• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 29 subscribers
  • Views 124 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8311: If inrush current will impact the reliability

Chuqiang Wen
Expert 5495 points
Part Number: DRV8311

Tool/software:

Hi team, 

Below waveform is measured at motor start-up period. It is the phase A current. You can see the peak is about 2.75V which represent 7.5A. 

At the beginning, the OCP threshold was set to 5A. They found the motor can not be driven correctly. Right now, the OCP threshold is set to 8A. DRV8311 will not be triggered OC. 

We would like to check with you if this 7.5A inrush current will impact the device reliability? In other words, they want to set OCP to 8A, but there have a 7.5A(higher than peak current drive recommended from datasheet) inrush current. Is this inrush acceptable for DRV8311? Or we should recommend high drive capability device in this application. 

Thanks!

Ethan Wen

  • 0
    TI__Genius 11855 points

    Hi Ethan,

    Typically if this in rush current isn’t violating any of the devices abs max violation then it should be okay, however I’d like to check with my team first to make sure I’m not missing anything. I’ll have an update in about a day or two.

    regard

    Yara

  • 0 in reply to Yara Al Shami
    TI__Expert 5495 points

    Hi Yara, 

    Could you help let me know the feedbacks? 

    Thanks!

    Ethan Wen

  • 0 in reply to Chuqiang Wen
    TI__Genius 11855 points

    Hi Ethan,

    I'll be sure to update as soon as I have the confirmation from my team.

    Thanks!

    Yara

  • 0 in reply to Yara Al Shami
    TI__Expert 5495 points

    Hi Yara,

    Please help to push the feedbacks. 

    It is pending for one week and customer need to make the decision ASAP. 

    Thanks!

    Ethan Wen

  • +1 in reply to Chuqiang Wen
    TI__Genius 11855 points

    Hi Ethan,

    The overcurrent protection (OCP) threshold and the absolute maximum peak output current refer to different aspects of the device’s operation and protection mechanisms.

    The OCP threshold is the current level at which the device detects an overcurrent condition and triggers protective actions, such as shutting down the output or entering a fault state. It is usually set higher than the normal operating current to prevent false triggering during brief transients like motor startup or rapid load changes. OCP typically allows short-duration current spikes above the absolute maximum peak rating without immediate damage, as long as the thermal and electrical stress limits are not exceeded.

    The absolute maximum peak output current is the highest current the device can safely provide through its output pins for a very brief period under ideal conditions without risking permanent damage.

    During startup or transient conditions, inrush currents can temporarily exceed the device’s peak rating. If OCP were set exactly at the peak rating, it would frequently trip during normal operation, making the system unusable. So I believe the 7.5A of in rush the customer is seeing is quite common and expected but it still could be a concern if they are regularly seeing 7.5 at start up here are some recommendations:

    Evaluate Current Duration: Measure the duration of the inrush current. If it is short (e.g., <1 ms), the DRV8311 might handle it without issues.

    Check Junction Temperature: Use thermal simulations or measurements to confirm that the DRV8311 operates within safe thermal limits during startup.

    Implement Soft Start: To mitigate inrush current, you can implement a ramp-up strategy for the motor drive, such as gradually increasing the duty cycle or voltage during startup.

    Regards,

    Yara