A 9 - 45V Input 2MHz 3-Switch ZVS Step-up / -down Hybrid Converter with 5x Volume Reduction

Abstract

This paper presents a 3-switch zero-voltage switching (ZVS) step-up /-down hybrid DC-DC converter for automotive applications. By having a flying capacitor, the proposed converter saves 1 auxiliary branch for establishing ZVS, and 1 power FET compared to the conventional buck-boost topology. With ZVS turn-on of all power FETs, the proposed converter is able to operate in the MHz range with high power efficiency in high input voltages via minimizing the switching loss. The flying capacitor further reduces the main inductor current in the step-down mode, significantly decreasing the inductor conduction loss. The proposed converter was validated using 100v e-mode GaN FETs with the on-chip gate drivers and control circuitry implemented in a HV 0.5µm BCD process. The proposed converter can support a wide input range from 9V to 45V with a maximum 48W output power, operate at 2MHz, and achieve peak power efficiencies of 98% and 96% in step-down and -up modes, respectively. The volume of external components in the proposed converter is also reduced by at least 5 times compared with the prior art.