A Non-Isolated Single-Stage 48V-to-1V VRM with a Light Load Efficiency Improvement Technique

This paper presents a new non-isolated single-stage topology for a 48 V Voltage Regulator Module (VRM) using the Quadruple Step-Down Two-Phase Buck converter. The effective two-phase buck converter at the output can produce a very fast dynamic response. The input side switched-capacitor voltage divider increases the conversion ratio by four times compared to a standard buck converter. This converter also has high power density, reduced switch voltage and current stresses, reduced switching losses, and inherent phase current balancing ability. Few drawbacks of this converter include the inability of phase shedding and inefficient discontinuous conduction mode operation. To address the last problem a new light load efficiency improvement technique is proposed. The circuit operation, analysis, and experimental results from a 48V-to-1V, 60 A laboratory prototype are presented. Experimental results demonstrate the suitability of the converter in VRM applications and also verify the efficacy of the proposed light load efficiency improvement technique.