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DRV8308 rotor lockup

Golem Chen
Prodigy 100 points
Other Parts Discussed in Thread: DRV8308, DRV8301, DRV8313

Hi,

I'm using DRV8308 for BLDC motor application. And there is a rotor lockup feature(function) on this driver.

Is this can be disable? Or the only thing I can change is to write the register in LRTIME?

And at sddress 0x2A, what is the difference between 0:normal and 1:fault detected? Is "fault detected" means the fault will not lockup the motor?

Also, if the rotor lockup feature is always on, is there any other BLDC driver is without this feature?

Thanks.

Have a nice day.

Golem

  • 0
    TI__Mastermind 20985 points

    Hi,

    RLOCK can't be disabled.  Address 0x2A is for status outputs, so the one for RLOCK describes whether or not an RLOCK event has happened.  Most of our other BLDC drivers don't have an RLOCK feature, since they also don't have integrated commutation logic (e.g. DRV8301, DRV8313).

    RLOCK occurs when there are no transitions on the input that FGSEL is set to.  So it wouldn't be too difficult to fool it, by applying a pulse every few seconds.  Have you considered trying that?

    Also why do you want to disable it?  Do you want to keep the DRV8308 ENABLE active while not spinning the motor?

    Best regards,
    RE

  • 0 in reply to RE
    Prodigy 100 points

    Hi RE,

    Thanks for your reply.

    Our application is a robot system. And position control at joints are needed.
    In our system there will be some loading at the joint , so if we want to keep the position, we need to enable the driver to hold the joint.
    That's why we need to disable the RLOCK to hold the position.

    Yes, fooling the driver is a possible solution to use DRV8308. I have try that and the side effect is reducing the control precision.
    So far, we think it's plan B if we can't find a better solution. Because the result is not so well...

    It seems like DRV8301, DRV8313 are better solution for our application. 
    Also, In DRV8301 datasheet, it mentions that "robotics control system" is one of the applications. Is this a position control robotics?
    Or it's used on speed control system?

    Is there other drivers that you think can be used in position control application?

    Thanks,
    Have a nice day.
    Golem

  • 0 in reply to Golem Chen
    TI__Mastermind 20985 points
    Yes, the DRV8308 was designed for continuously rotating BLDCs. I think the DRV8313 or DRV8301 could work for you, and can be used for both position control and speed controlled applications.

    Best regards,
    RE