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DP83867IR: Drive control for RXC and RX data

Kalpesh Diyora
Prodigy 170 points
Part Number: DP83867IR

Hi TI team,

We are using DP83867 phy in our compute module.

We did used 33R series resistor before and having more rise time. We did replaced it to 0R and TXC lines from soc is resolved from SI issue but no benefit on RXC line. Do we able to increase drive level in DP83867 part on RXC and RX pins (Pin32 to 36 & Pin38)?

  • 0
    TI__Mastermind 25945 points

    Hi Kalpesh,

    We were able to tune the IO impedance of MAC interface using register 0x0170 bit [4:0]. Could you try this out to see if this would help with your application?

    May I also ask what MAC interface are you using? If you are using RGMII interface could you also double check if you have did shift mode on RX clock signal? 

    --

    Thank you,

    Hillman Lin

  • 0 in reply to Hillman Lin
    Prodigy 170 points

    Hi Hillman Lin,

    Default impedance is fix to 50Ohm on 0x0170 bit [4:0]. We will still try to adjust it.

    Mode is RGMII. RGMII mode kept default to aligned mode.

    TXC, RXC waveform is as attached.

    RXC with 0ohm Series register:

    TXC with 0ohm Series register::

  • 0 in reply to Kalpesh Diyora
    TI__Mastermind 25945 points

    Hi Kalpesh,

    Thank you sharing the waveform. We will wait for your result on 0x0170 register.

    May I ask did you see any functional issue due to the RX signal? Or you are concern about the signal quality on RX lines

    Could I confirm where did you probe the signal? Near the PHY side or MAC side?

    --

    Thank you,

    Hillman Lin