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Original question:

DP83848I: Difference between DP83848I and DP83848J

DP83848K: Center tap of network transformer

Naizeng Wang
Expert 4690 points
Part Number: DP83848K

Hi team,

There is no chassis ground in customer's system. Can we leave TXOCT and RXOCT unconnected? If TXOCT and RXOCT must be grounded, can we connect them together to a virtual(floating) ground?

Thanks a lot!

Naizeng Wang

  • 0
    TI__Genius 11725 points

    Hi Naizeng,

    Just to clarify for myself, this not a screenshot from the customer system? I see a Chassis Ground in this diagram.

    If customer does not have a Chassis or Shield Ground, what is the ground used for cable connector? RJ45 should have ground pins. 

    Thank you,

    Nikhil

  • 0 in reply to Nikhil Menon
    TI__Expert 4690 points

    Hi Nikhil,

    You are right. It's a picture from our EVM user's guide. They don't use RJ45 in their application. They only use four wires TX+ TX- RX+ RX- to communicate with other devices. I know it's not a typical application. Could you give some advice about the connection of center tap?

    Thanks,

    Naizeng

  • 0 in reply to Naizeng Wang
    TI__Genius 11725 points

    Hi Naizeng,

    I am looking into this application and will provide additional feedback by tomorrow.

    Thank you,

    Nikhil

  • 0 in reply to Nikhil Menon
    TI__Genius 11725 points

    Hi Naizeng,

    To further clarify, the MDI output is directly connected to another device on the same PCB, correct? Are there DC blocking caps along the MDI lines between devices?

    We would still recommend using a Bob Smith Termination to ground for the magnetics. As this is not a typical application, we have not characterized this and cannot guarantee it's performance. We would recommend to do your own testing to verify this setup.

    Thank you,

    Nikhil