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Original question:

DS125BR820: DS125BR820 application issue.

DS125BR820: DS125BR820 application issue.

Hugo Liu
Genius 5095 points

Part Number: DS125BR820

Hi Sir,

Our customer used as below Block diagram on Product, But have data lost issue.

if we have two board need to transmission on Big PCB size server, than use Repeater & ReTimeris. this okay?

Or Do you have any suggest for Long distance application?

  • 0
    TI__Mastermind 43795 points

    Hi Hugo,

    There is nothing wrong with the block diagram in concept.  The DS125BR820 should work well between a PCIe Switch and Retimer.  Can you be more specific about the data loss issue?

    The only issue I can think of with two retimers and the repeater in the link could be receiver detect system timing.  Since the repeaters should always have active PCIe components on both sides you could try to set RXDET pin to the "1" logic level.  That is pull RXDET high to 3.3V if VIN = 3.3V or pull high to VDD if VIN = Float.

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Genius 5095 points

    Hi Sir,

    The fail symptom is PCIe link speed unstable when system doing power cycle(reboot) test.

    Sometime link speed drop to Gen2/Gen1 and sometime is Gen3.

    And below picture is IDT’s document about the retimer and repeater cascade application, FYR.

  • 0 in reply to Hugo Liu
    TI__Mastermind 43795 points

    Hi Hugo,

    The DS125BR820 has passed PCI-SIG plugfest testing.  It can re-transmit all of the PCIe Tx presets correctly.  Can you give me additional information about the channel topology and attenuation of the link between the PCIe Switch <-> BR820 <-> Retimer?  It could be the settings which are not optimal for the connected interface.

    Regards,

    Lee