A Two-Step Down Converter Based on Pseudo 4-Phase Mutual Operation for 48-to-1 Conversion

This paper proposes a two-step down converter based on Pseudo 4-Phase Mutual Operation (P4MO) that uses inductors and coupled inductors to regulate output voltage (V_OUT). By doubling the inductor current slew rate, the design reduces the intermediate capacitor (C_INT) at V_INT by nearly 50%. Additionally, conduction losses in the dual-output triple step-down (DOTS) input stage are reduced by approximately 30%. Moreover, a delayed feedback PWM technique further reduces the V_INT ripple by about 20%. An integrated soft turn-off circuit minimizes voltage variations at V_OUT to less than 2 mV during phase shedding. Experimental results validate the design’s performance, showing a peak efficiency of 93.1%, undershoot of 106 mV with a recovery time of 1.9 μs for a load step transition from 1 A to 20 A, and a transient performance of 5.58 mV/A.