I am designing a system which is consdering using PCI as backplanebus, which has six slot and 3 inches between each. I Can't decide IfI can route a pci clock longer than 2ns(i.e. 12inches). The pci specsays the maxium clock skew between two pci devices is 2ns ,but notsays the maxium length of the clock signal.Any ideas. Thanks.

The clock length is usually irrelevant (which is why its notspecified). Use a clock generator and splitter to drive each PCIclock independently (the clock is *NOT* multi-drop) and equalize theirlengths on the backplane, as well as the plug-in card. Watch thetrace length on the cards (it's usually a constant).

Can I route a PCI Clock line longer than 2ns?

Jun 19, 2009 21 Replies

Rate this thread:

Martin Riddle 17 years ago

PCIe 2.0 is a differential signaling bus, with up to 32 'lanes'. The data does not have to arrive at the same time as it does in PCI (a parallel bus). As a result extenders are probably easier to make, can be longer, and still meet the specs. I havent found a free copy of PCIe 2.0, so I cant say for sure, but it does look to be the case. Some information says max bus length is 20 inches(PCIe 1.0) and 10m (PCIe 2.0).

Cheers

Vote

springzzz 17 years ago

rved

side

ion

=A0I think

timing

2ns

itched.

ies

what

That's true! PCIe use LVDS signal lines for transferring data. And the code scheme is 8b10b. Which can encapsule clock into the stream. But if you use more than one lane. Channel bonding must be cared.

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required