With the rapid development of computer technology, electronic equipment and people working and living increasingly close relationship. Any electronic equipment without a reliable power supply, and power requirements of the increasingly high.
Switch regulated power supply to small size, light weight, high efficiency, stable performance, etc., and gradually replace the linear regulator power supply. However, most power are higher voltage and current output, the larger power. In this paper, the design of the output of the low-power 5V3A Switching Power Supply. First of all, the development of switching power supply, classification, and other aspects of the working principle is described and presented by a PWM modulator UC3843 features composed of AC / DC switching power supply, for which input and output, transformer and other circuit module done A Comparative Introduction, and the high-frequency transformer which has done a brief introduction.