>> ..., sometimes the whole IC literally blows up.

Sounds like the chip got into latch-up mode.

This is caused by too much current on a pin (in this case ESD-spike),
making part of the chip trigger like an SCR. 

It is probable that the chip in some cases should have survived the
ESD-spike itself, if we just eliminated the high current.

This might be done by putting a series resistor to the supply (The supply
current is very low) and a zener and a small cap (10nF) on the chip side to
stabilize and limit.

If latchup occours it might reset itself if R is hight enough, else it
resets at power off.

Of course, use all ESD protection discussed here too

/Morgan
        Morgan Olsson                   ph  +46(0)414 70741
        MORGANS REGLERTEKNIK            fax +46(0)414 70331
        H�LLEK�S           (in A-Z letters: "HALLEKAS")
        SE-277 35 KIVIK, SWEDEN               mrt@iname.com
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