降压型转换器的下功率管过流保护电路设计

An Integrated Over-current Protection for Low-side Switch in Buck Converter

基于降压型DC-DC转换器结构,设计了一个在下功率管导通时预防过流情况发生的保护电路。首先阐述了下功率管过流保护电路设计的必要性,并从降压型DC-DC的电路原理上分析了针对下功率管的过流保护机制。接着详细介绍了该电路的工作原理和实现方式,在此基础上重点论述了一个运用在保护电路中的结构简单、检测准确的采样电路的设计。利用CSMC0.6μmBCD工艺,对该过流保护电路进行了仿真,在设置的仿真条件下,电路的采样误差不超过10%,响应时间约为280ns。仿真结果显示,整个电路设计具有响应快速、保护范围可灵活设置等特点。

A protection circuit is presented to keep Buck DC-DC converter＇s low-side switch from over-current circumstance. Firstly, the necessity of over-current protection circuit for low-side switch is discussed and its mechanism is analyzed according to theory of the Buck DC-DC converter. Then a simple and accurate sensing circuit used for over-current protection is designed, which is based on the detailed introduction about the working principle of the blocks and circuits. Using CSMC 0.6 la m BCD process, simulations show that the measured error is less than 10%, and the response time is about 280ns. The simulating results show that fast response and adjustable protection range are main features of the design.