Switching power supply control circuit

Abstract

The utility model relates to the technical field of switching power supply control circuits, provides a switching power supply control circuit, and aims to simplify circuit design, reduce failure rate and improve stability and reliability of a power supply. The circuit comprises a power supply special CV / CC feedback circuit IC1, a power supply feedback optocoupler OC1, a current-limiting resistor R2, filter capacitors DC1 and DC2, a power supply output end current-limiting resistor R1, power supply output end feedback resistors R3 and R4 and a current feedback resistor R5. The IC1 integrates voltage and current feedback functions, and the circuit structure is simplified. Through the characteristic that the voltage division values of the R3 and the R4 are increased along with the increase of the current, a droop type current-sharing circuit is realized, and the current-sharing control when a plurality of power supplies are connected in parallel for use is facilitated. The power supply has the advantages of short design period, wide application range, low failure rate, high power supply reliability and stability and the like, and is suitable for electronic equipment needing stable power supply output.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of switching power supply control circuit, specifically relates to a switching power supply control circuit. BACKGROUND

[0002] The switching power supply control circuit is a kind of circuit system for controlling the output voltage and current of switching power supply. It mainly monitors the output state of power supply, and adjusts the working state of power supply according to the preset voltage and current standard, to ensure the stability and reliability of power supply. The switching power supply control circuit is widely used in electronic equipment, and is crucial for ensuring the normal operation of equipment. The existing switching power supply control circuit has the following technical problems:

[0003] In order to realize the functions of current sharing, current limiting and voltage feedback circuit, the existing switching power supply feedback circuit often needs to adopt a variety of different circuit combinations. This leads to complex design process, and requires more time and effort to complete the design work. In order to realize the required functions, a variety of different components are often used in the prior art, which increases the material cost and also leads to the decline of the overall reliability and stability of the system. The existing switching power supply control circuit is more prone to failure, which affects the normal operation of the equipment. SUMMARY

[0004] To solve the problems in the background art, the utility model provides a switching power supply control circuit, which comprises a power supply special CV / CC feedback circuit IC1, a power supply feedback optocoupler OC1, a current limiting resistor R2 of OC1, a filter capacitor DC1, a filter capacitor DC2, a power supply output end current limiting resistor R1, a power supply output end feedback resistor R3, a power supply output end feedback resistor R4 and a current feedback resistor R5, wherein:

[0005] The power supply special CV / CC feedback circuit IC1 is provided with 1 pin, 1 pin is voltage feedback pin;2 pin, 2 pin is power supply end;3 pin, 3 pin is output end;4 pin, 4 pin is current feedback negative terminal;5 pin, 5 pin is current feedback positive terminal;Current limiting resistor R2 is used as series current limiting resistor, and is connected in series with power supply feedback optocoupler OC1;Power supply feedback optocoupler OC1 transmits feedback signal from output end to input end;DC1 is connected in parallel on input line;DC2 is connected in parallel on output line;Power supply output end current limiting resistor R1 is located at power supply output end;R3 and R4 are connected in parallel on output line, divide voltage and provide voltage feedback signal to 1 pin of IC1;Current feedback resistor R5 is used as series resistor, samples output current and sends into 5 pin of IC1;

[0006] The pin 1 of IC1 is connected with the voltage dividing point of R3 and R4, the pin 2 is connected with the input ground, the pin 3 is connected with the lower end of feedback photo-coupler OC1, the pin 4 is connected with the input ground, the pin 5 is connected with the output negative end through resistor R5, the current limiting resistor R2 is connected in series with the input end of feedback photo-coupler OC1, the lower end of feedback photo-coupler OC1 is connected with the pin 3 of IC1, the filter capacitor DC1 is connected in parallel with the input line for filtering the noise and interference in the input power supply, the filter capacitor DC2 is connected in parallel with the output line, the current limiting resistor R1 is connected in series with the output end of the power supply, the feedback resistor R3 and R4 are connected in parallel with the output line, the voltage dividing point of R3 and R4 is connected with the pin 1 of IC1, and the current feedback resistor R5 is connected in series with the output negative end for sampling the output current and sending into the pin 5 of IC1.

[0007] The utility model discloses has reached the beneficial effect that:

[0008] The utility model discloses adopt single power special CV / CC feedback circuit IC1 to realize the multiple function of current sharing, current limiting and voltage feedback circuit, and combine the optimization circuit element connection relation, further simplify circuit structure through current limiting resistor and power feedback photo-coupler series connection, filter capacitor parallel connection on input output line, utilize the characteristic that the voltage dividing value of R3 and R4 increases with the current increasing to realize the drooping current sharing circuit. The utility model has the characteristics of short design cycle, wide application range, low failure rate, high power reliability and stability and simple operation. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 It is the circuit structure schematic drawing of the utility model. DETAILED DESCRIPTION

[0010] The technical scheme in the utility model will be described clearly and completely below in combination with the drawings in the utility model, and in addition, the form of each structure recorded in the following implementation manner is only exemplified, and the utility model is not limited to each structure recorded in the following implementation manner, all other implementation manners obtained by the ordinary skill in the art without making creative labor belong to the range of protection of the utility model.

