A power supply module is a power supply that can be directly mounted on a printed circuit board. ) and other digital or analog loads. Typically, such modules are referred to as load (POL) power supply systems or point-of-use power supply systems (PUPS). Due to the many advantages of the modular structure, modular power supplies are widely used in switching equipment, access equipment, mobile communications, microwave communications, optical transmission, routers and other communications fields, automotive electronics, aerospace, etc. Typically, such modules are referred to as load (POL) power supply systems or point-of-use power supply systems (PUPS). Due to the many advantages of the modular structure, modular power supplies are widely used in switching equipment, access equipment, mobile communications, microwave communications, optical transmission, routers and other communications fields, automotive electronics, aerospace, etc. Especially in recent years, due to the rapid development of data services and the continuous promotion of distributed power supply systems, the growth rate of modular power supply has exceeded that of primary power supply. The module power supply has isolation function, strong anti-interference ability, and has its own protection function, which is convenient for integration. With the extensive use of semiconductor technology, packaging technology and high-frequency soft-switching, the power density of module power supply is increasing, the conversion efficiency is getting higher and higher, and the application is getting simpler and simpler.