With the rapid development of power electronic technology and switching industry, power electronic equipment and people's work and life increasingly close relationship, and electronic equipment can not be separated from reliable power supply, into the 1980s computer power fully realized switching power supply, the first to complete the computer power generation, into the 1990s switching power has entered a variety of electronic, electrical equipment field, SPC switch, communication, electronic testing equipment power supply, control equipment power supply has been widely used in switching power supply, but also promote the rapid development of switching power technology. Switching power supply is the use of modern power electronics technology, control switching transistor on and off time ratio, maintain stable output voltage of a power supply, switching power supply is generally composed of pulse width modulation (PWM) control IC and MOSFET. Compared with linear power supply, the cost of switching power supply and linear power supply increases as the output power increases, but at different rates. The cost of linear power supply is higher than that of switching power supply at a certain output power point, which is the cost reversal point. With the development and innovation of power electronics technology, switching power supply technology is constantly innovated, and the cost reversal point is increasingly moving to the low output power end, which provides a wide range of development space for switching power supply.

The high frequency of switching power supply is the direction of its development. The high frequency makes the switching power supply miniaturized, and makes the switching power supply enter a wider range of application fields, especially in the field of technical application, and promotes the miniaturization and portability of technical products. In addition, the development and application of switching power supply is of great significance in saving energy, saving resources and protecting environment.