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LM98640: single power supply behavior

Matth. B.
Expert 1135 points

Part Number: LM98640

Hi,

I have a question regarding the power supplies of the LM98640.

Is there any reliability issue if the component is powered during a long time by only one power supplies (1.8V or 3.3V)?

Thanks

Matthieu Baque

  • 0
    TI__Mastermind 18275 points
    Matthieu,

    Thank you for your post. I have assigned the appropriate applications engineer to your post and they will get back to you soon.
  • 0
    TI__Expert 4940 points

    Hi Matthieu,

    I would say yes, but I have to do more investigations since I don't know all the implications.

    Best is to avoid this situation, TI does not guaranty the integrity of the part in these conditions.

    Do you have additional power sequence details, what supply and when is off?

    The part is powered on with one supply or the supply is disconnected during normal operation?

    Thank you,

    Costin

  • 0 in reply to Costin Cazana
    Expert 1135 points
    Hi Costin,
    This situation is not a normal condition but during our tests, it is possible to disconnect one supply (without any preference) while the component is ON.
    And in this case we need to be sure that we don't affect the reliability of the component.

    Thanks
    Matthieu Baque
  • 0 in reply to Matth. B.
    TI__Expert 4940 points
    Hi Matthieu,

    To my knowledge this power condition has not been tested or simulated, it is hard to say yes .
    Based on limited info I have regarding this,I don't think it is an issue.
    Can you set the power down mode before disconnecting the power supply?

    Best Regards,
    Costin
  • 0 in reply to Costin Cazana
    Expert 1135 points

    Hi Costin,

    We are not able to set the power down before disconnecting the power supply because it's not a nominal case, it's in case of a fault of one power supplies.

    I understand it's difficult to answer. If there is no technical issue at first glance, we will perhaps test it but I'm afraid that we are not able to check the impact on the reliability of the component.

    Matthieu Baque

  • 0 in reply to Matth. B.
    TI__Expert 4940 points

    Hi Matthieu,

    Besides the reliability concern, my other concern is the risk of a soft latch-up. Since power sequence is random, it can happened after the part has been programmed,

    when power is restored it will not start with registers set to default. My suggestion is to power it down before power up, this way it will start from an known state.

    Regards,

    Costin

  • 0 in reply to Costin Cazana
    Expert 1135 points

    Hi Costin,

    When we lost one power supplies, we always shutdown all power supplies of our board before restart so it will be not issue about that.

    Thanks

    Matthieu Baque