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DP83TC811R-Q1: schematic review

Dongbao Zhou
Expert 4000 points
Part Number: DP83TC811R-Q1
Other Parts Discussed in Thread: DP83TC811

Hi,

Could you help review the schematic of dp83tc811?

1. The customer would like to do MII and RMII compatible design, is that ok? For unused MAC interface pins, can we leave it to float?

2. Why need CM termination/MDI coupling and ESD shunt circuit? How does it work? Can I remove the ESD protection?

Thanks

Dongbao

  • 0
    TI__Mastermind 18425 points
    Hi Dongbao,

    Its ok to leave unused MAC interface connections floating. Please note that some MAC interface pins have strap functions associated with them. When they are left floating they will strap in their default modes. If customer wants to used non-default modes then they will still need to connected strap resistors to the unused pins.

    The CM termination circuit is a requirement as per 100BASE-T1 standard. It is strongly recommended to keep that circuit in the system. ESD protection diodes are optional and not a requirement for 100BASE-T1 operation. They are included for additional protection.

    -Regards,
    Aniruddha
  • 0 in reply to Aniruddha Khadye
    TI__Expert 4000 points
    Hi Aniruddha,

    Thanks for your reply.
    I find the CM termination circuit in OA standards, but it doesn't explain the function of CM termination circuit and how does it work, could you give me some insights?

    regards,
    Dongbao
  • 0 in reply to Dongbao Zhou
    TI__Mastermind 18425 points
    Hello Dongbao,

    The CM termination is adapted from the OA standard and it is a requirement for all PHY vendors to support it. Unfortunately there is limited literature around that network as to why its needed and how it works.

    -Regards,
    Aniruddha