A 48 V Input 0.75 V Output DC-DC Converter Power Block for HPC Systems and Datacenters (invited paper)

The IBM Power Block is a high power density, low cost 48 V input DC-DC converter, designed to source up to 107 A of continuous output current to processors in high performance computing (HPC) and datacenter servers. Peak efficiency for a 0.75 V output is 90.6% at 45 A and 85.1% at 107 A. An active clamp forward converter (ACFC) architecture uses a pair of primary FETs and a pair of secondary FETs, separated by a planar transformer. A custom timing chip provides four gate timing signals, whose delays can be stored in internal fuses or set through a serial interface. Transformer and inductor magnetics are integrated into a single ferrite structure that allows induced electro motive forces (EMFs) to cancel, thereby providing near zero output current ripple at 0.75 V and low ripple 0.5 V to 1.0 V. Designed for 1 U servers, the Power Block has a 13 mm x 16 mm footprint and a 19 mm height. The electrical output contact’s flat top permits mounting a heat sink or cold plate.