A Zero-Voltage-Switching 3-Level Buck Converter Achieving 30% Loss Reduction at Light Load for USB-C Charger Applications

This paper described a proposed topology of Zero-Voltage-Switching 3-Level Buck (ZVS-3LB) converter with its fundamental operations and key characteristics. By inserting an auxiliary ZVS circuit with around 20% area overhead, the converter achieves maximum 30% loss reduction compared with a conventional 3-level buck converter when the output current is below 1.5 A. A peak efficiency of 92.4% is reached for 20 V/5 V conversion at 1 A load. As another significant benefit, ZVS operation allows the switching frequency to reach a multiple Mega-Hertz range as a result of low switching loss, making the topology a potential high power density candidate for USB-C charger applications.