A Fully-Interleaved Stacked-Half-Bridge Single-Stage 48V-1V Voltage Regulator

In the architecture of point-of-load power supply in data center power system, 48V bus is gradually replacing 12V bus due to its lower conduction loss, and the 48V-1V single-stage high current high step-down converter has become a promising candidate for the third power stage. This paper compares the characteristics of single-stage multi-phase parallel and multi-element stacked structures in improving voltage step-down ratio and current carrying capacity. A fully interleaved stacked-half-bridge structure is proposed. The influence of the number of stacked elements on converter characteristics is discussed, and the optimal parameter configuration is found. Compared with the conventional solution, the proposed structure achieves a lower transformer turn ratio. Planar magnetic components are employed to reduce the height of the prototype, and a planar coupled inductor with five-leg core is proposed to achieve coupling of all output inductors. A 48V-1V/100A prototype was built, operating at 300kHz with a peak efficiency of 86.2%.