• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 29 subscribers
  • Views 184 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.

DRV8899-Q1: Step motor current detection

Gokhan Demirhan
Prodigy 20 points
Part Number: DRV8899-Q1

Hi,

I need to monitor the current and stop driving the motor when the current is above a threshold level. This threshold must be adjustable, and it is quite lower than the fault triggering current. I could not find a way. Fault is never triggered, but the current rises above the desired level.

  • 0
    TI__Guru 56650 points

    Hello, Gokhan,

    Do you mean an adjustable OCP threshold without pulling nFault pin low? You are right, DRV8899 OCP threshold is fixed.

    Why do you want another protection between the output current regulation and OCP?  

    Regards,

    Wang Li

  • 0 in reply to Wang5577
    Prodigy 20 points

    Hello Wang,

    My application is a camera lens cover. The range of movement is about 2 cm, and about 6 steps for my motor. I actually need to detect that the cover has stopped moving, and stop driving the motor. Otherwise the cover starts vibrating at the end points.

    I thought I could do it by monitoring the current, or errors generated by overcurrent. But DRV8899-Q1 does not give out current values, or the fault level is not settable. As I keep working on the project, it looks like I will need stall detection.

    Is there a way of detecting motor stall with DRV8899-Q1?

    Regards,

    Gokhan

  • 0 in reply to Gokhan Demirhan
    TI__Guru 56650 points

    Gokhan,

    DRV8899-Q1 doesn't provide the stall detection function. DRV8889 can support the stall detection. But, DRV8889 uses Torque_count to sense the motor speed drop to do the stall detection. If the full travel range is only 6 steps, it is hard to detect the motor speed or back EMF to do the stall detection. 

    Since DRV8899-Q1 can regulate the output current without overcurrent even in stall condition, monitoring overcurrent cannot detect the stall condition.

    I would think we can add an extra switch or Hall Effect device to do the stall detection.

    Regards,

    Wang