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PCI-X Backplane Specification

Discussion in 'Electronic Design' started by yy7d6, Nov 28, 2006.

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  1. yy7d6

    yy7d6 Guest

    Hi can someone direct me to the PCI-X 66Mhz Backplane Specification, or
    the like?
  2. PeteS

    PeteS Guest

    As far as I know, there is no such thing. I have the PCI-X spec (1.0a)
    in front of me, and it refers only to PCB implementations. The maximum
    length for PCI-X 133 is 8 inches - I'll have to look for the 66MHz spec.


  3. yy7d6

    yy7d6 Guest

    8-inches, then 66Mhz should have longer maximum trace length.
    Is that the "PCI-X Addendum to the PCI Local Bus" Specification you are
    BTW, are you familiar with Single board computers(SBC) with one
    PCI/PCI-x edge connector (i.e for the connection of SBC to Backplane);
    the length of the overall trace of the PCI is SBC board pci
    traces+backplane traces right?,
    What bothers me is that i know the routing guidelines for Add-In card
    but does that also apply for PCI on motherboard or SBCs?

    What revision of the specification do you have? In my copy it says for
    the PCI 32-bit signals 1.5", for the 64-bit extenstion 2.5"; can you
    site the information about the 8" (because i'm really having problems
    keeping up with the length limit).

    Ayon kay PeteS:
  4. PeteS

    PeteS Guest

    The PCI spec can be very confusing.

    Lengths are specified two ways:

    Motherboard is specified in terms of propagation delay
    Add-in cards are specified in terms of length on FR4

    The add-in card lengths are the minimums for the entire system,

    Be careful of the signals on 64 bit - the original 32 bit signals still
    require the standard lengths. In addition, make sure that REQ64 has a
    *longer* prop delay than reset to make sure it is valid during the
    rising edge of reset. If you give them the same prop delays, you can
    always use a higher value pullup to 'slow' the rising edge, but make
    sure you avoid the potential race condition.


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