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BOB SMITH TERMINATION AT PHY SIDE

prabakaran P
Prodigy 40 points

Hello Team,

In one of my 1G Ethernet (Using Intel's I210 (PCIe to 1G PHY) IC)  design, In magnetic Transformer  I have made BOB SMITH Termination at PHY side instead of Cable side.

i. Does it impact functionally?

ii. If yes, Can i disconnect all four resisters and capacitors?

iii. Else, Suggest me appropriate solution as I made the PCB fabrication.

I have attached my Sch file herewith.

Note: Currently i am not getting Ethernet Link while connected to another network device. i.e., No eth detection.

Regards,

Prabakaran P

  • 0
    TI__Mastermind 24885 points

    Hello Prabakaran,

    Are you using a particular ethernet phy device from TI? 

    Maybe I can better route you to the right team if you can help to provide which TI device is interfacing with your ethernet transformer and termination.

    Best,

    Michael

  • 0 in reply to Michael J Schultis
    TI__Mastermind 24875 points

    Hi Team, 

    Bob smith termination is mainly used for impedance matching on the cable. Therefore, it is important to have bob smith termination on the cable side to reduce the reflection noise of the signals. Without Bob smith termination would heavily effect the signal quality and result in not linking. Therefore, we highly recommend to have bob smith termination on the cable side.

    Here is the Schematic connection recommendation:

    --

    Sincerely,

    Hillman Lin

  • 0 in reply to Hillman Lin
    Prodigy 40 points

    Hello Hilman Lin,

    Thanks for your response.

    Is there any Possibilities to bypass (or Ignore) Magnetic as I made Bob Smith termination Wrongly (i.e., terminated at PHY side instead  Cable side).. Because, the PCB got assembled and we are in Testing stage.

    I need your support.

    Kindly do the needful,

    Regards,

    Prabakaran P

  • 0 in reply to prabakaran P
    TI__Mastermind 24875 points

    Hi Parbakaran,

    This is unfortunate to hear. One possible way you could try is changing the PHY side center tap to 0.1uF on all the center tap to see if you are able to get a link up. There is no guarantee this would work because we the reflection noise coming from the cable side is really high that will result bad signal quality.

    We still highly recommend changing the schematic.

    --

    Sincerely,

    Hillman Lin

  • 0 in reply to Hillman Lin
    Prodigy 40 points

    Hello Hillman Lin,

    Thanks for your information.

    Let's do a iteration like you said and will update you.

    Thank you,

    Regards,

    Prabakaran P

  • 0 in reply to prabakaran P
    TI__Mastermind 24875 points

    Hi Prabakaran,

    Thank you for the attempt. Feel free to let me know if you have further questions.

    --

    Regards,
    Hillman Lin