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TUSB1064: About AC Coupling Capacitor

Hide
Guru 21045 points
Part Number: TUSB1064

Hi Team,

 

I have two questions.

 

[Q1]

We understand that the recommended range of total series capacitance is from 75nF to 265nF.

However, the total series capacitance of red frame line is 50nF so it is out of a recommended range.

Is there any problem?

 

[Q2]

Can I add "330nF" to the green frame line according to “ECN Rx AC Coupling Capacitor Option”?


 

Regards,

Kanemaru

  • 0
    TI__Guru**** 157496 points
    Kanemaru

    TUSB1064 is a redriver, so the capitance as shown in red is separated from each other. You will have 100nF on one side and 100nF on the other side. In fact, for TX between Type C receptacle and TUSB1064, the new recommended capacitance is 220nF. But the capacitance between TUSB1064 and USB3.1 hub is still 100nF.

    You can use 330nF on the Green Frame Line, with 330nF on the RX and 100nF on the corresponding TX, you will have 76nF total capacitance. If corresponding TX is 220nF, then you will have 132nF total capacitance.

    Thanks
    David
  • 0 in reply to David (ASIC) Liu
    Guru 21045 points

    Hi David-san,

     

    Thank you for your prompt reply.

    I have one more question.

     

    Red frame line is separated from each other (so Tx and Rx AC coupling capacitor isn’t series capacitance.).

    But Green frame line is not separated (so Tx and Rx AC cupling capacitor is series capacitance).

    What is the difference?

     

    Regards,

    Kanemaru

  • 0 in reply to Hide
    TI__Guru**** 157496 points

    Hideto-san

    Green frame and red frame are the same, TX and RX are separated from each other since TUSB1064 is a redriver. 

    For the red frame, the reason there is no series capacitance is because the series capacitance is on the host TX side. 

    You can put serial capacitance on the RX side, but this is optional. If you do put series capacitance on the RX side, the recommended value is 330nF.

    Thanks

    David