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Original question:

BQ79718-Q1: BQ79718-Q1 AVDD pin issue

BQ79731-Q1: AVDD pin of BQ79718V-Q1 is not working

?? ?
Prodigy 30 points
Part Number: BQ79731-Q1
Other Parts Discussed in Thread: BQ79718V-Q1

Tool/software:

This is about BQ79718V-Q1 question.

There is no BQ79718 in Part number fields. so I filled in BQ79731.

I'm verifying voltage sensing etc. But suddenly AVDD doesn't turn on.

LDOIN is 6.5V and NPNB is around 7~8V.

I send wake tone via iso-comm but AVDD is 0V.

What are the possible reasons why AVDD is shutting down?

Is there anything else we can check?

  • 0
    TI__Expert 4480 points

    Hello,

    There is a good chance that this is the auto-shutdown. The device will go into shutdown mode after 2 seconds without communication. This is something that can be disabled if you wish. Please reference the datasheet for the register.

    Thank you,

    Zachary

  • 0 in reply to Zachary Balov
    Prodigy 30 points

    Thank you for your answer.

    I have more question.

    If it's auto-shutdown, shouldn't it turn back on when it receives a wake-up signal?

    But it doesn't work, AVDD is 0V continuesly.

    Let me check that again.

    Is there anything else I can check?

    I appreciate for your help.

  • 0 in reply to ?? ?
    TI__Expert 4480 points

    Hi,

    Sorry, let me understand.

    Was ADC reading working and communication working correctly, then, all of a sudden AVDD no longer rises on wakeup?

    Is this seen on all your devices or just 1 device?

    Thanks,

    Zachary

  • 0 in reply to Zachary Balov
    Prodigy 30 points

    Hi,

    Q; Was ADC reading working and communication working correctly, then, all of a sudden AVDD no longer rises on wakeup?

    A: Yes, That's right.

    Q: Is this seen on all your devices or just 1 device?

    A: There are 2 ICs on the board. The ICs on that board had the same problem sequentially. All other boards were fine.

  • 0 in reply to ?? ?
    TI__Expert 4480 points

    Hello,

    If the devices were working normally and then all of a sudden stop working with the same hardware and software, and the issue is seen only on one board, it seems that there could be damage to the board or IC. Unfortunately, this isn't something that I can debug through an E2E thread. I recommend first checking the IC's power pins when you attempt to wake. Specifically:

    -BAT, AVDD, DVDD, LDOIN

    This will give you an indication as to what could be the problem.

    Furthermore, you can also check communication integrity and see if the devices are receiving the proper tones by checking the COMH/COML pins

    Thank you,

    Zachary