CN204031548U - Led drive circuit - Google Patents
Led drive circuit Download PDFInfo
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- CN204031548U CN204031548U CN201420455963.6U CN201420455963U CN204031548U CN 204031548 U CN204031548 U CN 204031548U CN 201420455963 U CN201420455963 U CN 201420455963U CN 204031548 U CN204031548 U CN 204031548U
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Abstract
The utility model discloses a kind of LED drive circuit, comprise and exchange input rectifying and electromagnetic interference filter circuit, control circuit and buck configuration switching circuit, wherein: exchange input rectifying and be connected with AC power with the input of electromagnetic interference filter circuit, and exchange input rectifying and be connected with the first terminal of control circuit with the output of electromagnetic interference filter circuit; The first terminal of buck configuration switching circuit is also connected with the first terminal of control circuit, second terminal of buck configuration switching circuit is connected with the second terminal of control circuit, and load circuit is across between the 3rd terminal and the 4th terminal of buck configuration switching circuit of buck configuration switching circuit; And the first terminal of control circuit with exchange input rectifying and be connected with the first terminal of buck configuration switching circuit with the output of electromagnetic interference filter circuit, second terminal of control circuit is connected with the second terminal of buck configuration switching circuit, and the 3rd terminal of control circuit is connected with reference to ground.
Description
Technical field
The utility model relates to circuit field, relates more specifically to a kind of LED drive circuit.
Background technology
At present, light-emitting diode (LED) technology reaches its maturity, and market has been seen everywhere various LED lamp.This trend meets requirement that is energy-conservation, low-carbon (LC).But, along with LED lamp comes into huge numbers of families, also more and more higher to the requirement of luminaire efficiency and cost.But LED power is in the market all generally low-voltage, high-current type, and such LED power exists the shortcomings such as part is many, volume is large, power supply conversion efficiency is low, caloric value is large.Therefore, need a kind of novel LED drive circuit to solve the problem.
Utility model content
One or more problems in view of the above, the utility model provides a kind of novel LED drive circuit.
According to the LED drive circuit of the utility model embodiment, comprise AC power input rectifying and electromagnetic interference filter circuit, control circuit and buck configuration switching circuit, wherein: exchange input rectifying and be connected with AC power with the input of electromagnetic interference filter circuit, output is connected with the first terminal of control circuit; The first terminal of control circuit with exchange input rectifying and be connected with the first terminal of buck configuration switching circuit with the output of electromagnetic interference filter circuit, second terminal is connected with the second terminal of buck configuration switching circuit, and the third and fourth terminal is connected with reference to ground; And the first terminal of buck configuration switching circuit is connected with the first terminal of control circuit, the second terminal is connected with the second terminal of control circuit, and load circuit is across between the 3rd terminal and the 4th terminal of buck configuration switching circuit.
According to the LED drive circuit of the utility model embodiment, there is high conversion efficiency, systematic part quantity is few, volume is little advantage.
Accompanying drawing explanation
The utility model can be understood better to the description of embodiment of the present utility model from below in conjunction with accompanying drawing, wherein:
Fig. 1 shows the circuit diagram of the LED drive circuit according to the utility model embodiment.
Embodiment
Describe the characteristic sum exemplary embodiment of the utility model various aspects below with reference to accompanying drawings in detail.Description below covers many details, to provide complete understanding of the present utility model.But, it will be apparent to one skilled in the art that the utility model can be implemented when not needing some details in these details.Below the description of embodiment is only used to by illustrating example of the present utility model to provide to the clearer understanding of the utility model.Any concrete configuration that the utility model proposes below being never limited to, but under the prerequisite not departing from spirit of the present utility model, cover any amendment of coherent element or parts, replacement and improvement.
LED drive circuit according to the utility model embodiment is developed based on buck configuration switching circuit.Below in conjunction with Fig. 1, describe the LED drive circuit according to the utility model embodiment in detail.
Fig. 1 shows the circuit diagram of the LED drive circuit according to the utility model embodiment.As shown in Figure 1, this LED drive circuit comprises: exchange (AC) input rectifying and electromagnetic interference (EMI) filter circuit 1, control circuit 2 and buck configuration switching circuit 3.
Wherein, AC input rectifying is connected with AC power with the input of EMI filter circuit 1, and output is connected with the first terminal of control circuit 2; The first terminal of buck configuration switching circuit 3 is connected with the first terminal of control circuit 2 equally, second terminal of buck configuration switching circuit 3 is connected with the second terminal of control circuit 2, and the load circuit that LED drive circuit drives is across between the third and fourth terminal of buck configuration switching circuit 3; The first terminal of control circuit 2 is connected with the first terminal of buck configuration switching circuit 3 with the output of EMI filter circuit 1 with AC input rectifying simultaneously, second terminal of control circuit 2 is connected with the second terminal of buck configuration switching circuit 3, and the 3rd terminal of control circuit 2 is connected with reference to ground.
