CN101925217B - LED constant current driving circuit - Google Patents
LED constant current driving circuit Download PDFInfo
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- CN101925217B CN101925217B CN2009101079664A CN200910107966A CN101925217B CN 101925217 B CN101925217 B CN 101925217B CN 2009101079664 A CN2009101079664 A CN 2009101079664A CN 200910107966 A CN200910107966 A CN 200910107966A CN 101925217 B CN101925217 B CN 101925217B
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Abstract
The invention relates to an LED constant current driving circuit. The constant current driving circuit comprises a driving chip, a load LED and a feedback loop, wherein the feedback loop comprises a first resistor which is connected between a negative electrode of the load LED and the ground and also comprises a second resistor, a third resistor and a stabilized voltage source; a voltage output end of the stabilized voltage source is connected with the negative electrode of the load LED through the second resistor and the third resistor which are connected in series in turn; the crossing point of the second resistor and the third resistor is connected with a feedback end of the driving chip; the resistance of the second resistor and the resistance of the third resistor are 100 times greater than the resistance of the first resistor; and the output voltage of the stabilized voltage source is greater than the voltage of the feedback end of the driving chip. By adding the second resistor, the third resistor and the stabilized voltage source into the feedback loop, circuit loss is reduced and power conversion efficiency is improved when a certain feedback voltage is ensured by using partial pressure compensation of the second resistor and the third resistor.
Description
Technical field
The present invention relates to the LED Driving technique, more particularly, relate to a kind of LED constant-current drive circuit.
Background technology
The LED constant-current drive circuit that adopts at present all is to realize with special-purpose LED drive IC.In large electric current LED used, general DC/DCIC was fed back to voltage-type (feedback voltage is generally about 1.25V or 2.5V).
Fig. 1 is the circuit theory diagrams that prior art LED constant current drives, and as shown in Figure 1, series connection one sample resistance R1 in load LED branch road directly adopts sample resistance to realize feedback.If driving the feedback voltage of chip is 1.25V, when the electric current that flows through LED was 0.7A, resistance R 1 need be got the resistance that resistance is 1.78 Europe, and then this moment, power consumption had 0.85W; If driving the feedback voltage of chip is 2.5V, when the electric current that flows through LED was 0.7A, resistance R 1 need be got the resistance that resistance is 3.57 Europe, and then this moment, power consumption had 1.75W, and therefore, for the LED constant-current drive circuit, power consumption is large, the power supply transformation efficiency is low.
Summary of the invention
The technical problem to be solved in the present invention is, the defective that the loss of above-mentioned LED constant-current drive circuit is large, the power supply transformation efficiency is low for prior art provides the LED that a kind of loss is little, the power supply transformation efficiency is high 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 and drive chip, load LED and feedback loop, feedback loop comprises the first resistance that is connected between load LED negative pole and the ground, it is characterized in that, feedback loop also comprises the second resistance, three resistance and source of stable pressure; The voltage output end of described source of stable pressure is by the second resistance of successively series connection, the negative pole that three resistance connect load LED, and the joint of the second resistance, three resistance connects the feedback end that drives chip; The resistance of described the second resistance, three resistance is greater than 100 times of the first resistance; The output voltage of source of stable pressure is greater than the feedback end voltage that drives chip.
In LED constant-current drive circuit of the present invention, also comprise being connected to the 4th resistance that drives between chip voltage output and the source of stable pressure voltage input end, the output voltage of described driving chip provides operating voltage by the 4th resistance for source of stable pressure.
In LED constant-current drive circuit of the present invention, described source of stable pressure is that model is the chip of TL431, the plus earth of described chip TL431, and its negative electrode and reference edge connect the voltage output end that drives chip by the 4th resistance.
In LED constant-current drive circuit of the present invention, the second resistance is adjustable resistance.
In LED constant-current drive circuit of the present invention, the 3rd resistance is adjustable resistance.
