GaN Power IC – 150W AC-DC PFC + LLC Demo BoardDecember 10, 2019 by Paul Shepard
The NVE031E gallium-nitride demonstration board from Navitas Semiconductor uses the company's GaNFast™ power ICs a Critical Conduction Mode (CrCM/DCM) PFC and ac-dc power stage (ac to 400Vdc), followed by an LLC dc-dc converter (400- to 19-Vdc). For both stages, the switching frequency was increased to the maximum allowed by the off-the-shelf control ICs available.
The board is designed to be a ‘demonstration' board, and is not yet optimized as a production design. With this design, a power density of 2.18W/cc or 35.75W/in3 is achieved, which is around 2x typical and 40% more than the best-on-class Si-based design today. Customer designs achieve even higher power density.
The PFC section is a standard ON Semi NCP1615 CrCM/DCM powering 2x NV6115 (parallel) GaNFast Power ICs directly. Critical mode PFC (also known as boundary mode) is a soft-switching topology which allows higher frequency operation.
The dc-dc section uses the NCP13992 current-mode resonant controller (LLC) driving NV6115s. The NV6115s have monolithically-integrated gate drivers, so the NCP13992's drivers are not used and loss is minimized.
For secondary-side synchronous rectification, two NCP43080 controllers are used to drive silicon 60V FETs.
This demo board is constructed using 1 main board (4-layer) plus 3 daughtercards (4-layer) (see image below). This assists evaluation and allows the user to exchange daughtercards for experimentation, plus allows for easy heat sinking and thermal management. PCB material is standard FR4 with 2 oz copper.