Running a Synch Rect FET when off...so only its diode is used.

[cupoftea]

Hi,
We have got to run a messed up design of a 300W Synch Pushpull
(24vin 32vout 225khz )
Initially want to run it with the Synch FETs OFF, so we just use their internal diode.
What do you think the trr of the internal diode will be at 13A of current?
(The datasheet only gives it for 96A of current and its 250ns)

The FET is IPTG111N20NM3FD

https://www.infineon.com/dgdl/Infineon-IPTG111N20NM3FD-DataSheet-v02_00-EN.pdf?fileId=5546d46277921c320177aa5221467dea

Attached is the v and i across the diode from LTspice....i guess the "resetting magnetising current effect" is making it not have that much reverse votlage suddenly impressed across it when it turns off....aslo attached is the LTspice

 

[dick_freebird]

Is this 96A through a diode that's built for it (per DS or guidance) or is this a diode that just happens to be there?

Current balance through device segments and metal branches that are not expected / advertised capable may not have been a design concern and hot spotting might be a prob. I'd think about some over-the-top testing w/ sample size to check margin-in-mode.

 

[cupoftea]

Thanks, the intrinsic diode is said to be capable of 108A of continuous current, as such, i didnt think that this diode could be of inferior quality