작은 출력 전압 리플과 고정된 스위칭 주파수를 갖는 히스테리틱 벅 변환기 설계

초록

An efficient fast response hysteretic buck converter suitable for mobile application is proposed. The problem of large output ripple voltage that conventional hysteretic converter has is improved by adding low pass filter, and switching frequency changed with load condition is fixed by using PLL structure. The circuits are implemented using Dongbu 0.35um BCDMOS process. The settling time is maximum 5.5us and output voltage overshoot is 21mV when load current changes from 500mA to 1A. The efficiency is 91~95% under 500mA~1A load condition and output voltage is 1.2V with 3.55mV ripple voltage.