I don't think anyone has published the rate at which hFE decays, with respect to current magnitude and rate (is it a linear charge dose, square law, or..?), and how that translates to normal parameters.
If you'd like to take the effort to do it, I'm sure a few people would be appreciative, but I'm guessing you don't have that kind of time in the project...
Otherwise, might you be able to find a "self biased" transistor, that's fast enough, and which for some bizarre reason, just happens to have a reverse diode integrated already? (Worthy of note: mere 2N3904s will get transitions under 30ns, but you might not be able to afford the quiescent current to get there.)
You could also hack a SOD-323 (maybe) or MLF or 1206 diode in, as well. Crappy, but can probably still be managed via pick-n-place.
Tim
Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website:
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Folks,
I'd like to use a MMBT2369 in a design where there are no protection diodes. Mainly because the not so well performing FET that was in there had one integrated. So, in order to get very low storage time I'd like to use the gold-doped 2369 but of course there can be the occasional ESD event. There are 1k to 10k resistors up front, limiting the current. How low can the hfe go upon repeated zenering on the B-E junction?
I could live with a hfe as low as 5. But not if it eventually drops to 1 or zero.
It's a glorified level translator and I'd like to push transitions to less than 100nsec.