CN204362375U - A kind of LED drive circuit - Google Patents
A kind of LED drive circuit Download PDFInfo
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- CN204362375U CN204362375U CN201420865364.1U CN201420865364U CN204362375U CN 204362375 U CN204362375 U CN 204362375U CN 201420865364 U CN201420865364 U CN 201420865364U CN 204362375 U CN204362375 U CN 204362375U
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- error amplifying
- electric capacity
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
Abstract
The utility model discloses a kind of LED drive circuit, comprise LED group circuit, error amplifying circuit, source voltage control circuit, reference voltage source and closed loop connecting circuit; Source voltage control circuit connects described LED group circuit; First voltage signal inputs of error amplifying circuit and LED group circuit; Second voltage signal inputs of error amplifying circuit is connected with reference voltage source; The signal output part of error amplifying circuit is connected with source voltage control circuit; Described closed loop connecting circuit connects the output of described source voltage control circuit and the first voltage signal inputs of described error amplifying circuit.Implement to produce voltage overshoot phenomenon, protection LED when the utility model can realize LED constant current control and prevent power initiation, ensure that hardware cost is low simultaneously.
Description
Technical field
The utility model relates to LED technology field, is specifically related to a kind of LED drive circuit.
Background technology
LED, i.e. light-emitting diode, possess nonlinear voltage-current characteristic and negative temperature coefficient.Owing to possessing nonlinear voltage-current characteristic, if adopt drive of constant voltage source, so when constant pressure source is stablized not, produce fluctuation, the curent change that LED is larger will be caused, cause LED luminosity unstable, even burn LED.Owing to possessing negative temperature coefficient, if adopt drive of constant voltage source, when temperature increases, its electric current will increase, and its brightness does not increase.Electric current increases only can make its temperature rise higher, will increase light decay like this, reduce the life-span.In like manner, if adopt drive of constant voltage source, when falling at temperature, its electric current will decline, and causes luminosity to decline.Thus, LED drives and generally adopts constant-current source.
Constant current driving is the sampled voltage by gathering LED, forms the size that closed loop adjusts supply power voltage, makes the current stabilization by LED.But because LED itself has cut-in voltage, when supply voltage just starts, be not enough to make LED conducting, thus the sampled voltage of LED exports is zero, causes LED drive circuit open loop.Thus do not controlled in the zooming process of supply voltage, occur the phenomenon exporting overshoot, LED time serious, may be caused to burn.
Utility model content
The purpose of this utility model is to overcome the deficiencies in the prior art, provides a kind of LED drive circuit, can realize LED constant current and controls and prevent from producing voltage overshoot phenomenon during power initiation, protection LED.
In order to achieve the above object, the utility model embodiment is by the following technical solutions:
A kind of LED drive circuit, comprises LED group circuit, error amplifying circuit, source voltage control circuit, reference voltage source, the first resistance, the second resistance and the first electric capacity;
The output of described source voltage control circuit connects the power end of described LED group circuit;
First voltage signal inputs of described error amplifying circuit is connected with the signals collecting end of described LED group circuit; Second voltage signal inputs of described error amplifying circuit is connected with described reference voltage source; The signal output part of described error amplifying circuit is connected with the input of described source voltage control circuit;
Described closed loop connecting circuit connects the output of described source voltage control circuit and the first voltage signal inputs of described error amplifying circuit.
Further, described closed loop connecting circuit comprises the first resistance, the second resistance and the first electric capacity;
The first end of described first resistance connects the output of described source voltage control circuit;
The first end of described second resistance connects the second end of described first resistance, and the second end ground connection of described second resistance;
The first end of described first electric capacity connects the second end of described first resistance, and the second end of described first electric capacity connects the first voltage signal inputs of described error amplifying circuit.
Further, described LED group circuit comprises N number of LED and sampling resistor of connecting successively, N >=1; Wherein, the power end of the just very described LED group circuit of first LED; The negative pole of N number of LED is connected with the first end of described sampling resistor, the second end ground connection of described sampling resistor; The first end of described sampling resistor is the signals collecting end of described LED group circuit.
Further, described error amplifying circuit comprises operational amplifier, the 3rd resistance, the second electric capacity and the 3rd electric capacity; The normal phase input end of described operational amplifier is the second voltage signal inputs of described error amplifying circuit, the inverting input of described operational amplifier is the first voltage signal inputs of described error amplifying circuit, and the output of described operational amplifier is the signal output part of described error amplifying circuit; The first end of described 3rd resistance connects the output of described operational amplifier, and the second end of described 3rd resistance connects the first end of described second electric capacity; Second end of described second electric capacity connects the inverting input of described operational amplifier; The first end of described 3rd electric capacity connects the output of described operational amplifier, and the second end of described 3rd electric capacity connects the inverting input of described operational amplifier.
