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DS320PR1601: Do I use Redrivers/Retimers in Independent REFCLK topologies?

Antonio Farthing
Prodigy 20 points
Part Number: DS320PR1601
Other Parts Discussed in Thread: DS160PT801

I need help determining if Redrivers or Retimers are most appropriate for my PCIe architecture.

I'm implementing PCIe over VPX Backplane and will have a star-fabric topology from (1) slot to (8) downstream slots.
I have concluded that I will need to employ an Independent Reference Clock topology... meaning REFCLK will not be distributed over backplane to each downstream slot.

Each downstream slot will be required to provide a local REFCLK for its PCIe port.

Given the above, is there any critical factors I need to consider before moving forward with using Redrivers over Retimers?

  • 0
    TI__Genius 11750 points

    Hi Antonio,

    I've paged a team member, we'll aim to have a detailed response for you by tomorrow.

    Best,

    Evan Su

  • 0 in reply to Evan Su
    TI__Expert 3590 points

    Hi Antonio,


    Please consider that using a redriver will be easier in terms of your REFCLK consideration because redrivers do not need clocking to operate. When it comes to using a retimer there will be more clock routing to consider. if a redriver is used, there is no need for clock routing on the path between the root complex and the endpoint, but if the backplane uses a retimer, typically the root complex clock would need to be routed to it, which could go against your motivation for using separate reference clocks.

    The Gen 4 retimer DS160PT801 supports using a separate REFCLK for different PCIe ports (endpoints) when the root complex and retimer share the same clock. Please consider the other differences of using a retimer or a redriver by watching this TIPL video: https://www.ti.com/video/6314066968112?keyMatch=RETIMER%20VS%20REDRIVER


    Best regards,
    Nick Peabody