A High-Efficiency Double Step Down Converter With Dual-Mode Control and Seamless Mode Transition In A Wide Load Current Range

This paper presents a high-efficiency double step-down power converter with a dual-mode control scheme in a wide load range. A voltage-mode control scheme with an instant Tzcd and
$\text{Tsw}/2$
mirror is employed in discontinuous conduction mode (DCM). It avoids negative inductor current in DCM and improves efficiency in light load with minimized voltage ripples. Meanwhile, a current-mode control scheme is used in continuous conduction mode (CCM), sharing a single feedback controller and
$\text{Tsw}/2$
mirror controller with DCM. The inherent time difference of detection cycles between DCM and CCM is used to realize a seamless dual-mode transition. The converter is designed with a conversion for 12.0 V to 1.0 V at 1-MHz switching frequency, based on a
$0.15-{\mu m}$
high-voltage BCD process. The simulation shows that a power efficiency of 79.8% is achieved with a dual-mode control under a 200-mA current load, which is the 7.2% higher than the counterpart without dual-mode control. Moreover, the power efficiency is above 76.5% even at a 50mA load with an improvement of 14.1%.