[TCML] Silicon Carbide MOSFET for SSTC designs

[Jim Lux]

On 6/16/11 12:10 PM, Steve Ward wrote:
> While these new SiC devices are very fast switching, they still have rather
> poor conduction losses compared to even "cheap" MOSFETs and IGBTs.  Unless
> you are trying some exotic, very high frequency SSTC (in the MHz range),
> then i see no reason to use these SiC fets.  They will probably perform
> worse than a 5 dollar MOSFET or IGBT that switches 2-3 times slower but has
> 2-3X less conduction loss.
>
> I also dont see how this sort of thing could ever replace the IGBT, at least
> for folks like me who exploit the IGBTs ability to handle tremendous peak
> currents.  These SiC things look like they have a fixed on resistance, which
> means their losses go up with the square of the current.  IGBTs maintain
> relatively low voltage drop even with pulses 10X their average current
> rating, and as far as i can see, SiC inherently cant do this.
>
> $46 for one of those sounds pretty absurd, i bet they dont get used much
> yet.
>


SiC is extremely useful if you have a high temperature or difficult to 
cool application. I haven't looked at the data sheet, but I'll be the Tj 
maximum is pretty high.