 200910106078A CN 200910106078 A CN200910106078 A CN 200910106078A CN 101707826 A CN101707826 A CN 101707826A
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Abstract
The invention relates to an LED constant current driving circuit comprising LED load, a power supply, and also at least one constant current chip, a main control circuit and a switching circuit, wherein the at least one constant current chip is electrically connected with the LED load and used for conducting constant current regulation on the LED load, the main control circuit is connected with the power supply and used for conducting pulse width modulation according to input signals of the constant current chip and outputting control signals, and the switching circuit is electrically connected between the control signal outputting end of the main control circuit and the LED load. The LED constant current driving circuit has the advantages of capability of supplying adjustable constant current value, high constant current accuracy, high efficiency, high circuit reliability, simple circuit and low cost.
Description
Technical field
The present invention relates to a kind of drive circuit, more particularly, relate to a kind of LED constant-current drive circuit.
Background technology
Nowadays, LED is as light source of new generation, and range of application more and more widely.But LED needs constant drive current usually, the unstable a little flicker that will cause the light that LED sends of the electric current at its two ends.At present, low-voltage is exempted from the following dual mode of the general employing of isolated high power LED constant-current driving circuit:
One, adopts reduction voltage circuit (buck) or booster circuit (boost) or step-down and pulse width modulation controlled (PWM, Pulse Width Modulator) the LED constant-current drive circuit that boosts and combine.This mode feeds back to main control unit (MCU, Micro Controller Unit) with the signal of telecommunication of LED load output, utilizes MCU internal processes algorithm to carry out the PWM modulation then, to reach the effect of regulating electric current and constant current.Referring to Fig. 1, it is a kind of constant-current circuit of available technology adopting reduction voltage circuit, it adopts L, C, D three devices constitute the buck circuit, and by the pulse duration of PWM control switch Q output, its Current Control principle is: the signal of telecommunication that the LED load of resistance R sense collection is exported feeds back to MCU, and then carry out PWM control buck circuit, and then regulate the output constant current.But it has following critical defect: the constant current effect is undesirable, serious jitter phenomenon can appear in output current when multiplying power relation (or being bordering on the multiplying power relation) appears in sample frequency and PWM frequency, at this time also need increase a RC filter in signal sample circuit.And R, the parameter of C is selected need be according to the output current size, and PWM frequency, parameter settings such as Rsense size, when Circuits System some adjustment occurred or changes, these parameters all need reset, this has increased very big difficulty for debugging work, even and overcome the light jitter phenomenon, entire circuit can not be controlled constant current accurately, this circuit when just bringing into operation and the constant current value of work one after as a child error about 10% can appear.
Two: adopt special-purpose LDO constant current analog chip to simulate regulation and control.But the special chip of every kind of model all has fixing input voltage range and output current scope, and it is occurring under the higher situation of short circuit and input voltage, chip easily generates heat, even occur being burnt phenomenon, and size of current fixes, and can't regulate the Constant Electric Current flow valuve of output.
Summary of the invention
The technical problem to be solved in the present invention is, at the unfavorable defective of constant current effect of the above-mentioned constant-current circuit of prior art, provides a kind of constant current accuracy height, constant current value is adjustable, reliability is high and circuit is simple, cost is low LED constant-current drive circuit.
The technical solution adopted for the present invention to solve the technical problems is: construct a kind of LED constant-current drive circuit, comprise LED load and power supply, comprise that also with LED load being used for of being electrically connected at least one constant current chip of constant flow regulation, being used for of linking to each other with described power supply being carried out in the LED load carries out the governor circuit of pulse-width modulation and output control signal and be connected electrically in the control signal output ends of described governor circuit and the switching circuit between the LED load according to the input signal of constant current chip.
In LED constant-current drive circuit of the present invention, described governor circuit comprises main control unit MCU and the voltage-reference that is used for providing reference voltage to MCU that links to each other with described MCU, and the input of described each constant current chip links to each other with the signal sampling end of MCU.
In LED constant-current drive circuit of the present invention, described constant current chip is connected with described LED load.
In LED constant-current drive circuit of the present invention, the input of described constant current chip links to each other with the negative electrode of described LED load, feed back to MCU with the signal of telecommunication that LED is flowed out, the power end of described constant current chip links to each other with the output of described switching circuit and the anode of LED load simultaneously.
