Using simplest form of my prior post.

Over Voltage and reverse polarity:

2 x say N Channel MOSFET*
1 x NPN jellybean transistor
3 x R

Add another jellybean and a few more R's for snap-off overvoltage
protection.

Add some glue probably just for transients etc - but no more than with
existing part.
Power dissipation under say 40 Watts at 100A compared to ~=3D 80 Watts for
existing part at 40A.
As power rises with I^2 that's "much" better.

* You can use 2 x P Channel and PNP but the N Channel is probabl;y more
available and cheaper at very high currents.
N Channel has effect of floating load at V+ during overvoltage cutoff. As
+ve side of lload is usually at V+ this is not a problem electrically but
may or may not be acceptable due to safety or other reasons. eg secondary
loads that do not share the protection-ve line and have their own ground
returns will continue to operate. This could be a bonus or a disaster
deep-ending on application.

Whether this can be compact enough for you is unknown.



            Russell McMahon
--=20
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