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DP83867IR: About Strap setting

Satoshi Okamoto
Intellectual 485 points
Part Number: DP83867IR
Other Parts Discussed in Thread: DP83867ERGZ-R-EVM

Hi There,

I use "DP83867IRRGZR".
I have some questions on the evaluation board.

Evaluation Board
Project Title:DP83867ERGZ-R-EVM
File:SV601189A_DP83867ERGZ.SchDoc

1. RX_DV / RX_CTRL is DNP for R21 and R23.
RX_DV / RX_CTRL sets auto-negotiation.
Auto-negotiation is valid only in mode 3 or mode 4.
Why is mode 1 set on the evaluation board?

2. There is a note below.
CFG4 [7] is RESERVED, is it correct?

>If the RX_CTRL pin cannot be strapped to mode 3 or mode 4, bit[7] of Configuration Register 4 (address 0x0031) must be cleared to 0.


Best regards
- satoshi

  • +1
    TI__Expert 5425 points

    Hi Satoshi-san,

    1. The intention of the resistors not being populated is so the user can populate the resistors to either mode 3 or 4 themselves. As a result, you will have to populate the straps yourself to either mode. Another approach would be to perform register writes for your configurations, but the writes will need to be applied after every power up and/or reset.
    2. CFG4[7] is not reserved. It is for internal test mode 1, which should not be activated under normal operation. If you have the RX_DV / RX_CTRL strap in mode 3 or 4, this test mode should be deactivated. If you cannot strap the RX_CTRL pin and need to use the register write approach, then the bit will need to be cleared to 0.

    Regards,

    Adrian Kam