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DP83TG720S-Q1: Will 1.1V core voltage work well?

Frank H
Intellectual 2710 points

Part Number: DP83TG720S-Q1

Tool/software:

My customer is planning to use the DP83TG720S.

As core voltage they have 1.1V, which is at the high end of the specified operating range. During some short load adjustments of the 1.1V DC/DC the supply voltage can go up to 1.15 or 1.2V. This seems to be covered by the abs max specs as far as I can see.

Do you expect performance degradation by this behavior or even a stop of the communication?

I think they are mainly worried about possibly losing the communication link. Is there anything that they need to consider?

Thanks!

  • 0
    TI__Mastermind 28072 points

    Hi Winnie,

    Functionality is not guaranteed outside of the recommended operating conditions (ROC). VDD1P1 has ROC of 1.21V maximum. If voltage is above 1.21V then PHY may not function properly. However, damage will not occur until 1.4V as you saw in the absolute maximum specification.

    Thanks,

    David

  • 0 in reply to David Creger
    TI__Intellectual 2710 points

    Hello David,

    I assume you mean VDD1P0 instead of VDD1P1? From looking at the datasheet I can not find the 1.21V anywhere. Where does it come from? I all I can find in the recommended operating conditions (page 11) is 1.1 max recommended max operating range.

    I have seen that the the VDD1P0 Sensor goes up to 1.2V. Maybe this is where your number comes from?

    Thanks

    Frank

  • 0 in reply to Frank H
    TI__Mastermind 28072 points

    Hi Frank,

    My sincere apologies, I had mistaken which PHY you were using.

    For DP83TG720, recommended operating conditions are shown in section 6.3 (see below).

    VDD1P0 supply must be maintained inside the range of [0.95,1.1]V to ensure correct functionality. We cannot ensure functionality when voltage rises above 1.1V.

    Thanks,

    David

  • 0 in reply to David Creger
    TI__Intellectual 2710 points

    Hello David,

    thanks for your response. Do you have any experience of what might be happening if the core 1.0V supply is slightly exceeding 1.1V?

    While I have recommended an LDO to stabilize supply, your experience would still be valuable to share with the customer.

    Thanks

    Frank

  • 0 in reply to Frank H
    TI__Mastermind 28072 points

    Hi Winnie,

    Analog blocks of PHY will be operating on an unexpected voltage which may effect EMC and other compliance performance. Thank you for recommending the LDO to stabilize the voltage.

    Thanks,

    David