Synchronous spread spectrum circuit and method applied to program-controlled DC power supply

Abstract

The invention discloses a synchronous spread spectrum circuit applied to a program control direct-current power supply. The circuit is characterized by comprising three switching power supplies, each switching power supply is composed of an SG3525 control chip N1, one switching power supply serves as a main-frequency switching power supply, and the switching frequencies of the other switching power supplies are synchronized through the main-frequency switching power supply; meanwhile, the spread spectrum circuit is formed by an operational amplifier N2 and a triode V1, the current of the triode is changed through signal modulation so that the equivalent resistance of the triode can be regulated, and finally modulation of timing resistance of the SG3525 control chip N1 is achieved and the spread spectrum technology is realized. By the adoption of the synchronous spread spectrum technology, switching tubes of the multiple switching power supplies work at the same frequency, so that harmonic waves generated by the switching power supplies are within the same narrow-band range approximately, and finally, harmonic waves and noise caused by switching of a power tube can be filtered out through one narrow-band filter only.

Description

technical field [0001] The invention relates to the field of switching power supplies, in particular to a synchronous spread spectrum circuit and method applied to a program-controlled DC power supply. Background technique [0002] Since the last century, switching power supply has been developed and applied rapidly, and has been widely used in electronic equipment such as computers, communication equipment, control equipment, and household appliances. Compared with linear power supplies, switching power supplies have the characteristics of high efficiency, low power consumption, light volume, and small size. However, due to the use of switches, inverters and other circuits in the switching power supply, strong electromagnetic interference will be generated during the working process. These noise disturbances will pollute the surrounding electromagnetic environment and interfere with their normal work. Therefore, electromagnetic compatibility is a new problem faced in the ...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a synchronous spread spectrum circuit and method applied to a program-controlled DC power supply to solve the problem of electromagnetic interference signals in the switching power supply in the prior art

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