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Original question:

TUSB217-Q1: D1M, D2M and D1P, D2P pins connection method

TUSB217-Q1: TUSB217-Q1: D1M, D2M and D1P, D2P pins connection method

zehao chen
Intellectual 300 points
Part Number: TUSB217-Q1
Other Parts Discussed in Thread: TUSB217

Can anyone answer this question? Please, thanks!

  • 0
    Intellectual 300 points

    Hi,
    For some reasons, we design the circuit of tusb217-q1 as shown in the figure below, that is, the 9th and 10th pins of tusb217-q1 are not connected, and the 5th and 6th pins are respectively connected to DP and DM signal lines.
    The reason why we do it this way,Because I confirmed that D1M-D2M and D1P-D2P are physically connected through metal wires inside the tusb217-q1.And in this connection method,We have tested the eye diagram which is also OK.
    Can tusb217-q1 be used in this way? And I know that there may be some slight differences between the usage method recommended in the datasheet,but is there a greater risk?
    Because our product has been designed, if we modify it now, there will be a lot of certification needs to be repeated, which is more troublesome.So please make a detailed evaluation.
    thanks!

    When there is tusb217, from the eye diagram results, the compensation has worked.
    Here are Near End Eye Measurement Set up With Pre-channel Cable.BOOST Level = 2,RX_SEN Level = high.

    Pre-channel Cable = 1m:


    Pre-channel Cable = 4m:

    We did not test the eye diagram without tusb217.

    thanks!

  • 0 in reply to zehao chen
    TI__Guru 64326 points

    Hi,

    Based on your test result I do not foresee great risk in this design. In the layout you should make sure to minimize the stub from (Pin 5 & 6 to DP & DM) created by having TUSB217 in the configuration above (i.e. Keep TUSB217 as close as possible to DP and DM trace). As you mentioned this is not a recommended implementation but is workable for this device. 

  • 0 in reply to Malik Barton57
    Intellectual 300 points

    Hi,

    Thank you for your reply!I have kept the shortest stub.
    Thanks!