Switching power supply is a kind of power supply that uses modern power electronics technology to control the ratio of time when the switch is turned on and off, and maintains a stable output voltage. The switching power supply is generally composed of a pulse width modulation (PWM) control IC and a MOSFET. Compared with linear power supplies, switching power supplies increase in cost as output power increases, but the growth rates vary. The linear power supply cost is higher than the switching power supply at a certain output power point, which is called the cost reversal point. With the development and innovation of power electronics technology, switching power supply technology is also constantly innovating. This cost reversal point is increasingly moving to the low output power end, which provides a broad space for development of switching power supplies.
The high frequency of switching power supply is the direction of its development, and the high frequency makes the switching power supply miniaturized.
The application of switching power supplies to a wider range of applications, especially in high-tech applications, has promoted the miniaturization and portability of high-tech products. In addition, the development and application of switching power supplies are of great significance in terms of energy conservation, resource conservation and environmental protection. The power electronics used in switching power supplies are mainly diodes, IGBTs and MOSFETs. SCR has a small number of applications in the switching power supply input rectifier circuit and soft start circuit. The GTR drive is difficult, the switching frequency is low, and it is gradually replaced by IGBT and MOSFET.