Above-mentioned LED drive circuit has electric current stable output (such as, 40mA ~ 80mA), without the need to current sense resistor, feature without the need to starting resistance, built-in fly-wheel diode and valley conduction, the problem such as the part that can overcome LED drive circuit of the prior art is many, volume is large, power supply conversion efficiency is low, caloric value is large.
As shown in Figure 1, in one embodiment, AC input rectifying and EMI filter circuit 1 comprise: fuse F1, rectifier diode D1, D2, D3, D4, filter inductance L1, and filter capacitor C1 and C2.Wherein, four rectifier diodes D1, D2, D3, D4 are connected with the structure of bridge rectifier, carry out rectification for the interchange AC signal of input.In addition, filter inductance L1 and filter capacitor C1, C2 together form EMI filter circuit wherein, for carrying out filtering to the signal after rectification.
In one embodiment, control circuit 2 comprises: control chip U1 and Power supply electric capacity C3.Wherein, control chip U1 comprises drain electrode pin (Drain), high presser feet (HV), grounding leg (GND) and power supply pin (VDD) four function pin, specific as follows:
(1) Drain; this drain electrode pin is the drain electrode of the metal oxide semiconductor field effect tube (MOSFET) of control chip U1 inside; for shutoff and the conducting of control MOSFET, control circuit 2 also carries out overvoltage protection (OVP) monitoring by the demagnetization time of the drain waveforms at the pin place that drains simultaneously.When the demagnetization time is less than predetermined threshold, control circuit 2 will perform the relevant operation of overvoltage protection.
(2) HV, this high presser feet is the negative electrode of the fly-wheel diode of control chip U1 inside.When the MOSFET of U1 inside turns off, electric energy is discharged to load circuit by this built-in fly-wheel diode by the step-down switching inductance L 2 in buck configuration switching circuit 3.
(3) GND, with reference to be connected, for the benchmark as control chip U1.
(4) VDD, is connected to GND by Power supply electric capacity C3, for powering for control chip U1.When the MOSFET of control chip U1 inside is turned off, its drain electrode is high level, and now the drain electrode of the MOSFET by control chip U1 inside is charged by Power supply electric capacity C3.
Wherein, the first terminal of VDD and C3 is connected, and second terminal of GND and C3 is all connected to reference to ground.HV is connected with the first terminal of buck configuration switching circuit 3 with the output of EMI filter circuit 1 with AC input rectifying as the first terminal of control circuit 2 simultaneously, Drain is connected with the second terminal of buck configuration switching circuit 3 as the second terminal of control circuit 2, and, 3rd terminal of the second Terminal control circuit 2 of C3, GND is the 4th terminal of control circuit 2.According to embodiment of the present utility model, this control circuit 2 is responsible for the work controlling whole LED drive circuit, the demagnetization process, overvoltage protection etc. of such as controlled hypotension configuration switches circuit 3.In some embodiment of the present utility model, this control chip can be pulse-width modulation (PWM) chip.
In one embodiment, buck configuration switching circuit 3 comprises: filter capacitor C4, step-down switching inductance L 2 and output dummy load R1.Wherein, filter capacitor C4 is with output dummy load R1 and be connected in parallel, the first terminal of this parallel-connection structure is the 3rd terminal of buck configuration switching circuit 3 and the second terminal of this parallel-connection structure is the 4th terminal of buck configuration switching circuit 3, and as mentioned above, cross-over connection therebetween has load circuit; Step-down switching inductance L 2 is serially connected between the second terminal of control circuit 2 and the 4th terminal of buck configuration switching circuit 3.
Particularly, in the LED drive circuit shown in Fig. 1, when AC input rectifying is connected with AC power supplies with the input of EMI filter circuit 1, the Power supply electric capacity C3 that the drain electrode pin of the control chip U1 in control circuit 2 connects to the power supply pin of control chip U1 charges.When the voltage at the power supply pin place of control chip U1 reaches setting threshold (T1) of control chip U1 inside, control chip U1 starts working.When the MOSFET conducting of control chip U1 inside, LED drive circuit starts to power to load circuit, and the inductance L 2 simultaneously in buck configuration switching circuit 3 starts energy storage; When the current peak of the inductance L 2 in buck configuration switching circuit 3 reaches setting threshold (T2) of control chip U1 inside, the MOSFET of control chip U1 inside turns off, and inductance L 2 starts to demagnetize to be powered to the power supply pin of control chip U1 to load circuit release via the high presser feet of control chip U1 by the fly-wheel diode of the energy stored during conducting by control chip U1 inside simultaneously.When the fault offset of the inductance L 2 in buck configuration switching circuit 3 is complete, the voltage at the drain electrode pin place of control chip U1 starts to decline, and control chip U1 opens the MOSFET of control chip U1 inside again to realize valley conduction after this situation being detected.In the MOSFET blocking interval of control chip U1 inside, control chip U1 is by the demagnetization time of detecting inductance L 2, if the demagnetization time is less than the internal threshold (T3) of control chip U1, then control chip U1 thinks to there occurs output overvoltage state, and control chip U1 quits work at once and again starts working after the time through control chip U1 inner setting.When the temperature that control chip U1 occurs exceedes setting threshold (T4) of control chip U1 inside, control chip U1 also can quit work at once, until temperature drops to another setting threshold (T5) of control chip U1 inside, control chip U1 just resumes work.