Further, described LED drive circuit also comprises bleeder circuit; Described reference voltage source is connected to the second voltage signal inputs of described error amplifying circuit by described bleeder circuit.
Further, described bleeder circuit comprises the 4th resistance, the 5th resistance and the 4th electric capacity; The first end of described 4th resistance connects described reference voltage source, and the second end of described 4th resistance connects the first end of described 5th resistance; The first end of described 5th resistance connects the second voltage signal inputs of described error amplifying circuit, the second end ground connection of described 5th resistance; Described 4th electric capacity and described 5th resistor coupled in parallel.
Further, described LED drive circuit also comprises RC filter circuit; The signals collecting end of described LED group circuit is connected with the first voltage signal inputs of described error amplifying circuit by described RC filter circuit.
Further, described RC filter circuit comprises the 6th resistance and the 5th electric capacity; The first end of described 6th resistance connects the signals collecting end of described LED group circuit, and the second end of described 6th resistance connects the first end of described 5th electric capacity; Second end ground connection of described 5th electric capacity; Second end of described 6th resistance connects the first voltage signal inputs of described error amplifying circuit.
Further, described LED drive circuit also comprises optical coupling isolation circuit; The signal output part of described error amplifying circuit is connected with the input of described source voltage control circuit by described optical coupling isolation circuit.
Further, the described first resistance resistor network that is single resistor or is made up of in mode that is in parallel or series connection multiple resistor; The resistor network that described second resistance is single resistor or is made up of in mode that is in parallel or series connection multiple resistor.。
Compared to prior art, the beneficial effect of a kind of LED drive circuit that the utility model embodiment provides is: connect the output of described source voltage control circuit and the first voltage signal inputs of described error amplifying circuit by closed loop connecting circuit, when power initiation, form a temporary transient closed loop, make electric power output voltage Vout to stablize rising, prevent from exporting overshoot.When electric power output voltage Vout is in stable state, the first resistance R1 in closed loop connecting circuit and the second resistance R2 dividing potential drop, make the first electric capacity C1 can bear higher voltage, such as can use the patch capacitor that withstand voltage is lower, cost is lower, and taking PCB surface amasss little, and layout has superiority.Under stable situation, RB346, RB365 are as the dummy load use exported simultaneously, and do not need to add dummy load again, devices use rate obtains optimization.LED constant current can be realized control and prevent from producing voltage overshoot phenomenon during power initiation, protection LED, ensure that hardware cost is low simultaneously.
Accompanying drawing explanation
Fig. 1 is the structured flowchart of a kind of LED drive circuit of the utility model embodiment;
Fig. 2 is the circuit diagram of the closed loop connecting circuit 5 in Fig. 1;
Fig. 3 is the structured flowchart of a kind of LED drive circuit of another embodiment of the utility model;
Fig. 4 is the circuit diagram of a kind of LED drive circuit of Fig. 3.
Embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, the technical scheme in the utility model embodiment is clearly and completely described.
Refer to Fig. 1, it is the theory diagram of a kind of LED drive circuit that the utility model embodiment provides, and comprises LED group circuit 1, error amplifying circuit 2, source voltage control circuit 3, reference voltage source 4 and closed loop connecting circuit 5;
The output of described source voltage control circuit 3 connects the power end of described LED group circuit 1;
First voltage signal inputs of described error amplifying circuit 2 is connected with the signals collecting end of described LED group circuit 1; Second voltage signal inputs of described error amplifying circuit 2 is connected with described reference voltage source 4; The signal output part of described error amplifying circuit 2 is connected with the input of described source voltage control circuit 3;
Described closed loop connecting circuit 5 connects the output of described source voltage control circuit 3 and the first voltage signal inputs of described error amplifying circuit 2.
Particularly, described closed loop connecting circuit 5 comprises the first resistance R1, the second resistance R2 and the first electric capacity C1.
As shown in Figure 2, it is the circuit diagram of the connecting circuit of closed loop described in Fig. 15.
The first end of described first resistance R1 connects the output of described source voltage control circuit 3;
The first end of described second resistance R2 connects second end of described first resistance R1, and the second end ground connection of described second resistance R2;
The first end of described first electric capacity C1 connects second end of described first resistance R1, and second end of described first electric capacity C1 connects the first voltage signal inputs of described error amplifying circuit 2.