In LED constant-current drive circuit of the present invention, described switching circuit comprises switching tube, and described switching tube is field effect transistor or thyristor or relay.
In LED constant-current drive circuit of the present invention, described switching tube is a field effect transistor.
In LED constant-current drive circuit of the present invention, described MCU is HT46R47.
In LED constant-current drive circuit of the present invention, the 7th pin of described MCU connects the negative electrode of LED load, and its 5th pin connects the 3rd pin of voltage-reference by resistance R 5, and its 8th pin connects the 1st pin of voltage-reference, and its 10th pin connects the grid of field effect transistor.
In LED constant-current drive circuit of the present invention, described voltage-reference is the TL431 chip.
In LED constant-current drive circuit of the present invention, described constant current chip is QX7135.
Implement a kind of LED constant-current drive circuit of the present invention; have following beneficial effect: it gives MCU by the constant current chip with the electrical signal collection of LED load; carry out the break-make of pulse-width modulation and control switch circuit according to the signal of telecommunication by the program of MCU; and constant current chip and governor circuit can be regulated the constant current value in the LED load; make the present invention can provide precision high constant current; and constant current value is simply adjustable; in addition; the constant current chip is sent the signal of telecommunication of LED load into governor circuit can carry out short circuit; open circuit; and overcurrent protection; improved the reliability of circuit; and; entire circuit is simple, and cost is low.
Description of drawings
The invention will be further described below in conjunction with drawings and Examples, in the accompanying drawing:
Fig. 1 is the circuit theory diagrams that available technology adopting step-down mode is carried out constant current control;
Fig. 2 is a schematic block circuit diagram of the present invention;
Fig. 3 is the circuit theory diagrams that the present invention adopts a preferred embodiment of a constant current chip;
Fig. 4 is the circuit diagram that the present invention adopts a preferred embodiment of a constant current chip;
Fig. 5 is the circuit theory diagrams that the present invention adopts an embodiment of a plurality of constant current chips.
Embodiment
The present invention utilizes the constant current chip that the output signal of telecommunication of load is sampled MCU, by MCU control constant current chip, carries out constant current accurately control and circuit protection again.
Referring to Fig. 2; it has shown out theory diagram of the present invention. and LED constant-current drive circuit provided by the invention comprises: power supply 1; governor circuit 2; switching circuit 3; LED load 4; and constant current chip 5. constant current chips 5 are connected with LED load 4; the input of constant current chip 5 links to each other with the negative electrode of LED load 4. and governor circuit 2 links to each other with power supply 1; governor circuit 2 comprises MCU and the voltage-reference that is used for providing reference voltage to MCU that links to each other with described MCU; the signal sampling end of MCU links to each other with the negative electrode of LED load; thereby the reference voltage that sampling the signal of telecommunication .MCU that flows out from the LED load provides this signal of telecommunication and reference voltage source again compares to export control signal entire circuit is handled; for example change the width ratio of the high-low level of the MCU output signal of telecommunication; the break-make of output signal control switch. switching circuit 3 is connected between the control signal output ends and LED load 4 of governor circuit 2; switching circuit 3 changes the disconnection and closed state of switch according to the output signal of MCU. and switching circuit 3 can be field effect transistor or thyristor or relay; or other can realize the components and parts of the conversion of conducting and disconnection. owing to be preferably the response speed of switch comparatively fast with protective circuit herein; so preferably, switch is a field effect transistor in the switching circuit 3.
