CN216437071U - Feedback circuit of switching power supply - Google Patents
Feedback circuit of switching power supply Download PDFInfo
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- CN216437071U CN216437071U CN202123152554.8U CN202123152554U CN216437071U CN 216437071 U CN216437071 U CN 216437071U CN 202123152554 U CN202123152554 U CN 202123152554U CN 216437071 U CN216437071 U CN 216437071U
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- power supply
- optical coupler
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Abstract
The utility model provides a switching power supply's feedback circuit, including optical coupler, three-terminal regulator, first resistance, first electric capacity, fourth resistance and sixth resistance. The first pin of the optical coupler is connected with the power output end, the second pin of the optical coupler is connected with the cathode of the three-terminal voltage-stabilizing source, the two ends of the first resistor are respectively connected with the first pin and the second pin of the optical coupler, and the two ends of the first capacitor are respectively connected with the first pin of the optical coupler and the cathode of the three-terminal voltage-stabilizing source for filtering. The anode of the three-terminal voltage regulator is grounded, and the feedback end of the three-terminal voltage regulator is connected with the output end of the power supply through a fourth resistor and is grounded through a sixth resistor. Through the first capacitor, noise waves of the input end of the optical coupler and the three-terminal voltage stabilizing source can be reduced, and burst interference signals generated when the load output by the power supply changes can be prevented from being transmitted to the power supply management chip through the optical coupler, so that misoperation of the power supply management chip is prevented, and the stability of the output power supply is ensured.
Description
[ technical field ] A method for producing a semiconductor device
The utility model belongs to the technical field of switching power supply's technique and specifically relates to a switching power supply's feedback circuit is related to.
[ background of the invention ]
As is known, a switching power supply is configured to perform rectification and filtering processing on an input power supply and then output the rectified power supply from a transformer, wherein the output voltage is fed back to a power management chip through a feedback circuit, and the power management chip controls the on/off or the magnitude of the output power supply of the transformer by controlling a power switch, so as to achieve a constant voltage effect. However, in the existing feedback circuit, when the load of the power output changes, interference is easily received, and further, an error feedback may occur, so that the power management chip works erroneously and the stability of the power output is affected.
Accordingly, the prior art is in need of improvement and development.
[ Utility model ] content
An object of the utility model is to provide a switching power supply's feedback circuit for feedback circuit receives the problem of interference easily among the solution current switching power supply.
The technical scheme of the utility model as follows: a feedback circuit of a switching power supply comprises an optical coupler, a three-terminal voltage regulator, a first resistor, a first capacitor, a fourth resistor and a sixth resistor;
the first pin of the optical coupler is connected with a power output end, the second pin of the optical coupler is connected with the cathode of the three-terminal voltage regulator, two ends of the first resistor are respectively connected with the first pin and the second pin of the optical coupler, and two ends of the first capacitor are respectively connected with the first pin of the optical coupler and the cathode of the three-terminal voltage regulator for filtering; the anode of the three-terminal voltage regulator is grounded, and the feedback end of the three-terminal voltage regulator is connected with the output end of the power supply through the fourth resistor and is grounded through the sixth resistor.
Further, the feedback circuit further comprises a second resistor, and the first pin of the optical coupler is connected to the power output terminal through the second resistor.
Furthermore, the feedback circuit further comprises a third resistor, a second capacitor and a third capacitor, wherein two ends of the second capacitor are respectively connected with a second pin of the optical coupler and a cathode of the three-terminal voltage regulator; the third resistor is connected with the third capacitor in series, and two ends of the third resistor after series connection are respectively connected with two ends of the second capacitor.
Further, the feedback circuit further comprises a fifth resistor, and the fifth resistor is connected in parallel with the sixth resistor.
Further, the three-terminal voltage regulator is an LM431 model chip.
The beneficial effects of the utility model reside in that: compared with the prior art, the utility model discloses a parallelly connected a first electric capacity behind the input of optical coupler and the reverse series connection of three-terminal regulator, can reduce the input of optical coupler and the clutter of three-terminal regulator, the sudden interference signal when can avoiding power output's load to change passes through the optical coupler and transmits for the power management chip to prevent power management chip malfunction, guarantee output power's stability.
[ description of the drawings ]
Fig. 1 is a schematic block diagram of a prior art switching power supply.
Fig. 2 is a schematic circuit diagram of the present invention.
[ detailed description ] embodiments
The present invention will be further described with reference to the accompanying drawings and embodiments.
Referring to fig. 1, the present invention provides a feedback circuit of a switching power supply.
The feedback circuit of the switching power supply comprises an optical coupler U1, a three-terminal voltage regulator U2, a first resistor R1, a first capacitor C1, a fourth resistor R4 and a sixth resistor R6. The first pin of the optical coupler U1 is connected with the power output end, the second pin is connected with the cathode of the three-terminal regulator U2, the two ends of the first resistor R1 are respectively connected with the first pin and the second pin of the optical coupler U1, and the two ends of the first capacitor C1 are respectively connected with the first pin of the optical coupler U1 and the cathode of the three-terminal regulator U2 for filtering. The anode of the three-terminal voltage regulator U2 is grounded, and the feedback end of the three-terminal voltage regulator U2 is connected with the power output end through a fourth resistor R4 and is grounded through a sixth resistor R6.
