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SN75DPHY440SS: maximum input trace

Jaden Yue
Expert 4755 points
Part Number: SN75DPHY440SS

Hi Team,

Do we have advanced solution of SN75DPHY440SS? From the datasheet our SN75DPHY440SS support 12 inch input trace, but customer's FPC cable has 14 inch input trace. We are concerning if our retimer can compensate such long trace?

If not, can they add one more retimer in trace, as below to boost the signal conditioning capacity?

Looking forward to your reply.

Best Regards,

Jaden Yue

  • 0
    TI__Guru*** 149340 points

    Jaden

    Can we ask for the actual insertion loss of this 14in FPC cable?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    TI__Expert 4755 points

    Hi David,

    Routing detail: MB -> FPC or FFC -> DB -> FPC or FFC -> MIPI device, total 14.3 inch

    Either FPC or FFC may be used considering cost.

    FPC loss: 219mm@1GHz is around -3.2dB

    FFC loss:  219mm@1.25GHz us around -1.37dB

    1. Please help estimate if SN75DPHY440SS can cover customer design case

    2. If not, is two SN75DPHY440SS in series feasible? Do we have usage experience and do we have any concern on it?

    3. If above two are unsuggested, do we have better solution to fit the design?

    Best Regards,

    Jaden Yue

  • 0 in reply to Jaden Yue
    TI__Guru*** 149340 points

    Jaden

    What is the required data rate? 

    For 1.5Gbps, what is the insertion loss for the FPC and the FFC cable? 

    For 1Gbps, what is the insertion loss for the FPGA and the FCC cable? 

    You can cascade two DPHY440 if one can't provide enough compensation.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    TI__Expert 4755 points

    Hi Daivd,

    Our MIPI design block diagram as following, the simulation result of FPC (1.5inch) insertion loss is -1dB, and FPC 8.8inch almost -3dB,

    Two question as below.

     

    1. As following block diagram shown, is possible place re-timer on touch board? Or it’s necessary to place on MB?
    2. As you mention, we can cascade two DPHY440, do you have spec. of trace length or any design suggestion?

    Best Regards,

    Jaden Yue

  • 0 in reply to Jaden Yue
    TI__Guru*** 149340 points

    Jaden

    The DPHY440 RX equalizer can provide compensation up to 4dB at 1Gbps and 5dB at 1.5Gbps as shown below

    Assume the FPC 1in loss of -1dB and the 8.8in loss of -3dB is at 1.5Gbps, 2.5in loss is around 0.6dB and 0.5in loss is around 0.12dB, so total loss is 4.7dB at 1.5Gbps. So one DPHY440 placed on the main board is sufficient. You can also add another DPHY440 on the touch board for additional margin. 

    The trace length will depend on the DPHY440 RX compensation capability, you want to place DPHY440 to maximize its EQ compensation as much as possible.

    Thanks

    David