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RE: Control line pull-ups on mixed 3v/5v system

Hi Wayne,
QuickLogic's QL5xxx family of configurable PCI bridges are designed to
connect the PCI connectors designated power rail supply's directly to the
device's Vccio, and without any external circuitry, make the design
universal PCI compliant according to PCI SIG 2.2.
This allows for a universal keyed PCI adapter card that can be plugged into
either a 3.3V or a 5.0V PCI slot. 
For further details, please check
<http://www.quicklogic.com/home.asp?PageID=291&sMenuID=174> &sMenuID=174
Thomas Oelsner

-----Original Message-----
From: Joseph Brcich [mailto:jbrcich@juniper.net]
Sent: Monday, July 22, 2002 9:21 PM
To: Wayne Eckertson; pci-sig@znyx.com
Subject: RE: Control line pull-ups on mixed 3v/5v system

The pull up-values specified are different for 3.3volt and 5 volt signaling.
We used PI5C3257 to switch between 1K and 2.7K. We also used a VIO detect
circuit to do the switch automatically.

-----Original Message-----
From: Wayne Eckertson [mailto:WayneEckertson@VersaLogic.com]
Sent: Monday, July 22, 2002 12:25 PM
To: 'pci-sig@znyx.com'
Subject: Control line pull-ups on mixed 3v/5v system

I am designing a system which will support either 3V or 5V PCI adapter cards
(not at the same time).  On-board devices are 3.3V, 5V tolerant.  Which rail
should the control lines be pulled to?  More simply, will a 3V only device
have problems if the control lines are pulled to the 5V rail and vise-versa?

Wayne Eckertson 
R+D Engineer 
VersaLogic Corp