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DRV8870: DRV8870 for use in single direction with MOSFET between Motor and OUT2 pin.

Will Benn
Prodigy 30 points
Part Number: DRV8870

I am working on a project where I plan to use the DRV8870 motor driver to control multiple motors (14 DC brushed motors) in a single direction. I intend to connect the DRV8870's OUT1 to the input pins of 14 motors, using a shared trace for all motor inputs. Each motor's output pin will then connect to the drain of an individual MOSFET, with the source of each MOSFET connecting back to the DRV8870's OUT2. Only one motor is to be operated at a time, and thus only one MOSFET will be active at a time.

For my application, I will not require bidirectional control of the motors, and I plan to permanently set the IN2 pin low to disable the reverse direction. I have a few questions regarding this setup:

  1. Are there any concerns or potential issues with permanently pulling the IN2 pin low in the configuration I described?
  2. Since the motors will only operate in one direction, and the output MOSFETs will not be switching but rather will either be pulled high or low, are there any asynchronous switching issues I should be aware of?
  3. Is there any additional advice or precautions you would recommend for this type of setup?

Thank you

  • +1
    TI__Genius 11410 points

    Hi Will,

    The setup that you described sounds like it should work, however be sure to protect against or watch out for shoot-through conditions. 

    It would be recommended to ensure you have enough bulk capacitance on the supply voltage for your largest motor. 

    Will the previous motor in the line-up come to a complete stop before the next motor starts spinning? 

    Best,

    David

  • 0 in reply to David Medis
    Prodigy 30 points

    I had intended to implement a short delay in the control logic before turning on a motor following the shut off of another motor.