Infineon takes CoolMOS to generation 7; halves switching losses

May 25, 2015 // By Graham Prophet
Infineon Technologies’ C7 series superjunction (SJ) MOSFETs is a 600 V series that claims 50% reduction in turn-off losses compared to the CoolMOS CP, offering a GaN-like level of performance in PFC, TTF and other hard-switching topologies. The company also presents it as a transition to forthcoming GaN devices.

The CoolMOS C7 claims an industry first by delivering an area-specific on resistance (*A) of 1Ω per mm², extending Infineon’s portfolio of products with lowest RDS(ON) per package to support customer efforts to further increase power density. This CoolMOS series features ultra-low switching losses and targets high power SMPS applications such as server, telecom, solar and industrial designs.

Efficiency and TCO-driven (total cost of ownership – that is, factoring in lifetime electricity-bill-savings) applications such as hyperscale data centers and telecom base stations benefit from the switching loss reduction. Efficiency gains of 0.3% to 0.7% in PFC and 0.1% in LLC topologies can be achieved, leading to significant total cost of ownership benefits. In the case of a 2.5 kW server PSU, for example, using C7 600V MOSFETs can result in energy cost reductions of around 10% for PSU energy loss.

In BoM and cost driven designs such as enterprise servers, the CoolMOS C7 600V devices offer a cost reduction in magnetics. Due to the significantly lower gate charge and output capacitance, the C7 can be operated at two-times higher switching frequencies with only a marginal penalty in efficiency. This enables the size of magnetic components to be minimised, lowering the overall BoM cost. For example, doubling the switching frequency from 65 kHz to 130 kHz may reduce magnetic component cost by as much as 30%.