Fig. 4 is the circuit diagram that the present invention adopts a preferred embodiment of a constant current chip 5.In Fig. 6, governor circuit 2 comprise MCU, link to each other with MCU with voltage-reference that fixing 2.5V voltage is provided, and resistance R 1, R2, R5, capacitor C 1, C2, C3, switch S 1.MCU can adopt the single-chip microcomputer of two above A/D mouths of 8 bit strips, for example atiny18 single-chip microcomputer of HT46R47, AVR etc.Single-chip microcomputer needs the signal of telecommunication of a voltage-reference relatively to collect from the LED load, and preferably, voltage-reference adopts TL431.The pin 3 of voltage-reference links to each other with the pin 5 of MCU by current-limiting resistance R5, and its pin 1 connects the pin 8 of MCU.Pin 9 ground connection of MCU, its pin 11 is by filter capacitor C2 ground connection, its pin 12 is by while connecting resistance R1 between filter capacitor C1 ground connection, pin 12 and the capacitor C 2, its pin 13 is by current-limiting resistance R2 ground connection, its pin 10 links to each other with the grid of field effect transistor in the switching circuit with the output control signal by resistance R 4, its signal sampling end, promptly pin 7 connects the negative electrode of LED load, is connected between the pin 2 and ground of MCU after filter capacitor C3 and switch S 1 are in parallel.In the present embodiment, the preferred P-channel field-effect transistor (PEFT) pipe of switch, for example Irml6401 in the switching circuit.The constant current chip can adopt for example QX7135 series, and this circuit adopts sb42351a, and the normal value of its constant current is 335mA.The signal of telecommunication that the signal input pin 1 of constant current chip flows out the LED load feeds back to the signal sampling end of MCU in the control circuit, the described signal of telecommunication is preferably voltage signal, in governor circuit, voltage signal is than the easier realization control of current signal, and the better effects if of control.The control circuit root compares the voltage signal that collects and the voltage of voltage-reference, and then can judge entire circuit whether problem is arranged, and then protects, and the physical circuit protection philosophy will be described below.In governor circuit, because the control signal output ends of MCU links to each other with switching circuit, close the PWM function of the PD0 mouth of MCU, make it be made as common I/O mouth, can change level to realize the effect of pulse-width modulation by the MCU plug-in, the conducting and the disconnection of switch in the output of MCU and then the control switch circuit, thereby can control the different constant current value of output.In the present embodiment, can select corresponding different programs with the different constant current value of control output by switch S 1.
Operation principle of the present invention is elaborated in conjunction with Fig. 3 and Fig. 4:
The normal value of constant current of supposing the constant current chip is I, utilizes the width ratio of MCU output high-low level, directly the service time Ton of control switch pipe Q and turn-off time Toff, and then output current is that adjustable constant-flow is exported Iout=I * [Ton/ (Ton+Toff)]; Therefore LED can obtain the adjustable constant-flow value adapting to illumination or the decoration demand of people to different brightness, and the constant current accuracy height.
In Fig. 3, because constant current chip IC 1 is a power consumption formula analog chip,, then may cause heating in case its work pressure drop is too high, even situation about being damaged.MCU of the present invention samples to pressure drop signal from the input input of IC1, carry out programmed algorithm in MCU inside, get the repeatedly mean value of sampling, at MCU inner setting one pressure drop limiting value Vlg, in case detecting the pressure drop signal sample mean, MCU is higher than Vlg, then export control signal with cut-off switch Q1 to cut off circuit, the time that perhaps shortens Ton is with the effective pressure drop of balance.
Constant-current circuit reliability height of the present invention can carry out short circuit, open circuit, reaches overcurrent protection, and the principle when the supposition switch is the P-channel field-effect transistor (PEFT) pipe is as follows:
When LED opens circuit; MCU is 0 at the voltage signal that the input of constant current chip 5 samples; can set field effect transistor disconnection in the MCU output high level control switch circuit 3 this moment; thereby cut off circuit with protective circuit; as malfunction indicator lamp is arranged in the fruit product, can also draw malfunction indicator lamp from MCU and carry out the fault prompting.
When the LED short circuit; MCU is supply voltage Vin at the voltage signal that the input of constant current chip 5 samples; if this moment is shut-off circuit not; to cause burning of constant current chip 5, even damage MCU, so the short-circuit protection of LED is very important; it judges that with open circuit fault principle is identical; it is higher unusually at first to sample the input voltage signal that the input of constant current chip 5 sends by MCU, and MCU output control signal is cut off circuit with control switch circuit 3, and then improves the reliability of circuit.
When the LED overcurrent, collect the input voltage signal Vout output abnormality that the input of constant current chip 5 sends by MCU, MCU can adjust the time of Ton, to reduce effective pressure drop Vreal=Vout * [Ton/ (Ton+Toff)].
Because LED is normally by low-voltage driving, and the minor variations of voltage all can cause the very large variation of LED two ends electric current, so power supply 1 of the present invention adopts low tension, preferably, the present invention adopts low-voltage direct, baby battery for example, therefore, circuit of the present invention can so also can be simplified circuit in order to avoid isolate.