The utility model discloses an utilize three-terminal steady voltage source U2 cooperation sixth resistance R6 can provide the reference voltage of a definite value, and the pressure differential of cooperation optical coupler U1 first pin and second pin, realize that optical coupler U1 switches on and give the voltage feedback of power management chip when power output is too big, and then the power management chip utilizes power switch to reduce the power of transformer output, and there is not the feedback when the output power source is too little, and then the power management chip utilizes the power of power switch increase transformer output, with the feedback effect that realizes feedback circuit, in order to realize output power source's stability. Just the utility model discloses a parallelly connected first resistance R1 at optical coupler U1's input can raise the current threshold value, prevents optical coupler U1 misleading, and can improve optical coupler U1's interference immunity. In addition, the input end of the optical coupler U1 is reversely connected in series with the three-terminal voltage regulator U2 and then is connected in parallel with the first capacitor C1, noise waves of the input end of the optical coupler U1 and the three-terminal voltage regulator U2 can be reduced, burst interference signals when load output by a power supply changes can be prevented from being transmitted to the power supply management chip through the optical coupler U1, false operation of the power supply management chip is prevented, stability of the output power supply is guaranteed, and the phenomenon that the feedback circuit in the existing switching power supply is easily interfered by the burst interference signals caused by load change is solved.
In one embodiment, the feedback circuit further includes a second resistor R2, the first pin of the optocoupler U1 is connected to the power supply output terminal through the second resistor R2, and the second resistor R2 is used for current limiting.
In an embodiment, the feedback circuit further includes a third resistor R3, a second capacitor C2, and a third capacitor C3, and two ends of the second capacitor C2 are respectively connected to the second pin of the optocoupler U1 and the cathode of the three-terminal voltage regulator U2. The third resistor R3 is connected in series with the third capacitor C3, and both ends of the series connection are respectively connected to both ends of the second capacitor C2. The third resistor R3, the second capacitor C2, and the third capacitor C3 are used to provide the required feedback loop compensation for the optocoupler U1 to stabilize the control loop.
In an embodiment, the feedback circuit further includes a fifth resistor R5, the fifth resistor R5 is connected in parallel with the sixth resistor R6, and the third-end regulator U2 can output a desired reference voltage by using the fifth resistor R5 and the sixth resistor R6, wherein specifically, the third-end regulator U2 has a chip selected as an LM431 model.
The above embodiments of the present invention are only described, and it should be noted that, for those skilled in the art, modifications can be made without departing from the inventive concept, but these all fall into the protection scope of the present invention.
Claims (5)
1. A feedback circuit of a switching power supply is characterized by comprising an optical coupler, a three-terminal voltage regulator, a first resistor, a first capacitor, a fourth resistor and a sixth resistor;
the first pin of the optical coupler is connected with a power output end, the second pin of the optical coupler is connected with the cathode of the three-terminal voltage regulator, two ends of the first resistor are respectively connected with the first pin and the second pin of the optical coupler, and two ends of the first capacitor are respectively connected with the first pin of the optical coupler and the cathode of the three-terminal voltage regulator for filtering; the anode of the three-terminal voltage regulator is grounded, and the feedback end of the three-terminal voltage regulator is connected with the output end of the power supply through the fourth resistor and is grounded through the sixth resistor.
2. The feedback circuit of claim 1, further comprising a second resistor, wherein the first pin of the optocoupler is coupled to the power supply output via the second resistor.
3. The feedback circuit of the switching power supply according to claim 2, further comprising a third resistor, a second capacitor and a third capacitor, wherein two ends of the second capacitor are respectively connected to the second pin of the optocoupler and the cathode of the three-terminal regulator; the third resistor is connected with the third capacitor in series, and two ends of the third resistor after series connection are respectively connected with two ends of the second capacitor.
4. The feedback circuit of claim 3, further comprising a fifth resistor connected in parallel with the sixth resistor.
5. The feedback circuit of the switching power supply according to claim 4, wherein the three-terminal voltage regulator is an LM431 chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123152554.8U CN216437071U (en) | 2021-12-14 | 2021-12-14 | Feedback circuit of switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123152554.8U CN216437071U (en) | 2021-12-14 | 2021-12-14 | Feedback circuit of switching power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216437071U true CN216437071U (en) | 2022-05-03 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202123152554.8U Active CN216437071U (en) | 2021-12-14 | 2021-12-14 | Feedback circuit of switching power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216437071U (en) |
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2021
- 2021-12-14 CN CN202123152554.8U patent/CN216437071U/en active Active
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