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DRV11873 motor start in high speed

GalS
Intellectual 410 points
Other Parts Discussed in Thread: DRV11873

When I start the motor (changing PWMIN from 0 duty cycle to any value), the motor starts in high speed, and than decelerate to the desired speed.

I have checked a motor's phase, and see that for 1% duty cycle the phase cycle is about 130Hz, and for 50% it is about 400Hz.

But in the beginning it is always about 400Hz.

I have checked Vcc, and it drops a bit only for 20mS.

Is it a problem, or part of the DRV11873 spec?

 

 

 

 

  • 0
    TI__Guru** 114905 points

    Hi GalS,

    The DRV11873 is designed to start at high speed then decelerate to the desired speed as you note.

    For reference, please see the post http://e2e.ti.com/support/applications/motor_drivers/f/38/t/274006.aspx  This provides more details on the startup procedure.

    For clarification, is the 1% and 50% referred to at the PWMIN input?

  • 0 in reply to Rick Duncan
    Intellectual 410 points

    Hi Rick,

    Thanks.

    Yes, the 1%-50% refer to PWMIN.

    BTW, the start speed is equal to the 50% PWMIN speed (regardless of the PWMIN duty cycle).