提高UC3842控制开关电源精度的方法

Method of Improving the Control Precision of UC3842 in Switch Power Supply

在研制开关电源的工程实践中,为了提高基于UC3842的开关电源的控制精度以降低其电压调整率和负载调整率,对UC3842电压反馈输入端外围电路进行了研究,找到了提高其控制精度的有效且经济的方法。文中分析了影响UC3842控制的开关电源控制精度的关键因素,介绍了常规接法并指出了其存在的问题,以及改进接法和新型改进接法及其工作原理,比较了常规接法、改进接法和新型改进接法的优缺点,最后通过实验室测试证明了新型改进接法更能有效地降低电源电压调整率和负载调整率。

In engineering practice of switching power supply development, in order to improve the control precision of UC3842 based switching power supply and reduce it’s voltage regulation and regulation burden, we studied the peripheral circuit of UC3842’s voltage feedback pin and found an efficient and economic way to improve its control precision. Firstly the key factor that affects control precision of UC3842 controlled switching power supply is analyzed. Secondly the conventional circuit is described and its shortcomings are point out. Thirdly an improved circuit and a new type of improved circuit and their working principle are introduced. The advantages and disadvantages of conventional circuit, improved circuit and new type improved circuit are compared. Lastly, it is proved through laboratory test that the new type improved circuit is a better one in terms of less voltage regulation and regulation burden of switching power supply.