Re: Isolated FET/IGBT Pulse Driver for HV Applications ...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Conner <steve@xxxxxxxxxxxx>

Hi Rajesh, all,

I expect the gate capacitance will be too much. You need some "Wee 
Tiny FETs" ;-) Go through the catalog of your supplier to find FETs 
with similar gate charge, Vds, Rds(on) and current rating.

I developed an isolated gate driver design that uses the VN10LP and 
STD12NF06 MOSFETs, and can switch a 600A IGBT brick in about 400ns. 
It's transformer coupled, so has trouble with duty cycles much 
different from 50%, but that isn't a problem in my DRSSTC 
application, so I didn't bother with the extra latching circuitry 
needed to handle any duty cycle. (I don't trust that circuitry to 
work properly around Tesla coils anyway.)

The most up-to-date info on my design is in the 4hv.org thread-
http://4hv.org/e107_plugins/forum/forum_viewtopic.php?4896

Steve Conner
http://www.scopeboy.com/


Tesla list <tesla@xxxxxxxxxx> wrote:
Original poster: Sparktron01@xxxxxxxxxxx

Hi Rajesh
------------------------------
>
> The zetex FETs are not available in my place. Can I replace those
> FETs with IRF540 or IRF9540 ? Those transistors are easily available
> in my place.
>
> Has anyone tried the same circuit using some other FETs ?
-------------------------------


In short, I don't know. Comparing the ZETEX vs IRF
parts, the IRF parts have 60 times (P channel) or ~100
times (N channel) higher total gate capacitance of
ZETEX parts; this usually equates to higher charge
(CV) to operate gates and thereby slower slew rates
(t ~ CV/I)