Hello Andy and Chris,
Have been following your discussion with interest. I too experienced the "hand
grenade effect" of removing the drive whilst using DC coupling. Dave YXM put me
right some years ago.
Thanks Andy for the further explanation.
I have always been perplexed by the distortion of the gate pulse that occurs
when the drain volts are applied.
This sometimes appears to show up as a slight instability on tail of the drain
pulse. Probably of no importance but never heard anyone mention it.
Would appreciate any comments
Mike -GW4HXO
___________________________________________________________________________
Subject: Re[2]: LF: Protecting a MOSFET driver chip from MOSFET failure?
Hello Andy,
Monday, August 10, 2015
> No, capacitive coupling with diode restorationends up with near-enough
> the same voltage applied to the gate as you had in thr first place.
> A 0/12v output from the driver chips ends up at -0.7 /+ 11.3 V
> (assuming 0.7V diode drop)
> As for the question of the dual drive with resistors. The resistors
> may as well say in, just to smooth off edges and reduce dissipation in
> the driver. i doubt you'll notice any difference.
> Andy G4JNT
OK, thanks and sorry for the naive questions, lots to learn, I was amused by my
friend calling power FET's "Fire Emitting Transistors". I see his point now,
they do go with a good bang and sizzle! The wife smelt them downstairs and
asked wearily if it meant a longer wait before a job she attached great
importance to, but I classed as a boring irrelevance, got done...
--
Best regards,
Chris mailto:[email protected]
|
