Single-stage isolated 48V-to-1.8V point-of-load converter utilizing an impedance control network for wide input range operation

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 through a combination of stacked inverters, a 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 the three inductors of the ICN into a single integrated magnetic structure. A design methodology based on 3D finite-element-analysis is employed to optimize the magnetic components of the proposed ICN converter. A prototype 90-W ICN converter utilizing 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 88.7% and maintains efficiencies above 87.6% across its nearly 2:1 input voltage range, and above 86.6% across a 10:1 output power range.