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DM816x Absolute Maximum Ratings

RY9983
Guru 10570 points


Hello,
I have an confirmation about DM8167 Absolute Maximum Ratings.

There are two or three requirements by each IO pins.
It means that we need to satisfy all of them. Right?

Best regards, RY

sprs614d.pdf (P136)

  • 0
    Guru 10685 points

    In my experience with these things it's always best to be on the safe side and match all requirements.

  • 0 in reply to _Ralph_
    Guru 10570 points

    Hi, _Ralph_.
    I think so. Thank you so much for your advice!

    Hi, TI'er.
    Are our thinking correct?

    Best regards, RY

  • 0 in reply to RY9983
    TI__Mastermind 43875 points

    Absolute max is exactly that... absolute. You should never, ever exceed the absolute max values.

    These are NOT normal operating conditions. Do NOT target these values under normal operating conditions.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Guru 10570 points

    Steve-san
    Thank you so much for your answer.
    May I have an once more question?

    I understand that we need to satisfy all absolute requirements.
    In the case of "V IO, 3.3-V pins(Steady State)",


    - We need to keep that the 3.3V pins are between -0.3V and 0.3V when it is powered off.
       Because DVDD_3P3 is 0V. Is that correct?

    On our system, first power on to the board and pull-up and pull-down are set.
    Since the DM8167 is powered off at that time, its requirement is not preferable for us...

    Best regards, RY

  • 0 in reply to RY9983
    TI__Mastermind 43875 points

    Normally it is OK for high value pull up resistors to be connected to IOs but care should be taken not to supply low impedance voltages to the IOs since they can cause internal leakage through the ESD protection circuits.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Guru 10570 points

    Steve-san,
    Thank you so much for your answer.
    Can I confirm about "Absolute Maximum Ratings" again?

    There are two requirements:
      a) V IO, 3.3-V pins (Steady State) .. MIN -0.3   MAX 3.8
      b) V IO, 3.3-V pins (Steady State) .. MIN -0.3   MAX DVDD_3P3+0.3

    This Absolute Maximum Ratings is during "Steady State". I think it means during power-on.
    I would like to clarify Absolute Maximum Ratings of during "power-off".

    During power-off:
     - We must satisfy both a) and b) of two requirements?
     Or,
     - We must meet one or the other?
     Or,
     - There are some requirements regarding current value other than a) and b)?
       (from your previous answer)

    Best regards, RY

  • 0 in reply to RY9983
    TI__Mastermind 43875 points

    Please check the power supply section of the datasheet. Section 7.1.7 has a very specific note as follows...

    "The device pins are not fail-safe. Device pins should not be externally driven before the
    corresponding supply rail has been powered up. The corresponding supply rail for each pin
    can be found in Section 3.2, Terminal Functions."

    This implies that you should not drive any signals until the power supplies are fully up and stable. Additionally then you also have the absolute maximum conditions which are to be followed at all times, not just once the device is powered up.

    My comment about driving pull up resistors is technically a violation of this, but usually the pull up power supply is also connected to the device power hence typically comes up at the same time as the power supply itself.

    BR,

    Steve