Wherein, the described first resistance R1 resistor network that is single resistor or is made up of in mode that is in parallel or series connection multiple resistor; The resistor network that described second resistance R2 is single resistor or is made up of in mode that is in parallel or series connection multiple resistor.The effect that described first electric capacity C1 plays when electric power output voltage Vout stablizes " every straight ".
The operation principle of a kind of LED drive current that the present embodiment provides is as follows: rise from 0 at electric power output voltage Vout, and in the process of the non-conducting of LED group, electric power output voltage Vout is input to the first voltage signal inputs of described error amplifying circuit 2 by the first resistance R1 in described closed loop connecting circuit 5, the first electric capacity C1; Electric power output voltage Vout is exported a control signal in order to control described electric power output voltage Vout with reference voltage by described error amplifying circuit 2 more afterwards, thus can not occur the phenomenon of overshoot at Vout ascent stage.When electric power output voltage Vout is in stable state, the conducting of LED group, described error amplifying circuit gathers the voltage signal of LED group, and compares with reference voltage, export a control signal more afterwards in order to control described electric power output voltage Vout, thus can the constant current of control LED group.
Compared with the prior art, closed loop connecting circuit in the utility model embodiment connects the output of described source voltage control circuit and the first voltage signal inputs of described error amplifying circuit, when power initiation, form a temporary transient closed loop, make electric power output voltage Vout to stablize rising, prevent from exporting overshoot; When electric power output voltage Vout is in stable state, the first resistance R1 and the second resistance R2 dividing potential drop, make the first electric capacity C1 can bear higher voltage, such as can use the patch capacitor that 50V is withstand voltage, cost is lower, and takies PCB surface and amass little, and layout has superiority.Under stable situation, RB346, RB365 are as the dummy load use exported simultaneously, and do not need to add dummy load again, devices use rate obtains optimization.
As shown in Figure 3, it is the structured flowchart of the LED drive circuit of another embodiment of the utility model.The LED drive circuit that the another kind of embodiment of the utility model provides comprises LED group circuit 1, error amplifying circuit 2, source voltage control circuit 3, reference voltage source 4 and closed loop connecting circuit 5 in an embodiment, in addition, bleeder circuit 6 and RC filter circuit 7 is also comprised.Described reference voltage source 4 is connected to the second voltage signal inputs of described error amplifying circuit 2 by described bleeder circuit 6.The signals collecting end of described LED group circuit 1 is connected with the first voltage signal inputs of described error amplifying circuit 2 by described RC filter circuit 7.
Refer to Fig. 4, it is the circuit diagram of a kind of LED drive circuit in Fig. 3.Wherein, Vout is the output voltage of described source voltage control circuit 3 (not showing in Fig. 4), and V0 is reference voltage, and V1 is the output voltage of described error amplifying circuit 2.
Described LED group circuit 1 comprises N number of LED and sampling resistor Rs of connecting successively, N >=1; Wherein, the power end of the just very described LED group circuit 1 of first LED; The negative pole of N number of LED is connected with the first end of described sampling resistor Rs, the second end ground connection of described sampling resistor Rs; The first end of described sampling resistor Rs is the signals collecting end of described LED group circuit 1.In the present embodiment, N=3, described LED group circuit 1 comprises D1, D2, D3 in Fig. 4 and sampling resistor Rs.The effect of described sampling resistor Rs changes the current signal of the described LED group circuit 1 of circulation into voltage signal, so that described error amplifying circuit 2 processes.
Described error amplifying circuit 2 comprises operational amplifier A 1, the 3rd resistance R3, the second electric capacity C2 and the 3rd electric capacity C3.The normal phase input end of described operational amplifier A 1 is the second voltage signal inputs of described error amplifying circuit 2, the inverting input of described operational amplifier A 1 is the first voltage signal inputs of described error amplifying circuit 2, and the output of described operational amplifier A 1 is the signal output part of described error amplifying circuit 2; The first end of described 3rd resistance R3 connects the output of described operational amplifier A 1, and second end of described 3rd resistance R3 connects the first end of described second electric capacity C2; Second end of described second electric capacity C2 connects the inverting input of described operational amplifier A 1; The first end of described 3rd electric capacity C3 connects the output of described operational amplifier A 1, and second end of described 3rd electric capacity C3 connects the inverting input of described operational amplifier A 1.Described operational amplifier A 1, the 3rd resistance R3, the second electric capacity C2 and the 3rd electric capacity C3 form negative feedback amplifier circuit.
