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Original question:

DS125DF1610: Circuit connection confirmation

DS125DF1610: Circuit connection confirmation

Lu Jialin
Prodigy 90 points
Part Number: DS125DF1610


Tool/software:

Hi TI Team

We have a new design requirement to confirm with you. Our customer would like to use the RX port to monitor a 2.7 Gbps PRBS signal in order to verify whether the PRBS is active. The updated circuit is shown below.

Since the corresponding TX port (e.g., TX_0B) of the monitoring RX pin (e.g., RX_0B) is floating, we would like to confirm with you whether this design is feasible. Please kindly help review and let us know if there are any concerns or recommendations.

Thanks

JL

  • 0
    TI__Genius 16261 points

    Hi JL, 

    This design is feasible and TX pins can be left floating in this case. 

    Best,
    J

  • 0 in reply to J
    Prodigy 90 points

    Hi J

    Thanks for your confirming

    Regarding the SMBus address configuration, we plan to use the following setup.
    Could you please advise if there are any recommended resistor value changes for ADDR0 and ADDR1?

    Current our schematic

    Thanks

    JL

  • 0 in reply to Lu Jialin
    TI__Genius 16261 points

    Hi JL, 

    If you are planning to set 7-bit address to 7'h18, 1k resistor to GND is recommended. 
    If you are planning to set the address to 7'h19, ADDR0 needs 20k resistor to GND. 

    Best,
    J

  • 0 in reply to J
    Prodigy 90 points

    HI J,

    Thank you for your confirmation. We have two new questions to clarify with you:

    1. In the Design Requirements, we noticed the guideline: “Place AC-coupling capacitors for the transmitter links near the receiver for that channel.”
      In our current circuit, the PRBS TX output is connected to the TMUXHS4212IRKST Multiplexer Switch ICs. We would like to confirm whether it is acceptable to place the AC-coupling capacitors near the TMUXHS4212IRKST instead.

    2.We plan to use the PRBS RX port to transmit a signal by itself to verify whether the PRBS is functioning properly. As shown by the green arrow path in the diagram below, AC-coupling capacitors will be added on the RX path to block low-frequency components. The signal will then be routed through the TMUXHS4212IRKST multiplexer switch IC to connect to the PRBS TX port. Could you please help review this circuit design and let us know if you have any suggestions or recommendations?

    Thanks

    JL

  • 0 in reply to Lu Jialin
    TI__Genius 16261 points

    Hi JL, 

    My understanding is that the retimer's PRBS generator will only transmit from the TX channel so your green arrow will have to go into other direction. 
    In this case, the AC capacitors will have to be close to the RX8, not A1X. 

    Best,
    J