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DRV8329AEVM: Fault occurs after powered up

Sal Ye
Mastermind 24485 points
Part Number: DRV8329AEVM

Hi expert,

When I test on DRV8329AEVM, it shows a strange phenomenon that when INHx&INLx is input ahead of DRV powered up, DRV always make itself fault after powered up.

The specific action is below:

  1. DRV is not powered
  2. INHA and INLA are given some input (one is given high signal, etc.), others are no input.
  3. DRV gets powered on
  4. Fault occurs

The following waveform can describe the signal I used. Every time when I power up, DRV is set fault, and only when I give a quick low logic pulse to nSLEEP can I release the error.

Note1: This is the normal waveform after reset. And, Green is OUTA (SHA); pink is GHA; blue is GLA; Other INHx/INLx is no input.

Note2: OUTA is around 7V; Pink is around 7V~12V; Blue is 0V; all signal are reference to GND in EVM.

Note3: There is no load on OUTA, so it keeps high output voltage.

I have post it in the following E2E thread in case you need: https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/1187951/drv8329-pwm-control-mode-of-drv8329-pwm-generate-issue/4504175#4504175. However, I have replied many to this thread, I think it will be a bit blurry to read. Thus, I post a new thread for the new coming issue.

Do you have some comments on it, Thanks a lot.

Best Regards

Sal

  • 0
    TI__Genius 14130 points

    Hi Sal,

    Thank you for posting the Motor Driver's forum!

    I will aim to provide a response by the end of next week.

    Best,

    ~Alicia

  • 0
    TI__Genius 14130 points

    Hi Sal,

    The reason that you are getting a fault is because you are giving the INHx and INLx inputs before the DRV is powered up and ready to accept inputs. I would recommend waiting for the device to be powered on before sending any signals on the INHx and INLx pins.

    Best,

    ~Alicia

  • 0 in reply to Alicia Rosenberger
    TI__Mastermind 24485 points

    Hi Alicia,

    I have done a test that send signal after power up, yes it will run normal.

    Then, I found a interesting thing that when PVDD is higher than 7.5V, DRV will run into fault, and it can not be released (HiZ mode test).

    To find what happened, I check the voltage between BSTx and SHx. It shows below (PVDD = 7.5V; no fault here):

    Therefore, it is relevant to BSTx undervoltage fault.

    When it runs in HiZ mode, such as INHA = PWM; INLA = Low. Due to there is no load, VSHA keep the same with PVDD (In PWM mode, VSHA will be switching from PVDD to 0V). Which makes BSTA is smaller than PWM mode, then fault happen. I hope this will be helpful for DRV application.

    Best Regards

    Sal