[0011] Referring to Figure 1 The utility model discloses a kind of switching power supply control circuit, including power special CV / CC feedback circuit IC1, power feedback photo-coupler OC1, current limiting resistor R2 of OC1, filter capacitor DC1, filter capacitor DC2, power output current limiting resistor R1, power output feedback resistor R3, power output feedback resistor R4 and current feedback resistor R5, wherein:

[0012] The power supply special CV / CC feedback circuit IC1 is provided with 1 pin, 1 pin is voltage feedback pin; 2 pin, 2 pin is power supply end; 3 pin, 3 pin is output end; 4 pin, 4 pin is current feedback negative end; 5 pin, 5 pin is current feedback positive end; current limiting resistor R2 is used as series current limiting resistor, which is connected with power supply feedback optocoupler OC1 in series; power supply feedback optocoupler OC1 transmits feedback signal from output end to input end; DC1 is connected in parallel on input line; DC2 is connected in parallel on output line; power supply output end current limiting resistor R1 is located at power supply output end; R3 and R4 are connected in parallel on output line, which divides voltage and provides voltage feedback signal to 1 pin of IC1; current feedback resistor R5 is used as series resistor, which samples output current and sends into 5 pin of IC1;

[0013] 1 pin of IC1 is connected with the voltage dividing midpoint of R3 and R4; 2 pin is connected with input ground; 3 pin is connected with lower end of feedback optocoupler OC1; 4 pin is connected with input ground; 5 pin is connected with output negative end through resistor R5; current limiting resistor R2 is connected in series at input end of power supply feedback optocoupler OC1; lower end of power supply feedback optocoupler OC1 is connected with 3 pin of IC1; filter capacitor DC1 is connected in parallel on input line, which is used to filter noise and interference in input power supply; filter capacitor DC2 is connected in parallel on output line; power supply output end current limiting resistor R1 is connected in series at power supply output end; power supply output end feedback resistor R3 and R4 are connected in parallel on output line, and voltage dividing midpoint of R3 and R4 is connected with 1 pin of IC1; current feedback resistor R5 is connected in series at output negative end, which is used to sample output current and send into 5 pin of IC1.

[0014] The circuit is a switching power supply control circuit, which realizes current sharing, current limiting and voltage feedback functions through a single IC, greatly simplifies circuit design, reduces design cycle and component types.

[0015] When the output voltage of the power supply changes, the voltage sampling resistor R3 and R4 will divide the output voltage.

[0016] The divided voltage is sent to the 1 pin of the power supply special CV / CC feedback circuit IC1. IC1 adjusts its output according to the feedback voltage to stabilize the output voltage, thereby realizing voltage feedback control. When there is current output from the power supply, a voltage drop will be generated on the output current limiting resistor R1. After sampling through the current feedback resistor R5, the voltage drop is sent to the 5 pin (current feedback positive end) of IC1. IC1 adjusts its output according to the current feedback signal to limit the output current and prevent overload, thereby realizing current limiting control.

[0017] As the output current increases, the voltage dividing value of R3 and R4 will also increase. Due to the change of the voltage dividing value, the voltage feedback circuit of IC1 will adjust the output voltage accordingly, so that the output voltage decreases with the increase of the current. This drooping type of voltage adjustment characteristic helps to achieve current sharing when multiple power supplies are used in parallel, i.e. each power supply shares the same current load.

[0018] Through the above working process, the novel switch power supply control circuit can efficiently realize voltage stabilization, current limitation and current sharing control, and provides powerful guarantee for stable operation of the switch power supply.

[0019] The above merely describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A switching power supply control circuit, characterized by comprising: The power supply special CV / CC feedback circuit IC1, the power supply feedback photocoupler OCl, the current limiting resistor R2 of OCl, the filter capacitor DC1, the filter capacitor DC2, the power supply output end current limiting resistor R1, the power supply output end feedback resistor R3, the power supply output end feedback resistor R4 and the current feedback resistor R5, wherein: The power supply special CV / CC feedback circuit IC1, the power supply feedback photocoupler OCl, the current limiting resistor R2 of OCl, the filter capacitor DC1, the filter capacitor DC2, the power supply output end current limiting resistor R1, the power supply output end feedback resistor R3, the power supply output end feedback resistor R4 and the current feedback resistor R5, wherein: The 1st pin of IC1 is connected to the midpoint of the voltage divider of R3 and R4; the 2nd pin is connected to the input ground; the 3rd pin is connected to the lower end of the feedback photocoupler OCl; the 4th pin is connected to the input ground; the 5th pin is connected to the output negative terminal through the resistor R5; the current limiting resistor R2 is connected in series at the input end of the power supply feedback photocoupler OCl; the lower end of the power supply feedback photocoupler OCl is connected to the 3rd pin of IC1; the filter capacitor DC1 is connected in parallel at the input line to filter out noise and interference in the input power supply; the filter capacitor DC2 is connected in parallel at the output line; the power supply output end current limiting resistor R1 is connected in series at the power supply output end; the power supply output end feedback resistors R3 and R4 are connected in parallel at the output line, and the midpoint of the voltage divider of R3 and R4 is connected to the 1st pin of IC1; the current feedback resistor R5 is connected in series at the output negative terminal to sample the output current and send it to the 5th pin of IC1.

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