Adaptive Window Control (AWC) Technique for Hysteresis DC-DC Buck Converters With Improved Light and Heavy Load Performance

Abstract

This paper presents a new adaptive window control (AWC) technique to adjust the hysteresis window to reduce the output ripple at heavy loads and keep the switching frequency higher than the acoustic frequency at light loads. Therefore, the driving capability and the power conversion efficiency of the hysteresis converter are improved at heavy loads. Besides, a new class AB current sensing circuit is also proposed to provide fast and accurate current sensing signal for achieving fast hysteresis window adjustment. Experimental results show that the proposed AWC technique not only reduces the output ripple smaller than 12 mV when load current is 800 mA to improve the power conversion efficiency but also keeps the switching frequency higher than acoustic frequency at light loads to avoid undesired noise.