Design and Implementation of the UC3842 Multiple-Output Flyback Switching Power

本文以电流型控制芯片UC3842为核心设计了一种新型多路输出反激式开关电源，该电源有5路稳定的直流电压输出。本文介绍了电流型PWM控制芯片UC3842的原理和特性，分析了该开关电源的设计原理、工作过程和各个组成模块的主要功能，包括反激式隔离变压器的磁芯选择、占空比的计算、原边及各路输出的匝数的确定，同时设计了EMI抑制电路，保证了开关电源的电磁兼容性和安全性需求。实验结果表明：所设计的开关电源稳定性好，纹波少，电压调整率高、电磁兼容性好等特点，具有很高的应用价值。 With the current-mode control chip UC3842 as its core, a new multiple-output flyback switching power sup- ply is designed, which has five stable DC voltage outputs. The principle and characteristic of the control chip UC3842 is introduced, the design principle and work process and main function of the various components of the module are analysed, including the selection of the flyback isolation transformer magnetic core and duty ratio calculation and the determination of the number of the winding turns. The EMI suppression circuitry is designed in order to ensure the re- quirements of electromagnetic compatibility and security. The experimental results show that the designed switching power supply works steadily with less ripple, high voltage adjustment rate, good electromagnetic compatibility, so it has a high application value.