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For intermediate potential of EVM-1V5

Satoshi Okamoto
Intellectual 485 points

Hello.

I'm using DM8168 on our custom board.
I was measured for each power supply is connected to the DM8168 for evaluation.
In result, I was confirmed that the intermediate potential appears to EVM-1V5.
When I study , EVM-1V5 is an intermediate potential EVM-1V0 is turned ON.
Please refer attached waveforms.

EVM-1V0 is connected only DM8168.
I believe that power is crowded around through the interior of the DM8168.
There is a problem in the intermediate potential of EVM-1V5?

Please tell me, if you know better countermeasures.

CH1:EN signal for EVM-1V5　CH2:EVM-1V0　CH3:EVM-1V5

Regards,

-okamoto

  • 0
    TI__Mastermind 43875 points

    Can you please ensure that the sequencing of all supplies is correct a per section 7.1.7 in the datasheet?

    Internally there are ESD protection paths which can be reverse biased if the correct power supply sequencing is not correctly followed.

    BR,

    Steve

  • 0 in reply to Steve Clynes
    Intellectual 485 points

    Hi, Steve
    Thank you for reply. I will answer a few questions for you.

    I am in compliance with the power sequence that are described in the section 7.1.7 .
    It is controlled by the firmware of the sub microcomputer.
    I am controlled by 20ms the transition time of each power sequence.
    It is confirmed by oscilloscope the transition time , it can be seen in the waveform above.

    There is a "1.8V" between the "1.5V" and "1-V Cnstant".
    Therefore , you can see that a transition in 40ms (20ms × 2).

    In addition, The intermediate potential can not be confirmed when the 1V does not turn ON.
    It becomes the intermediate potential when 1V is turn ON.
    It was confirmed by stepping through the firmware.

    Do you think of problem other than the power sequence ?
    There is a problem in the intermediate potential of EVM-1V5?

    Regards,

    -okamoto

  • 0 in reply to Satoshi Okamoto
    TI__Prodigy 70 points

    Okamoto-san,

        Can you provide the list of DM8168 balls connected to EVM-1V0 and EVM-1V5?

    Thanks and regards,

    Amit

  • 0 in reply to Amit Brahme
    Intellectual 485 points

    Hi, Amit
    Thank you for reply. I will answer a few questions for you.

    I created the connection map of the power pin of DM8168.
    A list of all the power that is connected to the DM8168.
    Please check the attached document.

    Regards,

    -okam7776.Power connections to the DM8168.pdfoto

  • 0 in reply to Satoshi Okamoto
    TI__Prodigy 70 points

    Okamoto-san,

       Thanks for the ballmap connection details and those look appropriate.

       The behavior you observe on EVM-1V5 during power-up-sequencing is expected is not a reliability concern.

    Thanks and regards,

    Amit

  • 0 in reply to Amit Brahme
    Intellectual 485 points

    Hi, Amit

    Thank you for reply. It was not possible to understand the content.
    I want to see the details.

    In other words , there is no issue to be a middle potential ?
    Power-up sequence I am expecting is not an intermediate potential .
    This is right as the behavior of the DM8168 ?

    EVM-1V5 is no issue even if the intermediate potential ?
    In addition , there is a issue the intermediate potential ?

    Regards,

    -okamoto

  • 0 in reply to Amit Brahme
    Intellectual 485 points

    Hi, Amit
    Thank you for reply. It was not possible to understand the content.
    I want to see the details.

    In other words , there is no issue to be a middle potential ?
    Power-up sequence I am expecting is not an intermediate potential .
    This is right as the behavior of the DM8168 ?

    EVM-1V5 is no issue even if the intermediate potential ?
    In addition , there is a issue the intermediate potential ?

    Regards,

    -okamoto

  • 0 in reply to Satoshi Okamoto
    TI__Prodigy 70 points

    Okamoto-san,

         Sorry - if the earlier reply was not clear.

    >>In other words , there is no issue to be a middle potential ?
    >>Power-up sequence I am expecting is not an intermediate potential .
    >>This is right as the behavior of the DM8168 ?

    >>EVM-1V5 is no issue even if the intermediate potential ?
    >>In addition , there is a issue the intermediate potential ?

        This behavior of intermediate potential on EVM-1V5 can occur and is not an issue for the device.

    Thanks and regards,

    Amit

  • 0 in reply to Amit Brahme
    Intellectual 485 points

    Hi, Amit
    Thank you for reply. I was possible to understand the content.

    Intermediate potential of EVM-1V5 can occur.
    but, I understand that it is not an issue for the DM8168.

    I appreciate the cooperation of Amit .

    Is there a solution to the intermediate potential of EVM-1V5?
    If there is a solution , I want tell me .

    Regards,

    -okamoto