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Looking at the top distributors, seems only N-channel power SiC are carried. Why is that?

rdtsc
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3 Answers3

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Not just SiC. All high-voltage MOSFETs.

There's no point due to how they are or would be used.

SiC is for high voltage and the max gate-source voltage is the limiting factor when using a PMOS high-side switch to simplify gate drive. 30V is pushing it, let alone 600V. So for high-side, high-voltage switches you need gate circuitry anyways no matter what you use. If you need it anyways, might as well go with a more efficient, cheaper N-channel regardless of whether it is SiC or not.

DKNguyen
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Check this out: https://ieeexplore.ieee.org/document/8022990 A 730 V P-Channel Vertical SiC Power MOSFET, good idea for the top half of a high voltage bridge.....

Tom Murray
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I believe the process of producing them is more complicated but I am not sure. They do have a higher on-resistance than N-channel MOSFETs this is disadvantageous due to higher power losses. So therefore most people prefer N-channel MOSFETS. Also, they are enabled when applying a negative voltage to the gate compared to the source (Vgs), N-channels can simply be operated with a positive Vgs.

For high side switching applications the P-channel are sometimes easier to use because the gate voltage does not have to exceed your available power supply voltage which is the case with a N-channel MOSFET. However, in these cases often a bootstrap circuit can be used in combination with an N-channel MOSFET.

So in general there are not many cases in which a P-channel MOSFET is desired over N-channel.

WillyBogard
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  • The question was about silicon carbide MOSFETs specifically (of which there are no P ch devices as far as I know). – Andy aka Jul 08 '21 at 13:50
  • @Andyaka I think the answerer knows that. They just didn't retype SiC into their question. The situation in question is also broader then OP realizes which this answer implies. – DKNguyen Jul 08 '21 at 13:54
  • @Andyaka, I have seen it. But don't you think it could be the same for SiC as is the case for Si? This combined with the fact that SiC are less used than Si. You will probably get a very specific case that someone really requires a P-channel SiC. – WillyBogard Jul 08 '21 at 14:03
  • @WillyBogard you are answering as if P channel SiC MOSFETs exist hence, when you say that the process is more complicated and that they have a higher on resistance, you must have insight into something that all the main manufacturers and distributors don't. If you can find a p channel silicon carbide MOSFET that would be good to hear. – Andy aka Jul 08 '21 at 14:13
  • @Andyaka As you have said, they don't exist, but it is interesting to find that Fuji actually has a patent for P-Channel SiC MOSFET. https://patents.google.com/patent/US20100224886A1 – Bja Jul 09 '21 at 07:42