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DP83867IR: DP83867IR PCB trace length according to the data rate

nandhakumar s
Prodigy 40 points
Part Number: DP83867IR

As per the datasheet, The maximum routable distance is 6 Inches or lesser.  We using this IC in RGMII interface

1. To achieve this trace length what are the things to be taken care of. Whatever mentioned in the datasheet is sufficient?

2. What is the maximum trace length that can be achieved with respect to the different data rates. 

3.  Please suggest a suitable 1G re-timer/re-driver.

We are trying to achieve a 450mm trace length with lower data datarate. Is it possible to do so?

If there are any specific guidelines for this please share them with us.

  • 0
    TI__Genius 16030 points

    Hello Nandhakumar,

    We suggest to run IBIS simulations for more accurate signal integrity analysis. For 1G Rgmii standard, margins are narrow and other than trace length (for rise/fall signal integrity) , we have to match the traces so that skew between rx_clk and rx_* signals (and also tx_clk and tx_* signals) can be limited to around ~100ps. 

    You may search for re-drivers on ti.com as unfortunately we dont have a recommended list.

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    Prodigy 40 points

    Hi Vikram,

    Thanks,

    And also please confirm if we can swap pins like the red text in the below image.

    In our design, Phy is placed on the bottom side and a TH integrated Rj45 connector is placed on top of pcb.

    Because of this Pin swap is required to avoid vias

    AUTO-MDIX provision is available in this phy. Do we need to make changes in software or By default this will detect the signals?

    Please let me know if we can have this pin configuration as mentioned in the red text.

  • 0
    Prodigy 40 points

    Hi Vikram,

    please help us with this 

    nandhakumar s said:

    In our design, Phy is placed on the bottom side and a TH integrated Rj45 connector is placed on top of pcb.

    Because of this Pin swap is required to avoid vias

    AUTO-MDIX provision is available in this phy. Do we need to make changes in software or By default this will detect the signals?

    Please let me know if we can have this pin configuration as mentioned in the red text.

  • 0 in reply to nandhakumar s
    TI__Genius 16030 points

    Hello Nandhakumar,

    It is better to open a new thread for separate question for better trackability.

    Now regarding the pin swapping : yes this connection can be supported. You may use mirror mode strap or register configuration of reg<x0031> to enable mirror mode.

    See section 8.4.6.6 of datasheet for further details.

    --

    Regards,

    Vikram