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CN-224233557-U - Flyback switching power supply control circuit

CN224233557UCN 224233557 UCN224233557 UCN 224233557UCN-224233557-U

Abstract

The utility model discloses a flyback switching power supply control circuit, and belongs to the technical field of power supply control. The power supply circuit is characterized by comprising an input end of external equipment connected with a primary side pin 1 of a transformer T1, wherein the primary side pin 1 of the transformer T1 is connected with an input end of a voltage-reducing sub-circuit, an output end of the voltage-reducing sub-circuit and 5, 6, 7 and 8 pins of a PWM controller U1 are simultaneously connected with a primary side pin 3 of the transformer T1, a sampling sub-circuit is connected in parallel between a pin 4 and a pin 5 of the transformer T1, a power supply sub-circuit is connected in series between a pin 4 and a pin 5 of the transformer T1, a first filtering sub-circuit is connected in series between a pin 6 and a pin 7 of the transformer T1, and a second filtering sub-circuit is connected in series between a pin 9 and a pin 10 of the transformer T1. The utility model meets the specific requirements of multiple devices, not only simplifies the circuit, but also reduces the occupation of space and the manufacturing cost.

Inventors

  • JIANG SHUAI
  • LENG JIAJI

Assignees

  • 镇江慧桥电气有限公司

Dates

Publication Date
20260512
Application Date
20250603

Claims (8)

  1. 1. The flyback switching power supply control circuit is characterized by comprising a primary side pin 1 of a transformer T1, wherein the primary side pin 1 of the transformer T1 is connected with an input end of a voltage reduction subcircuit, a primary side pin 3 of the transformer T1 is simultaneously connected with an output end of the voltage reduction subcircuit and 5, 6, 7 and 8 pins of a PWM controller U1, a sampling subcircuit is connected in parallel between a pin 4 and a pin 5 of the transformer T1, a power supply subcircuit is connected in series between the pin 4 and the pin 5 of the transformer T1, a first filtering subcircuit is connected in series between a pin 6 and a pin 7 of the transformer T1, and a second filtering subcircuit is connected in series between a pin 9 and a pin 10 of the transformer T1.
  2. 2. The flyback switching power supply control circuit according to claim 1, wherein the step-down sub-circuit comprises a resistor R1, a resistor R2, a capacitor C1 and a diode D1, one end of the resistor R1 is simultaneously connected with a pin 1 of the transformer T1 and one end of the capacitor C1, the other end of the resistor R1 is simultaneously connected with the other end of the capacitor and one end of the resistor R2, the other end of the resistor R2 is connected with the cathode of the diode D1, and the anode of the diode D1 is connected with a pin 3 of the transformer T1.
  3. 3. The flyback switching power supply control circuit according to claim 1, wherein the sampling sub-circuit comprises a resistor R4, a resistor R5 and a capacitor C5, one end of the resistor R4 is simultaneously connected with a pin 4 of the transformer T1 and an input end of the power supply circuit, the other end of the resistor R4 is simultaneously connected with one end of the capacitor R5, one end of the capacitor C5 and a pin 2 of the PWM controller U1, and the other end of the resistor R5 is simultaneously connected with the other end of the capacitor C5, a pin 3 of the PWM controller U1 and an output end of the power supply circuit.
  4. 4. The flyback switching power supply control circuit according to claim 1, wherein the power supply circuit resistor R3, the diode D2 and the capacitor C2, one end of the resistor R3 is connected to the pin 4 of the transformer T1, the other end of the resistor R3 is connected to the positive electrode of the diode D2, the negative electrode of the diode D2 is simultaneously connected to the positive electrode of the capacitor C2 and the pin 4 of the PWM controller U1, and the negative electrode of the capacitor C2 is connected to the pin 3 of the PWM controller U1 and grounded.
  5. 5. The flyback switching power supply control circuit of claim 1, wherein the first filter sub-circuit comprises a diode D4 and a capacitor C4, wherein the positive electrode of the diode D4 is connected to the pin 7 of the transformer T1, the negative electrode of the diode D4 is connected to the positive electrode of the capacitor C4, and the negative electrode of the capacitor C4 is connected to the pin 6 of the transformer T1.
  6. 6. The flyback switching power supply control circuit of claim 1 wherein the second filter sub-circuit comprises a diode D3 and a capacitor C3, wherein the positive electrode of the diode D3 is connected to the pin 10 of the transformer T1, the negative electrode of the diode D3 is connected to the positive electrode of the capacitor C3, and the negative electrode of the capacitor C3 is connected to the pin 9 of the transformer T1.
  7. 7. The flyback switching power supply control circuit of claim 1 wherein the transformer T1 is a TA24/4A type transformer.
  8. 8. The flyback switching power supply control circuit of claim 1 wherein the PWM controller U1 is a PN6795D type PWM controller.

