GaN Devices in Resonant LLC Converters: System-level considerations

Resonant or soft-switching converters are common in the high-voltage (400?600 V) space to reduce form factor while maintaining high efficiency. These supplies target topologies such as the LLC, phase-shifted full bridge, and two-switch forward with power levels between 400 W and 5 kW. The LLC converter is a popular topology in this space as it can achieve zero-voltage switching (ZVS) over a wide load range [1]. This article is focused on LLC converters with a 350?400-V input range and an isolated 12 or 48 VDC output. Applications include the second stage of traditional ac/dc supplies for server and telecom markets, electric vehicle (EV) bus converters, and board-mounted supplies for the high-voltage dc distribution trend in rack-mount environments.