In LED constant-current drive circuit of the present invention, the resistance of described the second resistance, three resistance is greater than 1,000 times of the first resistance.
In LED constant-current drive circuit of the present invention, also comprise the negative electrode that is connected in parallel on source of stable pressure and the first electric capacity between the anode, described the first electric capacity is used for the short-circuit protection of source of stable pressure.
In LED constant-current drive circuit of the present invention, described driving chip be feedback voltage greater than 0.6V integrated chip.
In LED constant-current drive circuit of the present invention, also comprise the second resistance, the 3rd electric capacity and the 5th resistance, described the second electric capacity and the 5th resistance are connected afterwards and the 3rd Capacitance parallel connection, one end connects the 8th pin that drives chip, the other end connects the 9th pin that drives chip, and described the second electric capacity, the 3rd electric capacity and the 5th resistance are used for the phase compensation of feedback voltage.
In LED constant-current drive circuit of the present invention, also comprise the first field effect transistor and the second field effect transistor, the drain electrode of the first field effect transistor connects outside direct current, its grid connects the 19th pin that drives chip, its source electrode connects the drain electrode of the second field effect transistor, the grid of the second field effect transistor connects the 15th pin that drives chip, its source ground drives chip and alternately exports the alternate conduction that high level is realized the first field effect transistor, the second field effect transistor according to its 19th pin of signal controlling and the 15th pin of feedback loop.
Implement LED constant-current drive circuit of the present invention, by in feedback loop, having added the second resistance, the 3rd resistance and source of stable pressure, and correspondingly reduce the resistance of the first resistance, utilize the dividing potential drop compensation of the second resistance, the 3rd resistance, guaranteeing feedback voltage one regularly, reduce the loss of circuit, improved the transformation efficiency of power supply; In addition, can realize the output of LED constant-current drive circuit wide-range voltage by the resistance of regulating the second resistance, the 3rd resistance.
Description of drawings
The invention will be further described below in conjunction with drawings and Examples, in the accompanying drawing:
Fig. 1 is the schematic diagram of prior art LED constant-current drive circuit;
Fig. 2 is the schematic diagram of LED constant-current drive circuit of the present invention;
Fig. 3 is the circuit diagram of LED constant-current drive circuit preferred embodiment of the present invention.
Embodiment
Fig. 2 is the schematic diagram of LED constant-current drive circuit of the present invention, and this drive circuit comprises load LED, drives chip and feedback loop.Described feedback loop comprises resistance R 1, R2, R6 and source of stable pressure.The voltage output end of source of stable pressure is by resistance R 6, R2, the R1 ground connection of successively series connection, the joint of resistance R 1, R2 connects the negative pole of load LED, the joint of resistance R 2, R6 connects the feedback end (FB) that drives chip, and greater than 100 times of resistance R 1 resistance, the output voltage of source of stable pressure is greater than the feedback end voltage that drives chip at least for the resistance of resistance R 2, R6.
