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CN-224218289-U - Flyback switching power supply

CN224218289UCN 224218289 UCN224218289 UCN 224218289UCN-224218289-U

Abstract

The utility model relates to the technical field of switching power supplies, in particular to a flyback switching power supply, which comprises a PWM control chip U1, an input loop for inputting voltage, an output loop for outputting voltage, a feedback loop and an overload stable hiccup protection circuit, wherein the input loop is connected with the PWM control chip U1, the input loop and the output loop realize output voltage regulation through a transformer, the feedback loop is also connected with the output loop and is used for feeding back the output voltage to the PWM control chip U1, and the PWM control chip U1 is also respectively connected with an input voltage feedback compensation circuit and an overload stable hiccup protection circuit.

Inventors

  • LIU SHAOQIN
  • LI BINCHENG
  • CHEN SHANKANG

Assignees

  • 深圳蜂芒新能源科技有限公司

Dates

Publication Date
20260508
Application Date
20250530

Claims (8)

  1. 1. The flyback switching power supply comprises a PWM control chip U1 and is characterized by comprising an input loop for inputting voltage, wherein the input loop is connected with the PWM control chip U1, the flyback switching power supply further comprises an output loop for outputting voltage, the input loop and the output loop are used for realizing output voltage regulation through a transformer, the output loop is further connected with a feedback loop, the feedback loop is used for feeding the output voltage back to the PWM control chip U1, and the PWM control chip U1 is further connected with an input voltage feedback compensation circuit and an overload stable hiccup protection circuit respectively.
  2. 2. The flyback switching power supply of claim 1 wherein the PWM control chip U1 is one of the types UC2842, UC2843, UC2844, UC2845, UC3842, UC3843, UC3844, and UC 3845.
  3. 3. The flyback switching power supply of claim 2, wherein the input voltage feedback complementary circuit comprises a resistor R2, a resistor R3 and a capacitor C1, one end of the resistor R2 is connected to the input voltage VIN, the other end of the resistor R2 is connected to the third pin of the PWM control chip U1, one end of the resistor R3 is connected to the third pin of the PWM control chip U1, the other end of the resistor R3 is grounded, and the capacitor C1 is connected in parallel with the resistor R3.
  4. 4. The flyback switching power supply of claim 2, wherein the overload stabilization hiccup protection circuit comprises a triode Q1 and a triode Q2, wherein a base electrode of the triode Q1 is connected with one end of a resistor R4, the other end of the resistor R4 is connected with a first pin of a PWM control chip U1, a resistor R5 is connected in series between the base electrode and an emitting electrode of the triode Q1, a capacitor C3 is connected in parallel with two ends of the resistor R5, a capacitor C4 is connected in series between the emitting electrode and a collecting electrode of the triode Q1, the emitting electrode of the triode Q1 is grounded, a collecting electrode of the triode Q1 is connected with one end of a resistor R6, the other end of the resistor R6 is connected with a base electrode of the triode Q2, a resistor R7 is connected in series between the base electrode and the collecting electrode of the triode Q2, a collector electrode of the triode Q2 is connected with a reference voltage VREF, and the emitting electrode of the triode Q2 is connected with a third pin of the PWM control chip U1.
  5. 5. The flyback switching power supply of claim 2, wherein the input loop comprises a capacitor C11, a transformer primary winding T19-A, MOS, a resistor R1, one end of the transformer primary winding T19-a is connected to an input voltage VIN, the other end of the transformer primary winding T19-a is connected to a drain electrode of a MOS transistor Q10, an anode of the capacitor C11 is connected to the input voltage VIN, a cathode of the capacitor C11 is grounded, a gate of the MOS transistor Q10 is connected to one end of the resistor R10, the other end of the resistor R10 is connected to a sixth pin of a PWM control chip U1, a source of the MOS transistor Q10 is connected to a third pin of the PWM control chip U1, the source of the MOS transistor Q10 is further connected to one end of the resistor R1, and the other end of the resistor R1 is grounded.
  6. 6. The flyback switching power supply of claim 2 wherein the output loop comprises a transformer secondary winding T19-B, one end of the transformer secondary winding T19-B is connected to an anode of a diode D1, a cathode of the diode D1 is a voltage output VOUT end, a cathode of the diode D1 is connected to an anode of a capacitor C12, a cathode of the capacitor C12 is connected to the other end of the transformer secondary winding T19-B, and a cathode of the capacitor C12 is grounded.
  7. 7. The flyback switching power supply of claim 6, wherein the feedback loop comprises an optocoupler OT1, a first pin of the optocoupler OT1 is connected with a cathode of a diode D1, the first pin of the optocoupler OT1 is sequentially connected in series with a resistor R9 and a resistor R8 and then grounded, a second pin of the optocoupler OT1 is connected with a cathode of a three-terminal voltage-stabilizing chip U2, an anode of the three-terminal voltage-stabilizing chip U2 is grounded, a reference pin of the three-terminal voltage-stabilizing chip U2 is connected with a non-grounded end of the resistor R8, a fourth pin of the optocoupler OT1 is connected in series with a resistor R11 and then connected to a first pin of a PWM control chip U1, and a third pin of the optocoupler OT1 is grounded.
  8. 8. The flyback switching power supply according to claim 2, further comprising a power supply loop for supplying power to the PWM control chip U1, wherein the power supply loop comprises a resistor R12, one end of the resistor R12 is connected to the input voltage VIN, the other end of the resistor R12 is connected to the seventh pin of the PWM control chip U1, the other end of the resistor R12 is further connected to the cathode of a diode D2, the anode of the diode D2 is connected to one end of the transformer secondary winding T19-C, the other end of the transformer secondary winding T19-C is grounded, the cathode of the diode D2 is further connected to one end of a capacitor C2, and the other end of the capacitor C2 is grounded.

