UCC28780: UCC28780

Hello Robin,

The LMG5200 GaN half-bridge is rated for only 80V and so is unsuitable for use with a 380V input rail.

Selections from the LMG3410 and -3411 family of 600-V GaN switches would be more appropriate for ACF at power levels above 50W.
Silicon MOSFETs can work at all power levels, too. Both GaN and Si Fets can be used to achieve very high efficiency levels. The main difference is switching speed: the GaN MOSFETs have lower Coss so can be driven at higher frequencies which allows for higher power density using a smaller transformer.

Currently, GaN devices are advantageous for high-frequency conversion but are relatively more expensive than Si devices.
They are not yet as economical to use at lower power levels, despite their speed advantage.
But whether you choose GaN or Si MOSFETs, the overall efficiency is not contingent on the type of MOSFET, but on how well the entire power conversion stage is designed from input to output. Losses must be minimized in all of the power-path components, not just the switching FETs. Losses are easier to optimize under narrow-range operating conditions, than if a converter must operate over wide input and output ranges.

Regards,
Ulrich

Ulrich
thnx much.
Yeah, I am hard nosed about all losses. Plus, our rail is regulated at 380V from a nonisolated PFC( also resonant, hi eff topology).

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