Within the TDK-Lambda-branded PFH500F‑28, a pair of GaN transistors have been used in a ‘bridge-less’ front-end power factor correction stage, raising efficiency in the PFC stage to 98% and peak efficiency of the over-all supply to 92% peak.

According to marketing director Martin Southam, this is the first time the firm has used GaN components in an ac-dc PSU. He also said that the PFC stage could have been 0.5-1% more efficient – to 99% – at the expense of two more regular mosfets, and their drivers, to make a full bridge, but cost-benefit analysis and limited board space showed this was not the optimum solution for the intended markets.