POWER ELECTRONICS HANDBOOK
Powering graphics processors from a 48-V bus ALEX LIDOW | EFFICIENT POWER CONVERSION
New converter topologies and power transistors promise to reduce the size and boost the efficiency of
Si-based 1/8-brick converter
supplies that will run next-generation AI platforms.
ARTIFICIAL
Intelligence (AI), gaming, cloud computing, and autonomous vehicles all employ the latest generation of graphics processors (GPUs) in lieu of CPUs. The reasoning is that GPUs offer higher computational density than traditional CPUs in terms of acquisition cost, size, and power requirements. The implications for power architecture seem clear; trends in vehicular power design are increasingly influenced by the power demands of electronics for autonomous systems. AI-based vehicles on the drawing boards generally use 48 V as the dominant voltage on the board with the GPU, and the final voltage must be somewhere around 1 V or less. Power levels are already around 1.5 kW and could soon hit 3 kW per GPU. What is less clear is the architecture necessary for getting from 48 V to 1 V at these power levels. There is a case for having isolation between the 48-V input and the point-of-load (POL) converters. It stems from two requirements. The first comes from the telecom industry where 48-V backup batteries supply a minus 48-V rail that must be isolated from the positive rails
VIN
A typical commercial eighthbrick converter based on silicon MOSFETs and its basic specs (top) and the EPC9115 eighthbrick converter using eGaN FETs for all power switches V along with its specs (bottom). IN
eGaN 1/8-brick converter
DESIGN WORLD — EE NETWORK
EPC — Power Electronics HB 02-19.indd 20
31 A
P OUT
300 W
η MAX
96.1%
VIN
38-55 V
VOUT
12 V
I OUT
42 A
P OUT
500 W
η MAX
96.7%
38-55 V 9.6 V
I OUT
31 A
P OUT
300 W
η MAX
96.1%
38-55 V
VOUT
12 V
I OUT
42 A
P OUT
500 W
η MAX
96.7%
Bottom view
Top view
20
9.6 V
I OUT
VOUT
VIN
38-55 V
VOUT
2 • 2019
eeworldonline.com | designworldonline.com
2/19/19 3:30 PM
