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DRV8353RS-EVM: Best way to let motor freewheel or coast.

Tim Flynn1
Prodigy 240 points
Part Number: DRV8353RS-EVM

Hello,

I'm design a prototype board with the DRV8353RS. I'm using it in 1x PWM mode with Hall sensors.

It is a proto design to replace a SI9979 based design.

I will likely run it in  Sync 1x PWM mode. In 6x or 3x PWM it appears straight forward to "coast" the motor.

Do I just "disable" by setting ENABLE low?

My concern is I will do some testing with "high" inertia motors and coasting would be acceptable to slow motor.Asserting Brake may be too aggressive.

  • 0
    TI__Mastermind 21805 points

    Hi Tim,

    There is a SPI register bit called COAST, which once asserted causes the outputs to all go Hi-Z. That may be the easiest way to do it. Otherwise you would have to flip the direction and ensure the motor doesn't reverse by external monitoring.

    Pulling ENABLE low takes some time to start the coasting, also it shuts down the part completely, so you would have to turn it back on again and re-initialize it.

    Thanks,

    Matt

  • 0
    Prodigy 240 points

    Hi Matt,

    Thank you.

    That should work with COAST.

    Does COAST have priority over BRAKE etc?

    Also, setting PWM to 0 and changing direction, its that similar to 2/3 braking? 2 of 3 lower fets on.

  • 0 in reply to Tim Flynn1
    TI__Mastermind 21805 points

    Hi Tim,

    The COAST bit should have priority over BRAKE.

    When you set PWM low, it will be braking two of the three 1/2-H bridges while the third will be Hi-Z. If you do this while changing the direction, I think it still operates as a brake.

    Thanks,

    Matt