Design and Implementation of Switched‐Capacitor‐Buck Converter With Improved Light Load Efficiency

ABSTRACT The intermediate bus power architecture applied in data centers usually adopts a two‐stage DC– DC conversion scheme from 48 V bus voltage. In order to further improve the conversion efficiency of the two‐stage circuit while reducing the size and cost of the circuit output capacitor, the overall system control with charge COT control scheme is utilized in this paper, not only can achieve higher efficiency under light load, while the output capacitor in the use of smaller, lower cost ceramic capacitors. Moreover, the existence of the subharmonic oscillation phenomenon is omitted. The experimental results show that the proposed control scheme can significantly improve the light‐load efficiency of the two‐stage circuit, and at the same time, the output ripple of the ceramic capacitor can be controlled to about 20 mV (0.4%) without subharmonic oscillation at an output load point voltage of 5 V.