Described bleeder circuit 6 comprises the 4th resistance R4, the 5th resistance R5 and the 4th electric capacity C4; The first end of described 4th resistance R4 connects described reference voltage source 4, and second end of described 4th resistance R4 connects the first end of described 5th resistance R5; The first end of described 5th resistance R5 connects the second voltage signal inputs of described error amplifying circuit 2, the second end ground connection of described 5th resistance R5; Described 4th electric capacity C4 is in parallel with described 5th resistance R5.Described reference voltage source 4, after described bleeder circuit 6 dividing potential drop, can provide the reference voltage of lower (lower than 1V) for described error amplifying circuit 2; Different reference voltages can be exported from the ratio of described 5th resistance R5 by adjusting described 4th resistance R4.Described 4th electric capacity C4 is used for the high fdrequency component in filtering criterion voltage source 4.
Described RC filter circuit 7 comprises the 6th resistance R6 and the 5th electric capacity C5; The first end of described 6th resistance R6 connects the signals collecting end of described LED group circuit 1, and second end of described 6th resistance R6 connects the first end of described 5th electric capacity C5; The second end ground connection of described 5th electric capacity C5; Second end of described 6th resistance R6 connects the first voltage signal inputs of described error amplifying circuit 2.Described 6th resistance R6 plays the effect of current limliting in circuit, and described 5th electric capacity C5 plays the effect of smothing filtering; Amplitude-frequency characteristic and the phase-frequency characteristic of circuit can be improved by adjusting described 6th resistance R6 and described 5th electric capacity C5.
As further improvement of this embodiment, described LED drive circuit can also comprise optical coupling isolation circuit; The signal output part of described error amplifying circuit 2 is connected with the input of described source voltage control circuit 3 by described optical coupling isolation circuit.Can be isolated with described error amplifying circuit 2 by described source voltage control circuit 3 by described optical coupling isolation circuit, avoid the forceful electric power in described error amplifying circuit 2 to disturb weak electric signal in described source voltage control circuit 3.
Should be noted that, another embodiment of the present utility model is a better embodiment, but described bleeder circuit 6, RC filter circuit 7 and optical coupling isolation circuit are not necessary, the LED drive circuit namely gone up in an embodiment also can realize basic object of the present utility model.
The beneficial effect of a kind of LED drive circuit that the utility model embodiment provides is: connect the output of described source voltage control circuit and the first voltage signal inputs of described error amplifying circuit by closed loop connecting circuit, when power initiation, form a temporary transient closed loop, make electric power output voltage Vout to stablize rising, prevent from exporting overshoot.When electric power output voltage Vout is in stable state, the first resistance R1 and the second resistance R2 dividing potential drop, make the first electric capacity C1 can bear higher voltage, such as can use the patch capacitor that withstand voltage is lower, cost is lower, and takies PCB surface and amass little, and layout has superiority.Under stable situation, RB346, RB365 are as the dummy load use exported simultaneously, and do not need to add dummy load again, devices use rate obtains optimization.Can realize LED constant current control and prevent from producing voltage overshoot phenomenon during power initiation, protection LED, the cost compare of hardware is low simultaneously.
Below be only preferred implementation of the present utility model, it should be pointed out that above-mentioned preferred implementation should not be considered as restriction of the present utility model.Protection range of the present utility model should be as the criterion with claim limited range.For those skilled in the art, not departing from spirit and scope of the present utility model, can also make some improvements and modifications, these improvements and modifications also should be considered as protection range of the present utility model.
Claims (10)
1. a LED drive circuit, is characterized in that: comprise LED group circuit, error amplifying circuit, source voltage control circuit, reference voltage source and closed loop connecting circuit;
The output of described source voltage control circuit connects the power end of described LED group circuit;
First voltage signal inputs of described error amplifying circuit is connected with the signals collecting end of described LED group circuit; Second voltage signal inputs of described error amplifying circuit is connected with described reference voltage source; The signal output part of described error amplifying circuit is connected with the input of described source voltage control circuit;
Described closed loop connecting circuit connects the output of described source voltage control circuit and the first voltage signal inputs of described error amplifying circuit.
