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DRV8834 - non-PWM mode?

figsys
Prodigy 20 points
Other Parts Discussed in Thread: DRV8834

Hi,

Is it possible to configure DRV8834 to control the H-Bridge directly and not PWM the current? Not clear if Phase/Enable Mode does this or not. Need to be able to fall back to non-PWM mode due to possible electrical interference with other sensitive circuitry.

On a related question, can the base PWM 42 kHz frequency be raised?

Thanks!

  • 0
    TI__Guru** 114905 points

    Hi Gary,

    Can you explain what you mean by control the H-Bridge directly? What is your application?

    If you are trying to set the H-Bridge on with no current limits this can be done by setting the sense resistors to 0 Ohms. This will allow the H-Bridge to drive the motor at full current until either an overtemp or overcurrent occurs. Using the device in this mode requires setting the CONFIG pin to a logic low.

    Please refer to page 12 of the datasheet for details on how to control the H-Bridge outputs in Phase/Enable Mode.

    If CONFIG is set to a logic low and the sense resistor is set to 0 Ohms, the PWM frequency is effectively lowered to 0. There is no ability to raise the PWM frequency.

     

  • 0 in reply to Rick Duncan
    Prodigy 20 points

    Hi Rick,

    By directly I meant to fully turn on the phases of the stepper motor at 100% current and no modulation. In index mode the current is set to +/- 71%. Looks like this can be accomplished by setting the PWM frequency to 0 and using Phase/Enable mode (CONFIG 0) with sense at 0 ohms?.

    Thanks,

    Gary 

  • 0 in reply to figsys
    TI__Guru** 114905 points

    Hi Gary,

    Yes, setting the PWM frequency to DC, using Phase/Enable mode, and sense resistor at 0 Ohms will allow you to directly control the phases at 100% with no current chopping.

    As stated earlier, this assumes that you remain within the temperature and current limitations of the device.