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RE: "Current limited" IGBTs

Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> 

Hi all,

The powerex CMXXXXX-XX-F (F series) are the current limited ones. They are
"Trench gate" IGBTs, and have such a high short circuit current that they
need to be limited by a little circuit which senses current and clamps the
gate drive voltage, if they are to be "short circuit proof" for industrial
applications (motor drives etc)

The current limit board is potted inside the IGBT and AFAIK can't be
disabled, unless you get REAL lucky with a power drill :-o But I wouldn't
worry about it, as the current limit is quite generous, something like 4-6x
the rated current, and Jimmy and Steve have shown that you can get
stupendous sparks with really quite modest primary currents.

My own theory and simulation work certainly supports this conclusion, in
fact I almost believe the "5ft from TO-247s" thing myself ::) I have a SGTC
that does 40" sparks, and Antonio showed that the exact same coil could be
driven as an ISSTC with comparable bang energy, and primary currents of only
~100A, which is a walk in the park for TO-247 IGBTs.

For extra GeekPoints: The current limit board in F-series IGBTs senses
current through a tiny second emitter on one of the IGBT chips, which picks
up maybe 0.1% of the total current.

Steve C.