High performance voltage regulator for high step-down DC-DC conversion

The duty cycle of the conventional multi-phase buck converter becomes extremely small as the output voltage becomes lower and lower. This is a severe challenge as the switching frequency goes up. This paper presents a power circuit architecture to improve the efficiency of the laptop computer CPU Voltage Regulator (VR) by extending the duty cycle while improving the dynamic performance as well. The power circuit architecture is composed of an isolated full bridge current doubler rectifier converter in parallel with the buck converter. In this paper, the power circuit architecture, the proposed control scheme and the operation principle are discussed. A 9~19 V input, 1V/45A output, 450 kHz system has been designed and simulated using SABER. The simulation results shows improvement in the dynamic performance.