Beyond 4 kW/in3 Power-Density for 48 V to 12 V Conversion using eGaN FETs in an LLC DC-DC Bus Converter

Increasing power demand of computing and datacenters operating from 48 V place a premium on high power density converters. To meet the extremely high power-density requirements, 3D packaging, converter efficiency, choice of components, and thermal design need to be considered and designed as a whole. Achieving high efficiency can be addressed by topology choice such as the LLC converter known for high power density and high efficiency, by using wide band gap (WBG) devices such as GaN FETs that are available in small chip scale packages, designing a custom transformer optimized for small size and performance and, understanding the contribution of parasitic elements to power conversion loss. This paper presents the design and evaluation of high power-density eGaN FET(R)-based 48 V to 12 V fixed conversion ratio LLC converter that fits within a volume defined by 23 × 17.5 × 8 mm with power density exceeding 4 kW/in3.