Single-stage isolated 48V-to-1.8V point-of-load converter utilizing an impedance control network and integrated magnetic structures

This paper introduces a single-stage isolated 48V-to-1.8V point-of-load converter based on the impedance control network (ICN) resonant converter architecture. This point-of-load ICN converter achieves large step-down while maintaining high efficiency across a wide range of input voltage and output power. Large step-down is achieved using a novel immittance network transformer and a resonant current-doubler rectifier. High efficiency is achieved by utilizing the ICN architecture, which enables zero-voltage and near-zero-current switching across wide operating ranges. The power density of the converter is enhanced by combining its magnetic components into two integrated magnetic structures: one implementing the three inductors of the ICN using two coupled windings, and the other implementing the immittance network transformer and current-doubler magnetics on a common core. A systematic methodology is introduced to design and optimize the proposed ICN converter. A prototype 90-W ICN converter utilizing PCB-integrated 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 prototype ICN converter achieves a peak efficiency of nearly 90%, and maintains greater than 87.9% efficiency across its nearly 2:1 input voltage range.