In Fig. 2, guaranteeing feedback voltage and flowing through in the certain situation of the electric current of load LED, reduce the loss power of circuit, namely put the voltage V of A
AAnd I
LEDOne regularly, and the voltage V of some A
A=V
1+ V
2, electric current I
1=I
LED+ I
2, reduce the loss power P of circuit
s=P
1+ P
2+ P
6, (wherein, V
1Be the voltage of resistance R 1, V
2Be the voltage of resistance R 2, wherein P
1Be the power of resistance R 1, P
2Be the power of resistance R 2, P
6Be the power of resistance R 6, I
LEDThe electric current that load LED flows through, I
2The electric current by resistance R 2, R6, R
1Be the resistance of resistance R 1, R
2Be the resistance of resistance R 2, R
6Resistance for resistance R 6).When the resistance of resistance R 2, R6 was far longer than the resistance of resistance R 1, for example the resistance of resistance R 2, R6 was respectively a kilohm level, and the resistance of resistance R 1 is ohm level, and the output voltage of source of stable pressure is V
Out, V
OutCan be the direct voltage in the 0-36V scope, so the electric current I of resistance R 2, R6
2Be milliampere level, electric current I
2Compare the electric current I of load LED
LEDCan ignore, so the loss power P of resistance R 2, R6
2, P
6Very little, can be similar to and ignore; In addition, because electric current I
2Can ignore, so the electric current I of resistance R 1
1Equal the electric current I of LED
LED, at this moment, the resistance of resistance R 1 can be expressed as formula: R
1=(V
A-(V
Out-V
A) R
2/ R
6)/I
LED, again because the output voltage of source of stable pressure greater than the feedback voltage that drives chip, i.e. V
OutV
A, (V in the formula
Out-V
A) R
2/ R
60, so the resistance of the resistance R 1 in the technical solution of the present invention is less than the resistance (V of resistance R in the prior art 1
FB/ I
LED), hence one can see that, and the loss power of resistance R 1 is far smaller than the loss power of R1 in the prior art, and then the loss power of whole circuit is very little.Table 1 is the circuit loss contrast table among prior art Fig. 1 and technical solution of the present invention Fig. 2.
Table 1
Preferably, resistance R 2 is adjustable resistance, by the resistance R of regulating resistance R2
2, regulate R
2, R
6Ratio, perhaps resistance R 6 is adjustable resistance, perhaps resistance R 2, R6 both be adjustable resistance simultaneously, the present invention is not limited to this, be intended to the ratio of regulating resistance R2, R6 resistance, thereby regulate the output current of constant-current drive circuit, realize the output of LED constant-current drive circuit wide-range voltage.In technical scheme of the present invention, flow through the electric current I of LED
LED=(V
A-(V
Out-V
A) R
2/ R
6)/R
1, therefore, in the source of stable pressure output voltage V
Out, feedback voltage V
A, resistance R 1 resistance R
1One regularly, regulates R
2, R
6The electric current of ratio adjustable throttle overload LED.Table 2 is the resistance ratio of resistance R 2, R6 and the relation table of load LED electric current.
Table 2
Fig. 3 shows the circuit theory diagrams of LED constant-current drive circuit preferred embodiment of the present invention; in the present embodiment; driving chip is that model is the integrated chip U4 of LM5116; source of stable pressure is that model is the integrated chip U1 of TL431; also comprise resistance R 7; R3; R4; R5; capacitor C 1; C2; C5; C6; field effect transistor Q2; Q9; inductance L 1; the negative electrode of source of stable pressure U1 and reference edge connect the positive pole of load LED by resistance R 7, its plus earth, and capacitor C 6 is connected in parallel between the anode and negative electrode of source of stable pressure U1; for source of stable pressure provides operating voltage, capacitor C 6 is used for the short-circuit protection of source of stable pressure U1 to the output voltage of driving chip U4 by resistance R 7.The negative electrode of source of stable pressure U1 and reference edge are by resistance R 6, R2, the R1 ground connection of successively series connection, the joint of resistance R 1, R2 connects the negative pole of load LED, the joint of resistance R 6, R2 connects the 8th pin (FB) that drives chip U4, in parallel with capacitor C 2 after capacitor C 1 and resistance R 3 series connection, one end connects the 8th pin (FB) that drives chip U4, the other end connects the 9th pin (COM) that drives chip, and capacitor C 1, C2, resistance R 3 are used for the phase compensation of feedback voltage.The reference edge of source of stable pressure U1 is connected with negative electrode, therefore exports the direct current of voltage regulation of 2.5V, and the feedback voltage that drives chip U4 is 1.25V, if get R
1Be 0.53 Ω, R
2Be 22k Ω, R
6Be 30k Ω, so the electric current I of resistance R 2
2Electric current be 0.04mA, the power of resistance R 2, R6 is very little, can ignore, and the voltage at resistance R 2 two ends is 0.88V, the voltage of therefore putting B is 0.37V, therefore, when the resistance of resistance R 1 is 0.53 Ω, can realize that the constant current of load LED 0.7A drives, and this moment, the loss of circuit is about 0.19W, is far smaller than the circuit loss that direct employing sample resistance is realized feedback.
