MLB-PoL: A High Performance Hybrid Converter for Direct 48 V to Point-of-Load Applications

There is an increasing need for more efficient power conversion from 48 V
_dc
to point-of-load (PoL) applications in datacenters. This work presents a new hybrid converter with Multi-Level Binary (MLB) voltages on the flying capacitors that is well-suited for PoL applications with very high conversion ratios. The proposed MLB-PoL converter can be viewed as an 8-to-1 multi-phase doubler switched-capacitor (SC) converter merged with a two-phase interleaved buck converter. Compared to other two-phase hybrid SC topologies, multi-phase operation can help achieve higher conversion ratio in the SC stage with an equal or fewer number of components, and thus reduce the switch and inductor stress of the following buck stage. In addition, the output inductors in the proposed topology benefit from a frequency multiplication effect similar to that of the flying capacitor multilevel (FCML) converter. This can help further reduce the inductor size without increasing the switching frequency. A 48 V to 2.5-1.0 V converter prototype with 65 A output current was built and tested. At 48 V to 2 V, the prototype achieved 95.1% peak efficiency (94.3% including gate drive loss) and 395 W/in
³
power density.