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Original question:

DRV8839: We are checking the performance between DRV8839 and DRV8837.

DRV8839: Motor Drivers Forum

Denish Limbachiya
Intellectual 530 points
Part Number: DRV8839

Hello Sir/Madam,

Nice to E-Meet with you.

First kindly find my attached schematic for verification.

My query is the motor does not properly working when it got external supply at the high-speed level of motor

So kindly give your inputs for the same.

  • 0
    TI__Guru 56650 points
    Denish,

    When the motor is at high speed, the EMF is also high. Would you increase VM voltage to see if it can work with high-speed?
  • 0 in reply to Wang5577
    Intellectual 530 points

    Hello Wang Lee,

    Thanks for your inputs,

    No, I can,t increase my motor voltage

    Because the system has only one power source only battery and my motor working voltage is only 3.3V.

    But during testing, I absorb there is inrush current for short duration which causes of reset problem in a motor.

    So for attending this inrush current, I have to increase VM pin bypass capacitor as per my best of knowledge.

    In our datasheet TI suggest 1UF cap with a 0.1uF cap so can I increase the value of 1uF cap for resolve this issue?

    Thanks,

    Denish.

  • 0 in reply to Denish Limbachiya
    TI__Guru 56650 points
    Denish,

    Yes. You can try to add more VM capacitors.
    But, let us confirm this OCP issue.
    a. do you see the input voltage crash when the inrush current is happened?
    b. does DRV8839 try to start every 1ms?
  • 0 in reply to Wang5577
    Intellectual 530 points

    Yes, that's true,

    Currently, when i add more values capacitor we succeed to reduce inrush current issue.

    But before that when i used 1 uf capacitor maybe driver ic restart for 1 second because after that system will act as actual.

    So i ad 47uF capacitor instead of a 1uF capacitor for resolve this issue.

    Kindly confirm that's true or not?

    Thanks,

    Denish

  • 0 in reply to Denish Limbachiya
    TI__Guru 56650 points
    Denish,

    According to your description, I would think it needs 47uF capacitor because all the discussion is based on the VM input voltage is stable. If the startup current needs more input capacitors to hold VM stable, we need to add them.
  • 0 in reply to Wang5577
    Intellectual 530 points

    Dear Sir,

    Thanks for your inputs.

    Ok noted.

    I do that and i found perfect output thanks for your inputs.

    Thanks,

    Denish