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Original question:

DRV8434A: Driver always faulting few seconds after motor start for unknown reason

DRV8434A: Conditions for recovering from thermal shutdown（OTSD）

Shinichi Inoue
Guru 21566 points
Part Number: DRV8434A

Dear Specialists,

My customer is evaluating DRV8434A and has a question.

I would be grateful if you could advise.

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When we conducted a short circuit test between the AOUT1 output of the stepping motor driver DRV8434APWPR and GND, we confirmed that the behavior differed from what was expected based on the data sheet.

Could you please advise what is the cause?

<Results confirmed by short test>
 It was confirmed that the AOUT1 output was immediately shut off (H bridge stopped) as per specifications due to short circuit detection, and nFAULT became Low.

However, after removing the short condition, the H-bridge returns to normal operation, as described on page 22 of the DRV8434A datasheet (below).
I expected that nFAULT would also return to Hi, but the AOUT1 output continued to be cut off and nFAULT also remained Low.

It was confirmed that by turning off the VM (24V) power and then turning it on again, the H bridge returned to normal operation and nFAULT also returned to Hi.

We considered the possibility that thermal shutdown was activated from the E2E post.

Because the thread I referenced, it seems to be restored by resetting the power.

However, the data sheet states that it will automatically return when the thermal shutdown conditions are removed, which does not match the actual operation.

Is it possible that the description（7.3.9.6 Thermal Shutdown (OTSD） and Table7-7. Fault Condition Summary)  is incorrect?

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I appreciate your great help in advance.

Best regards,

Shinichi

  • +1
    TI__Mastermind 18295 points

    Hi Shinichi,

    You are correct there is an error within the datasheet. Both the OCP and the TSD faults are latched. To recover from latch, you can short cycle nSLEEP with a pulse between 20us and 40us wide.  This will clear the fault but avoid putting device into the actual sleep state.  This will be a much faster recovery. I apologize for the confusion this may have caused.

    Best regards,

    Keerthi

  • 0 in reply to Keerthivasan Kumanan
    Guru 21566 points

    Hi Keerthi,

    Thank you for your reply.

    I understand the OCP and the TSD are latched.

    I'll share this information with the customer.

    The current sentence does not reflect reality. I think everyone misread. I would like the datasheet to be changed in the next revision.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi