3.3V Device driving a 5V Bus

[Andrew Stone <andrews@met.crc.org.au>]

Dear Experts

I am currently designing a universal card which uses an ALTERA 10k part,
containing the PCI interface. The part in question is capable of driving
a 3.3V bus to spec. but I need this to be a universal card so that it
can be plugged into any PC. The 10k part has 5.3V tollerant inputs which
clearly won't survive indefinitely on a 5V PCI bus which has significant
overshoot. 

As I understand it I could clamp to the Vio & Ground pins via schottky
diodes or perhaps clamp to ground using Zener diodes which have a knee
at say 5V1. 

I found one mention in the archives of a Texas Instruments Schottky
Diode array being used on a proprietry backplane but these arrays are
physically quite large to be used on a plugin card (standard 1.27mm lead
pitch SO20 pack, 3 parts required). I don't know of anyone manufacturing
zener arrays.

Does anyone have any suggestions or experience with this sort of
problem.

If you prefer to e-mail me direct please send to:

andrewstone@ozemail.com.au

Many thanks

Andrew Stone