2. a kind of LED drive circuit as claimed in claim 1, is characterized in that:
Described closed loop connecting circuit comprises the first resistance, the second resistance and the first electric capacity;
The first end of described first resistance connects the output of described source voltage control circuit;
The first end of described second resistance connects the second end of described first resistance, and the second end ground connection of described second resistance;
The first end of described first electric capacity connects the second end of described first resistance, and the second end of described first electric capacity connects the first voltage signal inputs of described error amplifying circuit.
3. a kind of LED drive circuit as claimed in claim 1, is characterized in that: described LED group circuit comprises N number of LED and sampling resistor of connecting successively, N >=1; Wherein, the power end of the just very described LED group circuit of first LED; The negative pole of N number of LED is connected with the first end of described sampling resistor, the second end ground connection of described sampling resistor; The first end of described sampling resistor is the signals collecting end of described LED group circuit.
4. a kind of LED drive circuit as claimed in claim 1, is characterized in that: described error amplifying circuit comprises operational amplifier, the 3rd resistance, the second electric capacity and the 3rd electric capacity; The normal phase input end of described operational amplifier is the second voltage signal inputs of described error amplifying circuit, the inverting input of described operational amplifier is the first voltage signal inputs of described error amplifying circuit, and the output of described operational amplifier is the signal output part of described error amplifying circuit; The first end of described 3rd resistance connects the output of described operational amplifier, and the second end of described 3rd resistance connects the first end of described second electric capacity; Second end of described second electric capacity connects the inverting input of described operational amplifier; The first end of described 3rd electric capacity connects the output of described operational amplifier, and the second end of described 3rd electric capacity connects the inverting input of described operational amplifier.
5. a kind of LED drive circuit as claimed in claim 1, is characterized in that: described LED drive circuit also comprises bleeder circuit; Described reference voltage source is connected to the second voltage signal inputs of described error amplifying circuit by described bleeder circuit.
6. a kind of LED drive circuit as claimed in claim 5, is characterized in that: described bleeder circuit comprises the 4th resistance, the 5th resistance and the 4th electric capacity; The first end of described 4th resistance connects described reference voltage source, and the second end of described 4th resistance connects the first end of described 5th resistance; The first end of described 5th resistance connects the second voltage signal inputs of described error amplifying circuit, the second end ground connection of described 5th resistance; Described 4th electric capacity and described 5th resistor coupled in parallel.
7. a kind of LED drive circuit as claimed in claim 1, is characterized in that: described LED drive circuit also comprises RC filter circuit; The signals collecting end of described LED group circuit is connected with the first voltage signal inputs of described error amplifying circuit by described RC filter circuit.
8. a kind of LED drive circuit as claimed in claim 7, is characterized in that: described RC filter circuit comprises the 6th resistance and the 5th electric capacity; The first end of described 6th resistance connects the signals collecting end of described LED group circuit, and the second end of described 6th resistance connects the first end of described 5th electric capacity; Second end ground connection of described 5th electric capacity; Second end of described 6th resistance connects the first voltage signal inputs of described error amplifying circuit.
9. a kind of LED drive circuit as claimed in claim 1, is characterized in that: described LED drive circuit also comprises optical coupling isolation circuit; The signal output part of described error amplifying circuit is connected with the input of described source voltage control circuit by described optical coupling isolation circuit.
10. a kind of LED drive circuit as claimed in claim 1, is characterized in that: the resistor network that described first resistance is single resistor or is made up of in mode that is in parallel or series connection multiple resistor; The resistor network that described second resistance is single resistor or is made up of in mode that is in parallel or series connection multiple resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420865364.1U CN204362375U (en) | 2014-12-30 | 2014-12-30 | A kind of LED drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420865364.1U CN204362375U (en) | 2014-12-30 | 2014-12-30 | A kind of LED drive circuit |
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| Publication Number | Publication Date |
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| CN204362375U true CN204362375U (en) | 2015-05-27 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201420865364.1U Active CN204362375U (en) | 2014-12-30 | 2014-12-30 | A kind of LED drive circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114423115A (en) * | 2022-02-08 | 2022-04-29 | 广东天波信息技术股份有限公司 | Low-cost LED drive circuit and low-voltage power consumption equipment |
-
2014
- 2014-12-30 CN CN201420865364.1U patent/CN204362375U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114423115A (en) * | 2022-02-08 | 2022-04-29 | 广东天波信息技术股份有限公司 | Low-cost LED drive circuit and low-voltage power consumption equipment |
| CN114423115B (en) * | 2022-02-08 | 2023-10-31 | 广东天波信息技术股份有限公司 | Low-cost LED drive circuit and low-voltage electric equipment |
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