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DRV8835 Protection for Back Electromotive Force

Sadanori Kato
Guru 36540 points
Other Parts Discussed in Thread: DRV8835, DRV8848, DRV8881

Hi,

DRV8835 may be damaged by the back electromotive force which is produced from the dc motor due to the turn of the motor with the external factor.
The normal voltage for VM is about 6V.
On the other hand, the back electromotive force is above 12V.
So, could you please give us your advice to improve it in detail ?
(e.g. : the device replacement, an addition of external zenor diodes, etc.)

Best regards,
Kato

  • 0
    TI__Mastermind 26065 points
    Hi Kato,

    There are several ways dealing with this issue.

    1. Using brake (both low sides on) to stop the motor.
    2. Deceleration slowly with small deceleration rate.
    3. Add zenor/TVS to the VM line, increase the bulk caps.

    Could you get exact condition when the 12V pumping happens?

    Best regards,
  • 0 in reply to Wilson Zuo
    Guru 36540 points

    Hi Wilson-san,

    Thank you for your quick reply.
    I will inform our customer of your information, confirm that condition and get back to you.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    Guru 36540 points

    Hi Wilson-san,

    The expected conditions that the back electromotive force is produced are shown as below.

    <Expected Conditions>
    (a) The user turns the actuator by hand when controlling dc motor by using DRV8835.
    (b) The user turns the actuator by hand while dc motor is idling.

    In addition, the customer's responses are shown as below.

    1. Using brake (both low sides on) to stop the motor.
    --> Not have responded it since the dc motor is high torque.

    2. Deceleration slowly with small deceleration rate.
    --> Have responded it.

    3. Add zenor/TVS to the VM line, increase the bulk caps.
    --> It is difficult to apply it since the size of the zenor/TVS diode which supports from 1W to 2W is large.

    Could you please tell me how to protect DRV8835 from the back electromotive force ?

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Mastermind 26065 points

    Hi Kato,

    Is there a high ratio gear box between the motor and actuator, so when turing the actuator by hand, the motor is forced running very fast and causing high BEMF?

    What is the opportunity size of this case, we can look into whether we have other offer for this opportunity. What is the end application about this?

    Also we have device like DRV8848 can work at 4V to 18V.

    Best regards,

  • 0 in reply to Wilson Zuo
    Guru 36540 points

    Hi Wilson-san,

    Thank you for your quick response.
    I will suggest DRV8848 and DRV8881 to our customer.
    So, I would like to share the back ground with you, could you give me an email to the my email address ?
    We are grateful for your help.

    Best regards,
    Kato

    kato-s@clv.macnica.co.jp

  • 0 in reply to Sadanori Kato
    Guru 36540 points

    Hi Wilson-san,

    This issue has been closed.
    I greatly appreciate your cooperation.

    Best regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Mastermind 26065 points
    Hi Kato,

    Glad to know! Thank you for finding all the great motor driver opportunities. Just contact us anytime you need.

    Best regards,