• State Resolved
  • Locked Locked
  • Replies 8 replies
  • Subscribers 34 subscribers
  • Views 743 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DP83867CR: 1000BaseT compliance test

kenshow
Genius 3725 points

Part Number: DP83867CR
Other Parts Discussed in Thread: DP83869

Hi,

Could you advise me about compliance test.

When 1000BaseT compliance test is performed using TEST MODE, two item (OUTPUT VOLTAGE) ware fail as follows:
1000 Base-T, Point A Peak Output Voltage(w/ Disturbing Signal)
1000 Base-T, Point B Peak Output Voltage(w/ Disturbing Signal)
They are not enough peak voltages. The point A of actual value of point was 584.1mV and B was 588.4mV. Values of 670mV to 820mV are required to pass the voltage.

There are no particular problems with PHY circuits, power supplies, and settings. I am referring to snla239a.pdf.
Please let me know if there is a way to adjust the peak voltage amplitude.

Regards,
Kenshow

  • 0
    TI__Mastermind 18425 points

    Hi Kenshow,

    Is the RBIAS resistor 11kohm with 1% tolerance? Please also check the layout, the MDI traces should be 100ohms differential. Ideally PHY, magnetics, and RJ45 connector should be on the same board. The total distance between Phy and RJ-45 should be 2-3 inches. 

    -Regards

    Aniruddha

  • 0 in reply to Aniruddha Khadye
    Genius 3725 points

    Hi Aniruddha,

    We checked our design according to your advice and confirmed that there is no problem.
    I changed RBIAS to 10Kohm and confirmed it in the trial, but there was no change in particular.

    Do you have any other good ideas to pass the compliance test?
    Is there a way to work around this with register settings?

    Regards,
    Kenshow

  • 0 in reply to kenshow
    Genius 3725 points

    Hi Aniruddha,

    I found my Magnetics is wrong.

    Thanks for your advice.

    Regards,
    Kenshow

  • 0 in reply to kenshow
    Guru 15520 points

    Hi Kenshow,

    I'm having similar issue during compliance test of DP83867.
    If you don't mind, can you share us how you fixed the problem?
    What do you mean that magnetics was wrong?
    Did you use magnetics which each center tap was connected each other internally,
    and can't decouple to the GND independently?

    best regards,
    g.f.

  • 0 in reply to g.f.
    Genius 3725 points

    Hi g.f.

     My problem was selection of magnetics which is 7499111121A. It is a problem that the center tap is commonly used. Also, Link-PP LPJG16314A4NL which is used K2G ICE can not use. Perhaps the same is true for the DP83869 and DP83825, which use the voltage line driver.

    Please refer to the following：
    https://e2e.ti.com/support/interface/f/138/p/745452/2753495

    The connector included magnetics is also introduced this e2e. 

    Finally we decided to change the magnetics and redesign my board.

    I hope that this helps in your design.

    Regards,
    Kenshow

  • 0 in reply to kenshow
    Guru 15520 points

    Hi Kenshow,

    Thank you for the reply and I appreciate for your support.

    I understood.
    I'm also using RJ45 which include magnetic and its center taps are
    connected on a single net.So, it seems that I need to change the RJ45.

    By the way, did you pass the compliance test after you changed to other magnetic which
    center tap can be decouple to the GND independently?

    best regards,
    g.f.

  • 0 in reply to g.f.
    Genius 3725 points

    Hi g.f.

    >By the way, did you pass the compliance test after you changed to other magnetic which
    >center tap can be decouple to the GND independently?

    Not, yet. we just planed to change them. we are investigating any other function in my current system.

    However, I heard that other customers passed the compliance test by changing the magnetic (modified the circuit) for the same problem.

    Regards,
    Kenshow 

  • 0 in reply to kenshow
    Guru 15520 points

    Hi Kenshow,

    Thank you for the reply.
    I understood.

    best regards,
    g.f.