Description

Flyback switching power supply Technical Field The utility model relates to the technical field of switching power supplies, in particular to a flyback switching power supply. Background The flyback switching power supply is a power supply which utilizes the modern electronic power technology to control the time ratio of switching on and switching off of a switching tube and maintain stable output voltage, and generally consists of a Pulse Width Modulation (PWM) control IC and a MOSFET, and plays an important role in the field of medium and small power by virtue of the advantages of simple structure and low cost. However, the flyback circuit of the existing PWM control IC generally adopts single-voltage loop control, the control mode of the output current is simpler, the capacitor of the current pin of the control IC is charged through the current sampling resistor when the single output is overloaded, when the input voltage range is wider, the problem that the circuit cannot stably enter hiccup protection is easy to exist, the difference between the overcurrent points of the input high voltage and the input low voltage is larger, and the existence of the two problems can indirectly lead to overheat failure of the circuit. Disclosure of utility model The utility model aims to provide a flyback switching power supply which can stably enter a hiccup protection state when in overload and has a fixed overload protection point in a full input voltage range. In order to achieve the above purpose, the present utility model provides the following technical solutions: In a first aspect, the utility model provides a flyback switching power supply, which comprises a PWM control chip U1, an input loop and an output loop, wherein the input loop is used for inputting voltage, the input loop is connected with the PWM control chip U1, the output loop is used for outputting voltage, the input loop and the output loop realize output voltage regulation through a transformer, the output loop is also connected with a feedback loop, the feedback loop is used for feeding the output voltage back to the PWM control chip U1, and the PWM control chip U1 is also respectively connected with an input voltage feedback compensation circuit and an overload stabilization hiccup protection circuit. With reference to the first aspect, optionally, the PWM control chip U1 is one of UC2842, UC2843, UC2844, UC2845, UC3842, UC3843, UC3844, and UC 3845. With reference to the first aspect, optionally, the input voltage feedback complementary circuit includes a resistor R2, a resistor R3, and a capacitor C1, where one end of the resistor R2 is connected to the input voltage VIN, the other end of the resistor R2 is connected to the third pin of the PWM control chip U1, one end of the resistor R3 is connected to the third pin of the PWM control chip U1, the other end of the resistor R3 is grounded, and the capacitor C1 is connected in parallel with the resistor R3. In combination with the first aspect, optionally, the overload stabilization hiccup protection circuit includes a triode Q1 and a triode Q2, a base electrode of the triode Q1 is connected with one end of a resistor R4, the other end of the resistor R4 is connected with a first pin of a PWM control chip U1, a resistor R5 is connected in series between the base electrode and an emitter electrode of the triode Q1, two ends of the resistor R5 are connected with a capacitor C3 in parallel, a capacitor C4 is connected in series between the emitter electrode and a collector electrode of the triode Q1, the emitter electrode of the triode Q1 is grounded, a collector electrode of the triode Q1 is connected with one end of a resistor R6, the other end of the resistor R6 is connected with a base electrode of the triode Q2, a resistor R7 is connected in series between the base electrode and the collector electrode of the triode Q2, a collector electrode of the triode Q2 is connected with a reference voltage VREF, and an emitter electrode of the triode Q2 is connected with a third pin of the PWM control chip U1. With reference to the first aspect, optionally, the input circuit includes a capacitor C11, a transformer primary winding T19-A, MOS, a resistor R1, one end of the transformer primary winding T19-a is connected to the input voltage VIN, the other end of the transformer primary winding T19-a is connected to the drain of the MOS transistor Q10, the positive electrode of the capacitor C11 is connected to the input voltage VIN, the negative electrode of the capacitor C11 is grounded, the gate of the MOS transistor Q10 is connected to one end of the resistor R10, the other end of the resistor R10 is connected to a sixth pin of the PWM control chip U1, the source of the MOS transistor Q10 is connected to a third pin of the PWM control chip U1, the source of the MOS transistor Q10 is also connected to one end of the resistor R1, and the other end of the resistor R1 is grounded. With reference to the firs