5V vs. 3.3V

["Andrew Krenz" <a.krenz@aristoslogic.com>]

Hi,

We're designing a product with a PCI bus interface and the question of
5V tolerance has come up.  It seems that with shrinking process
geometries, 5V tolerant input buffers are becoming a thing of the past
(example: Xilinx Virtex-E FPGAs).  The question of whether our own
product should be designed to be 5V tolerant has come up.  Though it
seems most PCI ASICs sold these days don't use 5V for power anymore,
nearly all PC motherboards have 5V-keyed PCI slots.  To me this means
whatever's connected to that bus better have 5V tolerant I/O buffers,
just in case an older 5V board is plugged in also.  I'm trying to get an
idea of how much left is out there still uses 5V, and just how important
it is to have 5V tolerance on a new PCI design.  Any input would be
appreciated!

Regards,
Andrew Krenz
Aristos Logic Corp.