Hi Bob, thanks for the reply. The reason I am looking at IGBTs is for
their use in theatrical light dimming. They seem to have huge advantages
over triac/scr dimming, and I'd like to experiment with that. If what
you say is correct (and I have no reason to doubt that it is), why are a
number of manufacturers using IGBTs instead of bipolar transistors? My
electronic design skills are completely self taught, so I just "don't
get it" when it comes to certain design issues. Have you driven the
IGBTs with a PIC? I was looking at the Fuji Semiconductor site, and they
seem to have a nice driver hybrid IC that in theory would make
triggering them quite easy. Because I'm looking at dimming, my loads
wouldn't be more than 2400 Watts at 120 volts. I understand I'd have to
use two IGBTs back to back to dim both sides of the AC wave. Fuji has a
nice 600V 50A dual pack that seems like it would meet my specs (if only
just barely :)).

Anyway, what would you reccomend? If I went with IGBTs, can you
reccomend a manufacturer and perhaps some part numbers? If bipolar
transistor, same request. I hope you can clear up some of my confusion.

Thanks!

Josh Koffman
joshy@3mtmp.com


Bob Blick wrote:

> I've (ab)used quite a few IGBT's.
>
> Usually if you need to switch high voltage you use a bipolar transistor.
> Usually to drive high current you use a MOSFET. What if you need both?
> That's where an IGBT comes in handy.
>
> Rules of thumb regarding their use:
>
> Used for very high voltage and high current. Think of them as a bipolar
> transistor with a MOSFET driver. Unfortunately to drive them fast you must
> absolutely drive the gate negative.
>
> Do not consider them for use under 500 volts.
>
> Avoid them unless you need them.
>
> Cheerful regards,
>
> Bob Blick

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads