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DP83848YB: RESET input: should software be able to drive a reset to the PHY, or is a hardware powerup reset sufficient

Tom McTaggart
Intellectual 345 points
Part Number: DP83848YB

We understand that the PHY needs an initial reset, as would typically be provided by our powerup hardware. But, should our host software also be able to reset the PHY, e.g. if it gets "hung up" during operation? Or is this over-design?

  • 0
    TI__Mastermind 19780 points
    Hi Tom,

    It would not be over-design to have the RESET line tied to the host processor. If you are severely pin limited, you could opt to leave the RESET line floating, but this is not recommended. There could be a case where the PHY stops responding and needs to be reset using the RESET signal.

    One such case is the accidental re-assignment of the PHYID which will stop all MDIO transactions from occuring until the PHY is restrapped.

    Regards,
  • 0
    TI__Mastermind 23675 points
    Hi Tom,

    When the device powers-up we actually have an internal POR (power-on-reset) circuit.
    However, you could also do a hardware or software reset after.
    I would not say it is an 'over-design' to include this. I find that a lot of customers will still do a hard or soft reset even though there is a POR circuit.

    Kind regards,
    Ross