Description

Flyback switching power supply control circuit Technical Field The utility model belongs to the technical field of power supply control, and particularly relates to a flyback switching power supply control circuit. Background Flyback switching power supplies are widely used for alternating current-to-direct current (AC/DC) conversion with electrical isolation between input and output. The flyback switching power supply is controlled by Pulse Width Modulation (PWM), and a high-frequency square wave signal is generated at the primary side of the transformer by controlling the closing and the conduction of the MOS tube. The transformer transmits the generated square wave signal to the secondary of the transformer in a magnetic field induction mode, and stable direct current output is obtained at the output end through the filtering rectification function of the diode and the capacitor. The flyback switching power supply is composed of a PWM controller, an MOS tube, a transformer, an output rectifying diode, an output filter capacitor and an output voltage sampling circuit. The traditional flyback switching power supply output voltage sampling circuit consists of an optocoupler, a voltage stabilizing source, a resistor, a capacitor and the like, and is complex in circuit, high in cost and large in PCB space occupied by a cloth board. Meanwhile, the traditional control circuit needs to be externally connected with an MOS tube, so that space and cost are increased. Disclosure of utility model The utility model aims to provide a flyback switching power supply control circuit which solves the problems existing in the prior art. According to the technical scheme, the flyback switching power supply control circuit comprises a primary side pin 1 of a transformer T1, wherein the primary side pin 1 of the transformer T1 is connected with an input end of a voltage reduction subcircuit, a primary side pin 3 of the transformer T1 is simultaneously connected with an output end of the voltage reduction subcircuit and 5, 6, 7 and 8 pins of a PWM controller U1, a sampling subcircuit is connected in parallel between a pin 4 and a pin 5 of the transformer T1, a power supply subcircuit is connected in series between the pin 4 and the pin 5 of the transformer T1, a first filtering subcircuit is connected in series between a pin 6 and a pin 7 of the transformer T1, and a second filtering subcircuit is connected in series between a pin 9 and a pin 10 of the transformer T1. Preferably, the step-down sub-circuit includes a resistor R1, a resistor R2, a capacitor C1 and a diode D1, wherein one end of the resistor R1 is simultaneously connected with a pin 1 of the transformer T1 and one end of the capacitor C1, the other end of the resistor R1 is simultaneously connected with the other end of the capacitor and one end of the resistor R2, the other end of the resistor R2 is connected with a cathode of the diode D1, and an anode of the diode D1 is connected with a pin 3 of the transformer T1. Preferably, the sampling sub-circuit includes a resistor R4, a resistor R5 and a capacitor C5, one end of the resistor R4 is simultaneously connected with the pin 4 of the transformer T1 and the input end of the power supply circuit, the other end of the resistor R4 is simultaneously connected with one end of the capacitor R5, one end of the capacitor C5 and the pin 2 of the PWM controller U1, and the other end of the resistor R5 is simultaneously connected with the other end of the capacitor C5, the pin 3 of the PWM controller U1 and the output end of the power supply circuit. Preferably, the power supply electronic circuit resistor R3, the diode D2 and the capacitor C2, one end of the resistor R3 is connected with the pin 4 of the transformer T1, the other end of the resistor R3 is connected with the positive electrode of the diode D2, the negative electrode of the diode D2 is simultaneously connected with the positive electrode of the capacitor C2 and the pin 4 of the PWM controller U1, and the negative electrode of the capacitor C2 is connected with the pin 3 of the PWM controller U1 and grounded. Preferably, the first filter sub-circuit diode D4 and the capacitor C4, wherein the positive electrode of the diode D4 is connected with the pin 7 of the transformer T1, the negative electrode of the diode D4 is connected with the positive electrode of the capacitor C4, and the negative electrode of the capacitor C4 is connected with the pin 6 of the transformer T1. Preferably, the second filter sub-circuit includes a diode D3 and a capacitor C3, where an anode of the diode D3 is connected to the pin 10 of the transformer T1, a cathode of the diode D3 is connected to an anode of the capacitor C3, and a cathode of the capacitor C3 is connected to the pin 9 of the transformer T1. Preferably, the transformer T1 is a TA24/4A type transformer. Preferably, the PWM controller U1 is a PN6795D type PWM controller. The flyback switching power supply control circu