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DRV8844: Fault when power up

Part Number: DRV8844

Hi TI expert

Use RESET&SLEEP on 3.3V, PIN ENABLE AND IN on 5.0V, when Fan power up , will fail on fault PIN.

  • Hello Li,

    Thank you for posting to the forum.

    Does the nFAULT voltage go HIGH after cycling power OFF/ON?

    Are the nRESET and nSLEEP pins turned high at the same time?

    Do you have a load connected at the output? Do you still observe the issue with no load connected?

  • Hi Pablo Armet

    nRESET and nSLEEP pins turned high at the same time, use 3.3V not 5V.but EN and IN use 5V, when use no load connect, have output voltage

  • Hi Li,

    Is it possible to do the following power up procedure: Turn ON VM supply -> set nSLEEP HIGH (3.3V) -> set nRESET HIGH (3.3V). I think the issue could be due to both nSLEEP and nRESET turning on at the same time.

    Try this test and let me know if it does not fix the issue.

  • Hi Pablo Armet

    Thanks for your feedback,we found when use 5V on reset and sleep pins, no found fails boot up, if need use same voltage on pins?

    Best regards,


  • Thomas,

    What is LGND and VNEG connected to?  The logic trip levels are with respect to LGND.  Just curious if that is the issue.



  • Hi Ryan

    LGND and VNEG tie directly, issue there, when we use 5V to on RESET and SLEEP. OK now , need more details for reasons.

    Best regards,


  • Hi Li,

    Thank you for the information.

    Can you provide the power boot up sequence?

    Is LGND and VNEG connected directly to the main board GND?

    RESET and SLEEP and the ENx and INx pins do not need to be the same voltage. As long as the input voltage is above V_IH (table below), the driver should read a logic high input. However, if LGND is offset, it could cause the driver to read a logic low input. Using 5-V gives higher margin for possible LGND offset.

    Can you measure the RESET and SLEEP pin voltages with respect to LGND?

  • Hi Pablo

    Boot up sequence 1. power VM (24V), 2. EN & IN (5V) 3. reset&sleep(3.3V).
    LGND and VNEG connected directly with the same ground plane. not difference on LGND and VNEG, Reset and SLEEP PIN is 3.3v.

    Best regards,


  • Hi Li,

    Thanks for the information.

    I don't see any issues with the boot-up sequence or grounding. Have you tried replacing the IC with a new one? or placing the IC on a new board?

    We are going to investigate this on our end. I will reach out to you if I have any other questions.

    Can you share the schematic of the driver? You can send me a private message if you don't want to share in the public forum.