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Original question:

DP83869HM: Signal Integrity - EYE Diagram Information Required

DP83869HM: PHY SIGNAL INTERFACE

Manoj Chate
Prodigy 180 points
Part Number: DP83869HM
Other Parts Discussed in Thread: DP83869,

Hi team,

I'm interfacing DP83869 with Microchip's KSZ9477 for PHY signals.

KSZ9477 PHY Signals operate over 2V5 as reference core voltage.

DP83869HM VDDIO is 3.3V. Does  PHY signals (Pin 1,2,4,5,7,8,10,11) operate with VDDIO as reference core voltage ?

 Will the system work correctly ?

Thanks,

  • 0
    TI__Mastermind 29890 points

    Hi Manoj,

    MDI pairs are driven with reference to IEEE 802.3 spec, not a supply on the PHY. I'm taking a look at your schematic and will provide feedback by Monday.

    Thanks,

    Lucas

    All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and it is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).

  • +1 in reply to Lucas Wolter
    TI__Mastermind 29890 points

    Hi Manoj,

    Here are my notes after reviewing your schematic:

    • I couldn't see the decoupling on all of your supplies. This is our recommended configuration. The ferrite bead I see on the 1.8V supply is still a good option to keep.

    • Is the PU resistor on MDIO installed? We recommend a 1.5k on MDIO and no PU on MDC.
    • This is the recommended configuration on the reset pin if it is not connected to a host controller.

    • Why did you choose to use a 6.04k on RX_D0 strap? You can refer to these tables for recommended strap resistor values.

    • What is the purpose of R76?
    • I don't see magnetics or an RJ45 on the 100Base-T side, or SFP for the 100Base-FX side. Can you share schematics for these?

    Thanks,

    Lucas

    All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and it is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).