A design of flyback switched-mode power supply with softswitching using the UC3842 controller

Abstract

The flyback switched-mode power supply is widely used in various electrical equipments due to its high efficiency and small size. This article is used UC3842 as the core control chip to design a flyback switched-mode power supply. The design includes the input of 36∼48V and an output of 12V and introduces a soft-switching design. The trigger signal of the next cycle arrives after the switching voltage drops to zero and realizes zero voltage switching (ZVS) to reduce switching losses. At the same time, single-ended flyback switching circuits, feedback circuits, and RCD clamp circuits are designed. The simulation result is shown the accuracy for the output voltage is within 1.08%, as well as the ripple factor is below 0.011%.