900V GaN FETs in a 300kHz 2kW LLC Converter for High Input Voltage Applications

900V GaN FETs are here. Their superior reliability allows them to handle 1000V transient voltage and 900V DC link with reduced lifetime. This paper is to demonstrate 900V 50m Ω GaN FETs in a 300 kHz, 2kW LLC converter bridging high voltage systems (500V to 900V), and low voltage systems (45V to 50V). As 900V GaN FETs can handle higher voltages, it becomes less necessary to design 3-level LLC converters with 600/650V devices. A 2-level half bridge using 900V 50m Ω GaN FETs enables high frequency LLC converters for a wide-range of high-input-voltages. And, the GaN FETs are compatible with classic gate drive circuits for Si MOSFETs. A prototype has been evaluated with input voltages ranging from 500V to 900V and output power up to 2kW.