PNP/NPN fet drive for hi-side Buck converter fet at 200khz

Hello,
Can you confirm that PNP/NPN type FET drives are unsuitable for 200khz operation?
Its 40W out, and 100vin and 80vout.
The PNP/NPN is pulsing into a pulse transformer with a DC restore capacitor and diode on the secondary.

please upload schematic
don't forget the part No.

We are using the diodes.com BJT's due to their high hfe at high Ic. -But even though these are the best and fastest, (and are well known for this pnp/npn fet drive useage) we still don't think they are good for 200khz?...because no BJTs are suitable for that.?

Are you saying you are making a 40 watt FET driver?

Depends how you drive them we have pnp/npn totem poles running at 400kHz 2 amp peak out, if the drive is insufficient there will always be problems, there are mosfet based FET dirver chips that will do this easily at 200kHz at 4 amps out with a small heatsink glued on top.

thanks, this ltspice sim is our setup, (ot at least its representative) unfortunately we cannot use chips as the temperature (170c ambient) is too hot.

watch out for leakage currents at high temp (Icbo) these can be large enough to upset things, turn xtors on, etc.

What are the part numbers for the BJTs? After a bit of browsing I can't find any discrete ones from diodes rated for 170C. Of the few I can find from other manufacturers, none of them seem to spec performance at the upper end of the temperature range.

Too bad nobody seems to make small signal SiC PNP/NPN BJTs.

I've done some bipolar power MOSFET drivers (back in the
'80s and '90s, before HV CMOS / BCDMOS was suitably
robust for my end markets). Took a lot of care to stay out
of saturation and meet the ~50nS prop delays, loaded.
Those could run out past 1MHz but really the frequency
is less the problem, than the short-pulse limit - where do
you start to see runt pulses which could drive the FETs
badly enough to damage? What then is your min / max
duty cycle position, and does this leave margin in the
design's control range vs VIN, IOUT, etc.?

Now doing this with discretes, you'd care a lot about the
saturation behavior and this tends to be poorly spec'd
(if at all) - let alone modeled for you to play with bias
and clamping accurately enough to ensure the design
works, and works indefinitely.

Never seen a SiC PNP. Have seen "super junction
transistors" from GeneSiC which sure do look like an
NPN, although they purport to be majority-carrier-
only. Fast, tough (good avalanche rating, but you
do not care, here), come in not-huge (but not that
petite) currents on up to tens of amps. Some at
Digi-Key and other distributors.

My first bipolar MOSFET driver in fact used an all-NPN
totem pole, with PNPs playing only supporting roles -
a traditional TTL phase splitter, basically - and if you
can stand the waste heat in the pullup resistor the
sky's about the limit for implementing a discrete SJT
based gate-drive (or for that matter, power train).