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Discrete SiC diodes vs SiC diodes intrinsic to SiC NFETs?

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cupoftea

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Hi,
Just looked through many 900-1200V SiC NFET datasheets.

Eg SiC NFET G3R75MT12D (1200V)

They all feature an internal diode with trr of approx. 25ns or so. Also, the internal diode has vf of around 4V or so.
…Though when you look through 1200v SiC diode datasheets, they don’t even show a trr value, and for same conditions have vf of some 2v or so.
Is this a common fact?...that discrete SiC diodes have lower vf and lower trr than the internal SiC diodes inside SiC nfets?
I think if SiC NFETs are to be used in LLC converters, it would be worth paralleling them with a discrete sic diode? (no need to heatsink the added sic diode)

SiC diode GC02MPS12-220 (1200V)
 

A designed rectifier will take some care about distributing
forward current for high-current survivability, and maybe
even try to make reverse breakdown (to some current level)
well behaved.

A MOSFET has diodes but it's evident that some device
designers have not expected the parasitic diodes to conduct
significant current, the Vf of the diode is not of interest
(though these may indeed matter to a power supply designer
and BOM cost would like the diode to be useful enough to
dispense with an external backstop). There are "avalanche rated"
MOSFETs which survive repetitive breakdown (up to some Joules
per stroke) and there are ones which are not.

If you're "off the map" then it's time to do your own abuse
testing (but realize than an unspecified attribute stands to
wander, drift, be changed over time, and for production you
would be best off to have a part that specifies what you
care about.
 
Recent SiC from all vendors are suited for hard commutation with temporary current flow through body diode. Current in third quadrant is carried by the active transistor most of the time, respectively diode voltage drop doesn't contribute much to total conduction losses.
 
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