CN204031542U - Led drive circuit - Google Patents
Led drive circuit Download PDFInfo
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- CN204031542U CN204031542U CN201420422601.7U CN201420422601U CN204031542U CN 204031542 U CN204031542 U CN 204031542U CN 201420422601 U CN201420422601 U CN 201420422601U CN 204031542 U CN204031542 U CN 204031542U
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Abstract
The utility model discloses a kind of LED drive circuit, comprise AC power input rectifying and electromagnetic interference filter circuit, control circuit and buck configuration switching circuit, wherein: described AC power input rectifying is connected with AC power with the input of electromagnetic interference filter circuit, output is connected with the first terminal of described buck configuration switching circuit; The first terminal of described buck configuration switching circuit is connected with the output of electromagnetic interference filter circuit with described AC power input rectifying, second terminal is connected with the first terminal of described control circuit, and load circuit is across between the third and fourth terminal of described buck configuration switching circuit; The first terminal of described control circuit is connected with the second terminal of described buck configuration switching circuit, and the second terminal is connected with reference to ground.Have according to the LED drive circuit of the utility model embodiment that high conversion efficiency, systematic part quantity are few, the advantage of small size.
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: described AC power input rectifying is connected with AC power with the input of electromagnetic interference filter circuit, output is connected with the first terminal of described buck configuration switching circuit; The first terminal of described buck configuration switching circuit is connected with the output of electromagnetic interference filter circuit with described AC power input rectifying, second terminal is connected with the first terminal of described control circuit, and load circuit is across between the third and fourth terminal of described buck configuration switching circuit; The first terminal of described control circuit is connected with the second terminal of described buck configuration switching circuit, and the second terminal is connected with reference to ground.
Have according to the LED drive circuit of the utility model embodiment that high conversion efficiency, systematic part quantity are few, the advantage of small size.
Accompanying drawing explanation
The utility model can be understood better in the description of embodiment of the present utility model 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
The characteristic sum exemplary embodiment of the utility model various aspects will be described in detail below.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: AC power (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 buck configuration switching circuit 3; The first terminal of buck configuration switching circuit 3 is connected with the output of AC input rectifying with EMI filter circuit 1, second terminal is connected with the first 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 second terminal of buck configuration switching circuit 3, and the second terminal is connected with reference to ground.
Above-mentioned LED drive circuit have fixed current export, without the need to current sense resistor, feature without the need to starting resistance and valley conduction, the problems such as the part that can overcome LED of the prior art is many, volume is large, power supply conversion efficiency is low, caloric value is large.
As shown in Figure 1, AC input rectifying and EMI filter circuit 1 comprise: fuse F1, rectifier diode D1, D2, D3, D4, filter inductance L1, and filter capacitor C1, 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.
Control circuit 2 comprises: control chip U1 and Power supply electric capacity C3, wherein, the first terminal of power supply pin VDD and the C3 of control chip U1 is connected, second terminal of grounding leg GND and the C3 of U1 is all connected to reference to ground, and the drain electrode pin (Drain) of chip U1 is connected to the second terminal of buck configuration switching circuit 3 as the first terminal of control circuit.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.
Buck configuration switching circuit 3 comprises: filter capacitor C4, step-down switching inductance L 2, sustained diode 5 and output dummy load R1, wherein, filter capacitor C4 and export dummy load R1 and be connected in parallel, and two of filter capacitor C4 terminals are connected with load circuit respectively as the third and fourth terminal of buck configuration switching circuit 3; The first terminal of sustained diode 5, the first terminal of the first terminal and filter capacitor C4 exporting dummy load R1 are connected with the first terminal of buck configuration switching circuit 3 respectively; The first terminal of step-down switching inductance L 2 is connected with the second terminal of the second terminal and filter capacitor C4 that export dummy load R1, and the second terminal is connected with the second terminal of sustained diode 5; Second terminal of sustained diode 5 is connected with the first terminal of control circuit 2 as the second terminal of buck configuration switching circuit 3.
Specifically, in the embodiment shown in fig. 1, control chip U1 comprises three function pin:
Power supply pin (VDD), is connected to GND pin by Power supply electric capacity C3, for powering for control chip U1.When the metal oxide semiconductor field effect tube (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.
Drain electrode pin (Drain); this drain electrode pin is the drain electrode pin 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 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.
