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DRV8814: DRV8814 schematic check request

Hoi Wa Ip
Intellectual 720 points
Part Number: DRV8814

Dear TI Experts,

We designed a gaming console add-on device based on DRV8814. Below is the schematic of our design. Would you please give us comments if you see any issue regarding to the design? The primary issue that we are experiencing so far is that the DRV8814 is driving two motors, which will turn either clockwise of anti-clockwise direction based on certain conditions. However, the speed of the turning in either direction is not able to keep in constant. In short, the speed at which the motor is turning in anti-clockwise direction is much faster than the speed at which it is turning in clockwise direction. What we would like to achieve is to maintain constant speed of turning in either direction.

   

  • 0
    TI__Guru** 114905 points
    Hi Hoi Wa,

    When operating in the clockwise direction, is nFAULT asserting?
    What is the input PWM frequency?
    Can you provide scope captures of the inputs, outputs, and currents when the device is running in anti-clockwise and clockwise?
    How much current does the motor need?


    The Ichop current setting is well above the minimum overcurrent limit of 3A. Setting the current this high can create conditions where the internal overcurrent circuit variations could trigger earlier in one direction.

    Consider changing the ratio of R54/R55 to set xVREF to 0.137V or lower. This will set the current regulation at 2.75A and avoid possible overcurrent conditions.

    Another items noticed in the schematic is that C39 should be 0.47uF per the datasheet.
  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points
    Hi Hoi Wa,

    We have not heard from you in some time, and are assuming your question has been resolved. If it has not, please reply to this post or select "Ask a related question" at the top right if the post is locked.