Referring to Fig. 5, the circuit theory diagrams of its embodiment of a plurality of constant current chips for the present invention adopts.When the current value of circuit needs surpasses the maximum constant current value of single constant current chip 5, can carry out mode as Fig. 5, to connect with the LED load after a plurality of constant current chip 5 parallel connections to enlarge electric current, control principle is identical with above-mentioned single constant current chip, does not repeat them here again.
The above only is the preferred embodiments of the present invention, not in order to restriction the present invention, all any modifications of being done in the spirit and principles in the present invention, is equal to and replaces or improvement etc., all should be included in protection scope of the present invention.
Claims (10)
1. LED constant-current drive circuit, comprise LED load and power supply, it is characterized in that, comprise that also with LED load being used for of being electrically connected at least one constant current chip of constant flow regulation, being used for of linking to each other with described power supply being carried out in the LED load carries out the governor circuit of pulse-width modulation and output control signal and be connected electrically in the control signal output ends of described governor circuit and the switching circuit between the LED load according to the input signal of described constant current chip.
2. LED constant-current drive circuit according to claim 1, it is characterized in that, described governor circuit comprises main control unit MCU and the voltage-reference that is used for providing reference voltage to MCU that links to each other with described MCU, and the input of described each constant current chip links to each other with the signal sampling end of MCU.
3. LED constant-current drive circuit according to claim 1 is characterized in that, described constant current chip is connected with described LED load.
4. according to claim 1 or 3 described LED constant-current drive circuits, it is characterized in that, the input of described constant current chip links to each other with the negative electrode of described LED load, feed back to MCU with the signal of telecommunication that LED is flowed out, the power end of described constant current chip links to each other with the output of described switching circuit and the anode of LED load simultaneously.
5. LED constant-current drive circuit according to claim 1 is characterized in that described switching circuit comprises switching tube, and described switching tube is field effect transistor or thyristor or relay.
6. LED constant-current drive circuit according to claim 5 is characterized in that, described switching tube is a field effect transistor.
7. LED constant-current drive circuit according to claim 1 is characterized in that, described MCU is HT46R47.
8. according to claim 6 or 7 described LED constant-current drive circuits, it is characterized in that, (7) pin of described MCU connects the negative electrode of LED load, its (5) pin connects (3) pin of voltage-reference by resistance R 5, its (8) pin connects (1) pin of voltage-reference, and its (10) pin connects the grid of field effect transistor.
9. LED constant-current drive circuit according to claim 1 is characterized in that, described voltage-reference is the TL431 chip.
10. LED constant-current drive circuit according to claim 1 is characterized in that, described constant current chip is QX7135.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101060780A CN101707826B (en) | 2009-03-19 | 2009-03-19 | LED constant current driving circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009101060780A CN101707826B (en) | 2009-03-19 | 2009-03-19 | LED constant current driving circuit |
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| CN101707826A true CN101707826A (en) | 2010-05-12 |
| CN101707826B CN101707826B (en) | 2012-12-19 |
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| CN2009101060780A Expired - Fee Related CN101707826B (en) | 2009-03-19 | 2009-03-19 | LED constant current driving circuit |