Grounding leg (GND), with reference to be connected, for the benchmark as control chip U1.
In FIG, the drain electrode pin of control chip U1 is connected with the second terminal of buck configuration switching circuit 3 as the first terminal of control circuit 2; The first terminal of Power supply electric capacity C3 is connected with the power supply pin of control chip U1; Second terminal of Power supply electric capacity C3 as control circuit 2 the second terminal with reference to be connected.When the MOSFET of control chip U1 inside is turned off, the level at drain electrode pin place is high level, is now that Power supply electric capacity C3 charges by the drain electrode of MOSFET.
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 the setting threshold 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 the setting threshold 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 by the energy stored during conducting 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 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 the setting threshold of control chip U1 inside, control chip U1 also can quit work at once, until temperature drops to another setting threshold 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 fixed current export, but this LED drive circuit is without the need to the parts such as current sense resistor, starting resistance, and have employed the structure of valley conduction, thus have that high conversion efficiency, systematic part quantity are few, the advantage of small size.
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 signal arrows in accompanying drawing should be considered to be only exemplary, instead of restrictive, indicates unless otherwise specifically.When term be also contemplated as the ability of separation or combination is not known time, the combination of assembly or step also will be considered to describe.
Claims (7)
1. a LED drive circuit, comprises AC power input rectifying and electromagnetic interference filter circuit, control circuit and buck configuration switching circuit, wherein:
Described AC power 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 buck configuration switching circuit;
The first terminal of described buck configuration switching circuit is connected with the output of electromagnetic interference filter circuit with described AC power input rectifying, second terminal is connected with the first terminal of described control circuit, and load circuit is across between the third and fourth terminal of described buck configuration switching circuit;
The first terminal of described control circuit is connected with the second terminal of described buck configuration switching circuit, and the second terminal is connected with reference to ground.
2. LED drive circuit according to claim 1, is characterized in that, described control circuit comprises control chip, and described control chip only comprises following functions pin:
Drain electrode pin, described drain electrode pin is the drain electrode pin of the metal oxide semiconductor field effect tube MOSFET of described control chip inside, for controlling shutoff and the conducting of described MOSFET;
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;
Second terminal of described Power supply electric capacity as described control circuit the second terminal with reference to be connected;
The drain electrode pin of described control chip is connected with the second terminal of described buck configuration switching circuit as the first terminal of described control circuit;
The grounding leg of described control chip is connected with reference to ground.
4. LED drive circuit according to claim 1, is characterized in that, described buck configuration switching circuit comprises: filter capacitor, step-down switching inductance, fly-wheel diode and output dummy load, wherein:
Described filter capacitor and described output dummy load are connected in parallel, and two of described filter capacitor terminals are connected with described load circuit respectively as the third and fourth terminal of described buck configuration switching circuit;
The first terminal of the first terminal of described fly-wheel diode, the first terminal of described output dummy load and described filter capacitor is connected with the first terminal of described buck configuration switching circuit respectively;
The first terminal of described step-down switching inductance is connected with the second terminal of described filter capacitor with the second terminal of described output dummy load, and the second terminal is connected with the second terminal of described fly-wheel diode;
Second terminal of described fly-wheel diode is connected with the first terminal of described control circuit as the second terminal of described buck configuration switching circuit.
5. 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.
6. 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.
7. LED drive circuit according to claim 6, it is characterized in that, described AC power 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 |
|---|---|---|---|
| CN201420422601.7U CN204031542U (en) | 2014-07-29 | 2014-07-29 | Led drive circuit |
| TW103217776U TWM498943U (en) | 2014-07-29 | 2014-10-06 | Led drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420422601.7U CN204031542U (en) | 2014-07-29 | 2014-07-29 | Led drive circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204031542U true CN204031542U (en) | 2014-12-17 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420422601.7U Active CN204031542U (en) | 2014-07-29 | 2014-07-29 | Led drive circuit |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN204031542U (en) |
| TW (1) | TWM498943U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI562676B (en) * | 2015-02-17 | 2016-12-11 |
-
2014
- 2014-07-29 CN CN201420422601.7U patent/CN204031542U/en active Active
- 2014-10-06 TW TW103217776U patent/TWM498943U/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 |
|---|---|
| TWM498943U (en) | 2015-04-11 |
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