The 19th pin (HO) that drives chip U4 connects the grid of field effect transistor Q2, the drain electrode of field effect transistor Q2 connects outside direct current (not shown), its source class connects the drain electrode of field effect transistor Q9, the grid of field effect transistor connects the 15th pin (LO) that drives chip, its source class ground connection, resistance R 4 is connected between the grid and source electrode of field effect transistor Q2, resistance R 5 is connected between the grid and source electrode of field effect transistor Q9, the drain electrode of one termination field effect transistor Q9 of inductance L 1, its other end connects the positive pole of load LED, and capacitor C 5 is connected between the positive pole and ground of load LED.Drive chip U4 adjusts output voltage according to the feedback voltage signal of feedback loop duty ratio, to reach the purpose of adjusting the output voltage size, concrete as, when driving the 19th pin (HO) the output high level of chip U4, field effect transistor Q2 conducting, the output voltage that drive chip this moment is high level, when driving the 15th pin (LO) the output high level of chip U4, field effect transistor Q9 conducting, the output voltage that drive chip this moment is low level, drive the 19th pin (HO) of chip U4 and the time that the 15th pin (LO) replaces high level by adjustment, namely capable of regulating drives the output voltage of chip.Inductance L 1 and capacitor C 5 are used for the output voltage of control chip is carried out filtering.
When resistance R 2 or R6 or both were adjustable rheostat simultaneously, by the resistance ratio of regulating resistance R2 and R6, also adjustable throttle was crossed the constant current value of LED, realizes that the LED constant current of wide range output voltage drives.For example, in the above-described embodiments, when the resistance of R2 was adjusted to 11k Ω by 22k Ω, the electric current that flows through LED became 1.5A by 0.7A, had realized that like this LED constant current of wide range output voltage drives.
The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., all should be included within the claim scope of the present invention.
Claims (10)
1. a LED constant-current drive circuit comprises driving chip, load LED and feedback loop, and feedback loop comprises the first resistance that is connected between load LED negative pole and the ground, it is characterized in that, feedback loop also comprises the second resistance, the 3rd resistance and source of stable pressure;
The voltage output end of described source of stable pressure is by the second resistance of successively series connection, the negative pole that the 3rd resistance connects load LED, and the joint of the second resistance, the 3rd resistance connects the feedback end that drives chip;
The resistance of described the second resistance, the 3rd resistance is greater than 100 times of the first resistance;
The output voltage of source of stable pressure is greater than the feedback end voltage that drives chip.
2. LED constant-current drive circuit according to claim 1, it is characterized in that, also comprise being connected to the 4th resistance that drives between chip voltage output and the source of stable pressure voltage input end, the output voltage of described driving chip provides operating voltage by the 4th resistance for source of stable pressure.
3. LED constant-current drive circuit according to claim 2 is characterized in that, described source of stable pressure is that model is the chip of TL431, the plus earth of described chip TL431, and its negative electrode and reference edge connect the voltage output end that drives chip by the 4th resistance.
4. LED constant-current drive circuit according to claim 1 is characterized in that, the second resistance is adjustable resistance.
5. LED constant-current drive circuit according to claim 1 is characterized in that, the 3rd resistance is adjustable resistance.
6. LED constant-current drive circuit according to claim 1 is characterized in that, the resistance of described the second resistance, the 3rd resistance is greater than 1,000 times of the first resistance.
7. LED constant-current drive circuit according to claim 3 is characterized in that, also comprises the negative electrode that is connected in parallel on source of stable pressure and the first electric capacity between the anode, and described the first electric capacity is used for the short-circuit protection of source of stable pressure.
