[EMAIL PROTECTED] wrote:
Here's a picture of what I'm trying to accomplish :
http://www.geocities.com/fazool1_2000/geda/sample.pdf
Switching frequency is around 500KHz - edges may be fast, but I'm not
yet sure how fast. I've been simulating with 1ns rise/fall time, but
that number isn't based on any hard data.
In simulation, this arrangement works - but I am now certain the lid
will blow off the mosfet :-) Next step is to try to use the voltage
divider at the gate.
Dan, are you saying that the Cgd will allow the fast transient input to
couple to the output? Interesting - I didn't think about that. That
sort of thing should show up in simulation, I expect. There's some
small signal mosfet's from ON semi - just ran across them this morning.
The Vgs max is +/-6V, and the gate has built-in transient supression (
http://www.onsemi.com/pub/Collateral/NTA4153N-D.PDF ). Maybe good? I
need to look closer.
yes, Cgd can allow a fast transient to couple to the output. It is more
of a concern if you have a much larger input than output (like you do)
and a following circuit which is not tolerant of that.
Ok, dumb question to follow here.... Why even bother with the level
converter? Is there a way to size your filter components to allow you
to drive 50 V directly? Obviously you have to watch out for
transients. If nothing else your particular circuit looks like a
voltage divider would work quite well, just replace R1 with a series R
to the 50V and a shunt R to ground. Size them to give 4.12k looking
back into it and to give the required attenuation.
-Dan
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