A Buck Dc-Dc Converter With A Novel Pwm/Pfm Hybrid-Mode Auto-Change Technique

A novel PWM/PFM hybrid-mode auto-change technique for buck DC-DC converter is proposed. The proposed technique utilizes the comparator propagation delay to decide the mode changing point without adding complicated PMW/PFM hybrid-mode controller. The proposed concept enables compact and simple implementation of hybrid-mode buck DC-DC converter. Simulation results show that the buck DC-DC converter can achieve seamless transition between PWM and PFM mode. The maximum efficiency of PWM and PFM mode are up to 97% and 94% respectively.