8. LED constant-current drive circuit according to claim 1 is characterized in that, described driving chip is that feedback voltage is greater than the integrated chip of 0.6V.
9. LED constant-current drive circuit according to claim 8, it is characterized in that, also comprise the second electric capacity, the 3rd electric capacity and the 5th resistance, described the second electric capacity and the 5th resistance are connected afterwards and the 3rd Capacitance parallel connection, one end connects the 8th pin that drives chip, and the other end connects the 9th pin that drives chip, and described second and third electric capacity and the 5th resistance are used for the phase compensation of feedback voltage, wherein, described driving chip is that model is the chip of LM5116.
10. LED constant-current drive circuit according to claim 8, it is characterized in that, also comprise the first field effect transistor and the second field effect transistor, the drain electrode of the first field effect transistor connects outside direct current, its grid connects the 19th pin that drives chip, its source electrode connects the drain electrode of the second field effect transistor, the grid of the second field effect transistor connects the 15th pin that drives chip, its source ground, driving chip alternately exports high level according to its 19th pin of signal controlling of feedback loop and the 15th pin and realizes the first field effect transistor, the alternate conduction of the second field effect transistor, wherein, described driving chip is that model is the chip of LM5116.
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|---|---|---|---|
| CN2009101079664A CN101925217B (en) | 2009-06-12 | 2009-06-12 | LED constant current driving circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101079664A CN101925217B (en) | 2009-06-12 | 2009-06-12 | LED constant current driving circuit |
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| CN101925217A CN101925217A (en) | 2010-12-22 |
| CN101925217B true CN101925217B (en) | 2013-04-24 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103634990A (en) * | 2013-12-04 | 2014-03-12 | 中航华东光电有限公司 | LED constant-current source circuit with onboard 80V surge resistance and dynamic compensation functions |
| CN107197569A (en) * | 2017-07-25 | 2017-09-22 | 合肥惠科金扬科技有限公司 | A kind of LED backlight Drive Protecting Circuit and display device |
| CN110445395A (en) * | 2019-08-13 | 2019-11-12 | 苏州格远电气有限公司 | Wide-voltage range direct current input switch power supply |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN200987226Y (en) * | 2006-12-25 | 2007-12-05 | 陆晓元 | Large power LED driving module device |
| CN101212850A (en) * | 2006-12-29 | 2008-07-02 | 上海贝岭股份有限公司 | Pulsed driven LED lighting circuit |
| CN201127137Y (en) * | 2007-12-17 | 2008-10-01 | 宁波市鄞州威迪电子有限公司 | High-power LED drive circuit |
| CN201252662Y (en) * | 2008-05-09 | 2009-06-03 | 深圳市东辰科技有限公司 | Constant current drive circuit for realizing high brightness LED lamp through utilizing switch power supply chip |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005080353A (en) * | 2003-08-29 | 2005-03-24 | Toyoda Gosei Co Ltd | Power supply device for led |
| JP2007299928A (en) * | 2006-04-28 | 2007-11-15 | Mirai Kankyo Kaihatsu Kenkyusho Kk | Constant current driving circuit for light emitting diode |
-
2009
- 2009-06-12 CN CN2009101079664A patent/CN101925217B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN200987226Y (en) * | 2006-12-25 | 2007-12-05 | 陆晓元 | Large power LED driving module device |
| CN101212850A (en) * | 2006-12-29 | 2008-07-02 | 上海贝岭股份有限公司 | Pulsed driven LED lighting circuit |
| CN201127137Y (en) * | 2007-12-17 | 2008-10-01 | 宁波市鄞州威迪电子有限公司 | High-power LED drive circuit |
| CN201252662Y (en) * | 2008-05-09 | 2009-06-03 | 深圳市东辰科技有限公司 | Constant current drive circuit for realizing high brightness LED lamp through utilizing switch power supply chip |
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|---|---|
| CN101925217A (en) | 2010-12-22 |
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