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  • TI Thinks Resolved

DRV8834: Output waveform issue

Intellectual 645 points

Replies: 15

Views: 322

Part Number: DRV8834

Hello Team,

I am facing the following issue with DRV8834

We are driving a stepper motor with it,

The inputs are :

Indexer Mode with M0, M1 = 0

STEP pulses: 15 PWM pulses, 208Hz frequency,

VM = 3.7 ~ 4.2V

Enable pins driven low during the PWM inputs.

Schematic :

I measured the output waveform across Aout1 and Aout2 and i found one spike after all counts it makes an extra count for my stepper motor.

  

Please suggest a way to remove this spike.

Your time is highly appreciated.

Please let me know if you need any other information.

  • In reply to Wang5577:

    Wang,

    Thank you for your reply.

    I did add 100uF capacitor at the VM, but the spike is still there.

    At this time the Adecay pin is connected with ground through 51K

    Please let me know if you require any more info.

    Regards,

    Mit

  • In reply to MIT SHAH:

    MIT,

    If the winding current is not zero, the OUTx will be always one forward body diode voltage higher than VM. It is normal to me.

    Adding the more input capacitance just keep the VM voltage not been pushed to too high to damage the IC.

    Best Regards,

    Wang Li

    Motor Drive Solutions

  • In reply to Wang5577:

    MIT,

    Our senior engineer also looked this post and pointed to me the waveform showed the voltage going negative. So, when you do the measurement, you may put probe's ground reference on one side of the output.  That could show two body diode voltage difference between normal output voltage and the overshoot voltage after you stop the motor. 

    Best Regards,

    Wang Li

    Motor Drive Solutions

  • In reply to Wang5577:

    Wang,

    Thank you for your input.

    Yes we do measure the output waveform between Aout1 and Aout2.

    Do you suggest that we need to take the DSO's ground reference to PCB's ground instead of Aout2?

    Best Regards,

    Mit shah

  • In reply to MIT SHAH:

    MIT,

    It is OK to use AOUT2 as reference. To me, I just think the PCB's ground or IC ground is a good reference when we discuss the over voltage issue.

    Best Regards,

    Wang Li

    Motor Drive Solutions

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