关键词: 降压型直流转直流变换器, 自举电容, 软启动

Abstract: Step-down dc-dc converter names BUCK and is used more widely than other converters. In order to make BUCK work properly, peripheral devices, like output voltage divider resistance, input and output filter capacitor and output filter inductance are needed. Some buck circuits also need boost capacitor, compensation devices and soft start capacitor, and so on. The above devices determine buck’s performance. Make an analysis about buck converter’s principle and internal structure firstly. Then, how to calculate the parameters of external devices and simulation are given. It shows that the result is the same as theoretical value.

Key words: step-down dc-dc converter, boost capacitor, soft start