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Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101815388A (en) * | 2010-05-31 | 2010-08-25 | 海洋王照明科技股份有限公司 | Led lamp control circuit and led lamp |
| CN102291875A (en) * | 2011-05-05 | 2011-12-21 | 杨敏 | DSP (digital signal processor)/digital signal processor-based high-side driving LED (light-emitting diode) constant-current source circuit |
| CN102695319A (en) * | 2011-03-23 | 2012-09-26 | 海洋王照明科技股份有限公司 | LED stepless light regulating circuit |
| CN102695320A (en) * | 2011-03-24 | 2012-09-26 | 海洋王照明科技股份有限公司 | Constant current drive circuit |
| CN102711307A (en) * | 2011-03-28 | 2012-10-03 | 海洋王照明科技股份有限公司 | Dimmable light-emitting diode (LED) drive circuit and lamp |
| CN103517498A (en) * | 2012-06-26 | 2014-01-15 | 海洋王照明科技股份有限公司 | Intelligent temperature-controlled light-modulation control circuit of LED electric torch |
| CN103619097A (en) * | 2013-11-21 | 2014-03-05 | 江门市三泰照明制品有限公司 | Wirelessly-controlled LED lamp |
| CN103648216A (en) * | 2013-12-06 | 2014-03-19 | 武汉精立电子技术有限公司 | Intelligent constant-current high-power LED driving method |
| CN104780681A (en) * | 2015-04-10 | 2015-07-15 | 常州市赛尔交通器材有限公司 | Lighting feedback system for headlamps for railway vehicles |
| CN106304556A (en) * | 2016-08-25 | 2017-01-04 | 上海传英信息技术有限公司 | Current control circuit and current control method |
| CN106328072A (en) * | 2016-10-27 | 2017-01-11 | 刘勇 | Backlight intensity circuit and display device thereof |
| CN113473675A (en) * | 2021-06-03 | 2021-10-01 | 荣耀终端有限公司 | Light source circuit and terminal |
| CN114420057A (en) * | 2021-12-28 | 2022-04-29 | 荣耀终端有限公司 | Backlight power supply, display device and electronic equipment |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101227778B (en) * | 2008-02-19 | 2011-12-14 | 东南大学 | Self-excited oscillation type high power LED constant-current driving circuit |
| CN101370335A (en) * | 2008-09-27 | 2009-02-18 | 易际平 | Driving circuit for LED illumination |
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2009
- 2009-03-19 CN CN2009101060780A patent/CN101707826B/en not_active Expired - Fee Related
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101815388A (en) * | 2010-05-31 | 2010-08-25 | 海洋王照明科技股份有限公司 | Led lamp control circuit and led lamp |
| CN102695319B (en) * | 2011-03-23 | 2014-12-17 | 海洋王照明科技股份有限公司 | LED stepless light regulating circuit |
| CN102695319A (en) * | 2011-03-23 | 2012-09-26 | 海洋王照明科技股份有限公司 | LED stepless light regulating circuit |
| CN102695320B (en) * | 2011-03-24 | 2015-11-11 | 海洋王照明科技股份有限公司 | Constant-current drive circuit |
| CN102695320A (en) * | 2011-03-24 | 2012-09-26 | 海洋王照明科技股份有限公司 | Constant current drive circuit |
| CN102711307A (en) * | 2011-03-28 | 2012-10-03 | 海洋王照明科技股份有限公司 | Dimmable light-emitting diode (LED) drive circuit and lamp |
| CN102291875A (en) * | 2011-05-05 | 2011-12-21 | 杨敏 | DSP (digital signal processor)/digital signal processor-based high-side driving LED (light-emitting diode) constant-current source circuit |
| CN103517498A (en) * | 2012-06-26 | 2014-01-15 | 海洋王照明科技股份有限公司 | Intelligent temperature-controlled light-modulation control circuit of LED electric torch |
| CN103619097A (en) * | 2013-11-21 | 2014-03-05 | 江门市三泰照明制品有限公司 | Wirelessly-controlled LED lamp |
| CN103648216A (en) * | 2013-12-06 | 2014-03-19 | 武汉精立电子技术有限公司 | Intelligent constant-current high-power LED driving method |
| CN104780681A (en) * | 2015-04-10 | 2015-07-15 | 常州市赛尔交通器材有限公司 | Lighting feedback system for headlamps for railway vehicles |
| CN104780681B (en) * | 2015-04-10 | 2018-03-13 | 常州市赛尔交通器材有限公司 | Headlamp lighting reponse system for rail vehicle |
| CN106304556A (en) * | 2016-08-25 | 2017-01-04 | 上海传英信息技术有限公司 | Current control circuit and current control method |
| CN106328072A (en) * | 2016-10-27 | 2017-01-11 | 刘勇 | Backlight intensity circuit and display device thereof |
| CN113473675A (en) * | 2021-06-03 | 2021-10-01 | 荣耀终端有限公司 | Light source circuit and terminal |
| CN114420057A (en) * | 2021-12-28 | 2022-04-29 | 荣耀终端有限公司 | Backlight power supply, display device and electronic equipment |
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| CN101707826B (en) | 2012-12-19 |
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Granted publication date: 20121219 Termination date: 20190319 |