Overcurrent and overvoltage protection circuit for switching power supply

Abstract

The invention discloses an overcurrent and overvoltage protection circuit for a switching power supply. The protection circuit comprises a first resistor, a second resistor, a third resistor, a fourthresistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first capacitor, a second capacitor, a third capacitor, a first voltage stabilizing diode, a first triode, a second triode, a third triode, a fourth triode, a first diode, a second diode and a transformer auxiliary winding. The protection circuit has the advantages that a voltage detection circuit composed ofthe transformer auxiliary winding, the second diode and the eighth resistor is used for triggering the output overvoltage protection signal of a power supply control chip; a self-locking circuit composed of the second triode, the third triode, the fourth resistor, the sixth resistor and a tenth resistor is used for locking the output state of the switching power supply and protecting the switchingpower supply; the first triode and the tenth resistor are used for achieving overcurrent detection and overvoltage detection, periodic division is carried out, overcurrent detection is carried out when a first NMOS tube is switched on, and overvoltage detection is carried out after the first NMOS tube is switched off.

Description

technical field [0001] The invention relates to a switching power supply, in particular to an overcurrent and overvoltage protection circuit for the switching power supply. Background technique [0002] In the design process of industrial electronic products, the design and application of single-channel output switching power supply and multi-channel output switching power supply are very extensive. In the industrial environment, the switching power supply is susceptible to large interference, which affects the output of single or multiple loads. When the load has voltage imbalance, overvoltage, overcurrent, short circuit, etc., the switching power supply and load will be damaged. In order to solve this technical problem, it is necessary to protect the switching power supply from overcurrent and overvoltage, which is the core technical problem of switching power supply design. [0003] Most of the existing switching power supplies with overcurrent and overvoltage protection...

AI Technical Summary

Problems solved by technology

[0003] Most of the existing switching power supplies with overcurrent and overvoltage protection functions are switching power supply modules integrated with overcurrent and overvoltage protection circuits. However, such switching power supply modules are expensive, difficult to purchase, and have certain stability and reliability. Therefore, traditional switching power supplies are still used in many applications, so it is necessary to study the overcurrent and overvoltage protection circuits for traditional switching power supplies

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