High-Performance Single-Stage Isolated 48V-to-1.8V Point-of-Load Converter Utilizing Impedance Control Network and Distributed Transformer

This paper introduces a high-efficiency high-power-density single-stage isolated 48V-to-1.8V point-of-load (PoL) converter. This converter achieves large step-down with high efficiency using a distributed transformer and a resonant immittance network. The high efficiency is maintained across variations in input voltage and output power using an impedance control network (ICN) based high-frequency inverter structure, which enables zero-voltage and near-zero-current switching across wide operating ranges. High power density is achieved by utilizing rectifier phase-shift control that eliminates the need for bulky electrolytic capacitors, and by implementing the converter's inductors and transformer as planar integrated magnetic structures. The design of the magnetic structures is optimized using 3D finite-element analysis. A prototype 90-W 1-MHz PoL converter utilizing PCB-integrated planar magnetics, designed to operate over an input voltage range of 36 V to 60 V and an output voltage of 1.8 V is built and tested. The prototyped converter achieves a peak efficiency of 92.6%, maintains full-power efficiencies above 88.9% across its nearly 2:1 input voltage range, and achieves a power density of 314 W/in 3 .