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DRV8701: Active braking when not moving

Job Nijenhuis
Prodigy 10 points
Part Number: DRV8701

Hi,

We've used the DRV8701E in a design of ours. In this design, we require the motor to brake when idle, as there is a constant load attached to the motor. This mass is too high to passively brake (so the motor will start rotating by itself due to the weight). We have seen that the braking functionality only works on a moving motor. It doesn't require extra effort to initially rotate the motor by hand, it only requires extra effort to keep the motor moving. This means that in our application the load moves down, is stopped by the brake functionality, then after the motor has stopped starts moving again, and that happens until the load is on the floor. Is there a way to have the DRV8701E actively brake when not moving? So that it requires extra effort to _start_ the movement, not only to _continue_ the movement?

Thanks!

  • 0
    TI__Guru 56650 points

    Job,

    For a brushed DC motor, brake condition means short the output winding to quickly convert the motor spinning mechanical energy to short loop's heat. If the motor moves very slow, it doesn't generate a higher back EFM, the output short cannot hold its position.

    According to your description, I would think a stepper motor could fit your application. It can hold on a position if the motor drive doesn't get STEP pulse signal.