A Seamless Mode Transition Scheme With DCM Compensation for AOT Buck Converter

Power-saving sleep mode (SM) is commonly employed to extend devices runtime in battery-powered buck converters. However, conventional mode transitions from active mode (AM) to SM rely on hard-switching actions for power-state conversion, which inject loop noise and may cause output glitches. This brief proposes a seamless power and gain transition (SPGT) scheme to achieve smooth transition from AM to SM and competitive conversion efficiency. Besides, the introduced DCM compensation effectively suppresses subharmonic oscillation to address the instability issue during SM operation. The proposed scheme is implemented in a 180 nm BCD process with a core scheme area of 0.07 μm². Test results show seamless transitions both AM-SM and PWM-PFM without any glitches. No subharmonic oscillation is observed during either steady-state or transient operation. The prototype achieves a peak efficiency of 96% and a 30 mV undershoot voltage and a 7 μs settling time under a 0.1-3A load step.