[TCML] IGBT paralleling

dave pierson dave_p at comcast.net
Mon Jul 12 09:34:41 MDT 2010


I'mve no idea what a 'handling voltage' spec is.
In my training there is max voltage, or standoff voltage.
or withstand voltage spec.  This is the voltage the
device is specced to NOT breakdown under, when 'off',
(The actual voltage for any given specimen will be higher,
 a bit, but don't plan on it....).  This means that same
 spec is more or less the max the device will 'handle' in
 ESD as it is 'handled' during assembly, etc.

I can think of no reason why the applied voltage
'needs' to 'fill' this rating: the device should be
quite happy anywhere under the rating.  BUT: Higher
ratings cost more dollars (euro's, whatever...).  In that
sense of the full voltage rating is not being 'used'
then money is being wasted.  Or.  The resulting design
is more rugged/reliable.  Its a design tradeoff...

One thing I've not seen mentioned (did I miss it?):

Paralleling 'things', especially active devices, can be
 tricky.  Most notably, the devices may not QUITE match:
   'identical parts aren't': Frumps law of design...

Paralleling power devices can result in Not Equal 'sharing'
of currents.  Either forced sharing, or conscious
allowance is in order...
 best
New dwp:     dave_p at comcast.net



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