Re: [SI-LIST] : PCI bus impedance

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From: Scott McMorrow (scott@vasthorizons.com)
Date: Mon May 14 2001 - 10:50:03 PDT


Patel,

Do your simulations at 50 ohms -10%, with your add-in PCI cards
at the maximum Z0 in the specification. Use the fast driver corner
and perform you simulations. Then use the slow driver corner and
perform simulations. If you meet all signalling criteria for the PCI
bus, then 50 ohms works for you.

regards,

scott

--
Scott McMorrow
Principal Engineer
SiQual, Signal Quality Engineering
18735 SW Boones Ferry Road
Tualatin, OR  97062-3090
(503) 885-1231
http://www.siqual.com

"Patel, Bhavesh" wrote:

> Hi! Gurus, I was simulating a PCI bus with 50ohm trace impedance because we > generally try to keep on all our boards 50ohm single ended & 100ohm > differential(easy for the fab house). Now, the vendor says use 65ohm trace > impedance and I did simulations with 65ohm but I don't see much difference > i.e. not significant where I would say'YES' let's go to 65ohm. Also, if I > have to do 65ohm then it will eating up my routing layers because this bus > is confined to one section of my board. > I needed some feedback regarding this and whether it will really make or > break the PCI bus by going from 50ohm to 65ohm. > Thanks in advance > Bhavesh Patel > > **** To unsubscribe from si-list or si-list-digest: send e-mail to > majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP. > si-list archives are accessible at http://www.qsl.net/wb6tpu > ****

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