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SN75DPHY440SS: Technical Inquiry

TI-CSC
Genius 12945 points
Part Number: SN75DPHY440SS

Hello E2E Experts,

Good day.

Can we use this part between 30cm and 50cm? May this work if we put It on the Rx side (after the 30-50cm)? Or it would be mandatory to out it at the beginning of the TX signal? I ask this just for a question of cost.

 On the other hand, the device has an I2C interface to set up the equalization. Is there any default setup? For the distances indicated, do you believe the chip could work with the default configuration?

Thank you in advance for your support.

Kind Regards,

Jonard Rico
Texas Instruments Customer Support

  • 0
    TI__Guru**** 176811 points

    Jonard

    It depends on the loss of the 30cm and 50cm. The DPHY440 supports up to 4dB EQ on its Rx and 2.5dB DE on its TX. These features were intended to some extent to compensate the ISI loss in the channel. In the DPHY440 datasheet, we demonstrate that DPHY440 can support 12in trace as an example.

    As to place DPHY440 closer to the Rx or Tx it is really a system choice. If one would like to take use of DPHY440’s EQ capability for ISI compensation he may want DPHY440 close to TX. Please be noted as a repeater, DPHY400 is intended to eliminate the timing skew due to channel differences. As long as the input timing within DPHY440’s spec requirement, it is able to re-align clock and data to improve the system’s timing margin. So if one wants the “de-skew” feature of DPHY440, the repeater should be placed in a location where skew has happened.

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    TI__Genius 12945 points

    Hello David,

    I understand that it’s not an easy question to be answered without any doubt. If we need to make some tests comparing the use of one device on the RX side or in the TX side, what do you use to test it? Any Eval board? What one could be available with software as a tool to help the testing?

    Thank you in advance for your support.

    Regards,

    CSC

  • 0 in reply to TI-CSC
    TI__Guru**** 176811 points

    Hi, Jonard

    Correct, eval board will give them a good approximation through direct measurement. There is a DPHY440 eval board available on ti.com, https://www.ti.com/tool/DPHY440SSRHREVM.

    If they can measure the loss of the 30cm and 50cm at the Nyquist frequency of the targeted data rate, this will also give them an idea where the DPHY440 needs to be placed.

    Thanks

    David