MOSFETs redefine power density and efficiency in AI server power supplies

With the increasing power demands of AI processors, server PSUs must supply more and more power without surpassing the defined dimensions of the server racks. This is driven by a surge in energy demand of high-level GPUs, which may consume 2kW and more per chip by the end of the decade. These requirements and the emergence of increasingly demanding applications and the associated specific customer requirements have prompted Infineon Technologies AG to expand the development of SiC MOSFETs to voltages below 650V. The company is launching the new CoolSiC MOSFET 400V family, based on the second generation (G2) CoolSiC technology launched earlier this year. The new MOSFET portfolio was specially developed for usage in AI servers' AC/DC stage, complementing the company's recently announced PSU roadmap. The devices are also excellent for solar and ESS, inverter motor control, industrial and auxiliary power supplies (SMPS) and solid-state circuit breakers for residential buildings.

"Infineon offers an extensive portfolio of high-performance MOSFETs and GaN transistors to meet the demanding design and space requirements of AI server power supplies", said Richard Kuncic, head of the Power Systems Business Line at Infineon. "We are committed to supporting our customers with advanced products such as the CoolSiC MOSFETs 400 V G2 to drive the highest energy efficiency in advanced AI applications."

The new family offers ultra-low conduction and switching losses when compared to existing 650V SiC and Si MOSFETs. Implemented in a multi-level PFC, the AC/DC stage of the AI Server PSU can achieve a power density of more than 100W/in³ and is proven to reach 99.5% efficiency. This is an efficiency improvement of 0.3 percentage points over solutions using 650V SiC MOSFETs. Also, the system solution for AI Server PSUs is completed by implementing CoolGaN transistors in the DC-DC stage. With this combination of high-performance MOSFETs and transistors, the power supply can deliver more than 8kW with an increase in power density by a factor of more than three compared to current solutions.

The new MOSFET portfolio comprises ten products: five R DS(on) classes from 11 to 45mOhm in Kelvin-source TOLL and D²PAK-7 packages with .XT package interconnect technology. The drain-source breakdown voltage of 400V at T vj = 25C makes them excellent for use in two- and three-level converters and for synchronous rectification. The components provide high robustness under harsh switching conditions and are 100% avalanche-tested. The highly robust CoolSiC technology, in combination with the .XT interconnect technology allows the devices to cope with power peaks and transients caused by sudden changes in the power requirements of the AI processor. The connection technology and a low and positive RDS(on) temperature coefficient allow excellent performance under operating conditions with higher junction temperatures.

Engineering samples of the CoolSiC MOSFET 400V portfolio are now available.