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DS100KR401: Is there a maximum length that the repeater can support?

Tom Shyp
Prodigy 90 points

Other Parts Discussed in Thread: DS100KR401

Hello,

Regarding DS100KR401:  Is there a maximum length that the repeater can support? 

For example, channel lengths may be set something like this: Processor<-25inches->repeater<-25inches->switch processor.  Will this be an issue?

 

Thank you.

  • 0
    TI__Mastermind 29655 points

    Hi Tom,

    In general, the repeaters can support much greater input trace length than output trace length.

    The maximum length that the repeater can support depends on the trace material used, the speed of the signal, and how the trace is routed through the board. For instance, with the DS100KR401 operating at 8Gbps, the DS100KR401 has been able to resolve signal up to 40in of FR-4, 4mil stripline on the input (no additional trace on the output). However, the DS100KR401 at the same speed can only drive a resolvable signal up to 20in of FR-4, 4mil stripline (no additional trace on the input). In short, "maximum length" is determined on a case-by-case basis.

    The repeater in the configuration you mentioned above would only be a concern to me regarding the driver output. While the repeater should have no trouble resolving the 25in on the receiver input, it may be more challenging to drive an output of 25in if both the processor and switch processor do not have equalizers before they begin processing the data.

    Some questions:

    1. What kind of trace length are you using (i.e. microstrip v. stripline)?

    2. Is there some signal conditioning occurring at the receive end of the processors?

    3. Is the transmission data bidirectional? If it is unidirectional, I would place the repeater farther from the source device and closer to the target device to maximize signal conditioning performance, if possible.

    Regards,

    Michael