As can be seen from Figure 1, the LED drive circuit provided according to the utility model embodiment is based on the exploitation of common buck configuration switching circuit, there is stabling current export (such as, 40mA ~ 80mA), and this LED drive circuit is without the need to the parts such as current sense resistor, starting resistance, and have employed the structure of built-in fly-wheel diode and valley conduction, thus there is high conversion efficiency, systematic part quantity is few, volume is little advantage.
Below the utility model is described with reference to specific embodiment of the utility model, but those skilled in the art all understand, various amendment, combination and change can be carried out to these specific embodiments, and the spirit and scope of the present utility model by claims or its equivalents can not be departed from.In addition, any sense in accompanying drawing should be considered to be only exemplary, instead of restrictive, indicates unless otherwise specifically.
Claims (8)
1. a LED drive circuit, comprises and exchanges input rectifying and electromagnetic interference filter circuit, control circuit and buck configuration switching circuit, wherein:
Described interchange input rectifying is connected with AC power with the input of electromagnetic interference filter circuit, and output is connected with the first terminal of described control circuit;
The first terminal of described control circuit is connected with the first terminal of described buck configuration switching circuit with the output of electromagnetic interference filter circuit with the described input rectifying that exchanges, second terminal is connected with the second terminal of described buck configuration switching circuit, and the third and fourth terminal is connected with reference to ground; And
The first terminal of described buck configuration switching circuit is connected with the first terminal of described control circuit, second terminal is connected with the second terminal of described control circuit, and load circuit is across between the 3rd terminal and the 4th terminal of described buck configuration switching circuit.
2. LED drive circuit according to claim 1, is characterized in that, described control circuit comprises control chip, and wherein said control chip only comprises following functions pin:
Drain electrode pin, described drain electrode pin is the drain electrode of the metal oxide semiconductor field effect tube MOSFET of described control chip inside, for controlling shutoff and the conducting of described MOSFET;
High presser feet, described high presser feet is the negative electrode of the fly-wheel diode of described control chip inside;
Power supply pin, for powering for described control chip;
Grounding leg, as the benchmark of described control chip.
3. LED drive circuit according to claim 2, is characterized in that, described control circuit also comprises Power supply electric capacity, wherein:
The first terminal of described Power supply electric capacity is connected with the power supply pin of described control chip, and the second terminal is the 3rd terminal of described control circuit;
The drain electrode pin of described control chip is the second terminal of described control circuit;
The grounding leg of described control chip is the 4th terminal of described control circuit.
4. LED drive circuit according to claim 2, is characterized in that, described buck configuration switching circuit comprises: filter capacitor, step-down switching inductance and output dummy load, wherein:
Described filter capacitor and described output dummy load are connected in parallel, and the first terminal of the parallel-connection structure of described filter capacitor and described output dummy load is the 3rd terminal of described buck configuration switching circuit and the second terminal of the parallel-connection structure of described filter capacitor and described output dummy load is the 4th terminal of described buck configuration switching circuit; And
Described step-down switching inductance is serially connected between the second terminal of described control circuit and the 4th terminal of described buck configuration switching circuit.
5. LED drive circuit according to claim 4, is characterized in that, electric energy is discharged to described load circuit by the fly-wheel diode of described control chip inside by described step-down switching inductance.
6. the LED drive circuit according to Claims 2 or 3, is characterized in that, described control circuit also carries out overvoltage protection monitoring by the demagnetization time of the drain waveforms at described drain electrode pin place.
7. LED drive circuit according to claim 3, is characterized in that, when the MOSFET of described control chip inside is turned off, the level at described drain electrode pin place is high level, is now described Power supply capacitor charging by the drain electrode of described MOSFET.
8. LED drive circuit according to claim 1, it is characterized in that, described interchange input rectifying and electromagnetic interference filter circuit comprise: rectifier bridge, filter inductance, the first filter capacitor and the second filter capacitor that fuse, four rectifier diodes are formed.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420455963.6U CN204031548U (en) | 2014-08-13 | 2014-08-13 | Led drive circuit |
| TW103219137U TWM499024U (en) | 2014-08-13 | 2014-10-29 | LED driver circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420455963.6U CN204031548U (en) | 2014-08-13 | 2014-08-13 | Led drive circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204031548U true CN204031548U (en) | 2014-12-17 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420455963.6U Active CN204031548U (en) | 2014-08-13 | 2014-08-13 | Led drive circuit |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN204031548U (en) |
| TW (1) | TWM499024U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI562676B (en) * | 2015-02-17 | 2016-12-11 |
-
2014
- 2014-08-13 CN CN201420455963.6U patent/CN204031548U/en active Active
- 2014-10-29 TW TW103219137U patent/TWM499024U/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI562676B (en) * | 2015-02-17 | 2016-12-11 |
Also Published As
| Publication number | Publication date |
|---|---|
| TWM499024U (en) | 2015-04-11 |
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