Infineon / Switched Capacitor Converter Up to 99 Percent Efficiency at 600 W

DESIGN&ELEKTRONIK-Redakteur Ralf Higgelke im Gespräch mit Eric Persson (rechts), Lead Principal, Global GaN Applications Engineering bei Infineon, über den neuen ZSC-Wandler.
DESIGN&ELEKTRONIK editor Ralf Higgelke talks to Eric Persson (right), Lead Principal, Global GaN Applications Engineering at Infineon, about the new ZSC converter.

Infineon has developed a bus converter in a soft-switching hybrid switched-capacitor topology. This converts a 48 V input into a bus voltage of 12 V in order to supply processors and memory systems in datacenter via subsequent point-of-load converters.

Hyperscale datacenters use a multi-stage architecture to power CPUs, GPUs, SoCs, ASICs and memory devices. First, the AC mains voltage is converted to 48 V DC in a front-end power supply unit, which is then distributed in the server rack. Each rack then contains a so-called bus converter, which converts the 48 V into a lower bus voltage – usually 12 V – which is then distributed at PCB level.

Infineon has now developed a reference design based on a soft-switching hybrid switched-capacitor topology for such bus converters. At PCIM Europe 2019, we talked to Eric Persson, Lead Principal, Global GaN Applications Engineering at Infineon Technologies, to learn more about this.

This so-called ZSC converter (Zero-voltage-switching Switched-capacitor Converter) uses microcontrollers, drivers and switches from Infineon. This includes coordinated components such as MOSFETs from the OptiMOS 5 (25 V) and OptiMOS 6 series (40 V) as well as gate driver ICs from the EiceDRIVER 2EDi family. The XMC microcontroller family completes the ZSC converter.

Depending on system requirements, the converter could be implemented as a module or directly on the motherboard. The topology allows bidirectional power transmission as well as different transmission ratios (2:1, 4:1, 6:1, 8:1, 10:1, 12:1) when implemented with the same components. In a 4:1 configuration, the 600W ZSC converter can achieve a power density of 121W/cm² (780W/inch²) and an efficiency of up to 99 percent. Due to the flat efficiency curve and high thermal performance, the same design can provide up to 1 kW.

The ZSC board is available on request. Further information is available at