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DS110DF111: Minimum Trace Length?

Kurt Raichle
Prodigy 30 points
Part Number: DS110DF111


I was considering using the DS110DF111 retimer on a program to fix a signal integrity issue.  A colleague mentioned he had heard someone had an issue using one of these parts when the trace lengths weren’t long enough between the retimer and the device being retimed.

 

Can someone provide any details that may relate to this concern?  I check on the Forums and nothing seems to match.

 

Thanks

  • 0
    TI__Mastermind 43795 points

    Hi Kurt,

    There is no absolute minimum, for very short lengths we can program or adjust the retimer configuration to ensure robust Tx/Rx performance.

    As a general signal integrity rule (for the cleanest eye diagram) I would recommend to keep the retimer output at least 1 inch from any connector.

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Prodigy 30 points

    Hi Lee,

    In general there's about 5-7 inches between the retimer and device being retimed.  Although, the retimer will be on a small loopback board, which is pretty much a mating connector and the retimer.  The distance from the retimer and connector will be encroaching that 1 inch min I'm guessing. 

    Also, the plan is to pin strap the part for normal operation.  We'll lay it out so we can change the strapping options to allow I2C interrogation to pull an eye diagram and verify the design, but didn't plan on having I2C control normally.

    If you have any pointers or mitigation suggestions you can share, please let me know.

    Thanks for responding,

    Kurt

  • 0 in reply to Kurt Raichle
    TI__Mastermind 43795 points

    Hi Kurt,

    This distance sounds fine.  I do not expect any issues at the 5-7 inch distance.  With the connector at ~ 1" from the retimer output I would recommend to optimize the connector footprint to maintain the transmission line target impedance as much as possible.

    For many small connectors this just involves a small amount of GND relief under the high speed connector pins.

    Regards,

    Lee