At 13:39 01/11/99 -0600, John Payson wrote:
>I'd like to second the idea of protecting the power supply; if you
>zap a chip with a spike that's too much for the protection diodes,
>you'll destroy that pin's functionality but the rest of the chip
>should survive.  Most likely the spike is either causing the chip
>to see excessive voltage between VDD-Vss, or else it's causing the
>chip to latch up.  The former case should be preventable for the
>cost of one zener diode per chip (perhaps mounted on the reverse
>side of the board, tied directly to the legs); the latter case may
>be rendered non-fatal by current-limitting the supply.

wouldn't that be an application to use a TVS instead of a zener? isn't that
the type of app the TVSes are made  for (conducting energy spikes)? (i know
that a TVS is basically a zener, but it is one designed to absorb higher
energy spikes than a common zener.)

ge