Re: 3.3V PCI

[Neal Palmer <neal@dinigroup.com>]

If you are making a universal PCI card, then you will have problems with
legacy motherboards because most consumer motherboards over 2 years old
were made without 3.3V supplied to slots.  You will have to derive 3.3V
from 5V.

If you are making a 3.3V only PCI card, then you should use the provided
3.3V.

As to motherboards only having 2 3.3V slots: 3.3V is required for 66Mhz so
motherboards that have 66Mhz slots must have some 3.3V slots.  But there
are thousands of 5V only PCI cards, and motherboard suppliers realize this
and must make 5V slots on their motherboards.  You can find some servers
made by Intel or Dell that have more than 2 66Mhz slots (on different PCI
busses).

On Fri, 12 Jan 2001, Paul Capes wrote:

> Hi all,
> 
> We are developing new 64 bit/66 MHz PCI boards on which most of the
> components rely on 3.3/2.5V supplies. Due to the speed and density of
> these products, I am very reluctant to derive these supplies from the 5V
> rail. However, I cannot find any motherboards with more than two 3.3V
> PCI slots. Would anybody care to comment on the approach they are taking
> with their current product development (requiring 3.3V supplied by the
> host).
> 
> --
> Paul Capes
> 
> Engineering
> Interactive Circuits and Systems Ltd.
> 5430 Canotek Road
> Gloucester, Ontario
> Canada K1J 9G2
> Tel (613) 749-9241
> Fax (613) 749-9461
> Email pcapes@ics-ltd.com
> 
> 

-- Neal Palmer

The Dini Group
1010 Pearl St #6
La Jolla, CA 92037
(858) 454-3419 x16
(858) 454-1728 (Fax)