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DRV11873: What is meant in datasheet by "high speed" application?

Dave Marinelli15
Prodigy 250 points
Part Number: DRV11873

In section 9.2.2 of the TI DRV11873 datasheet is states:

– If the motor is high current / high speed, use three Schottky diodes between the phases and ground.

What is high current?  

What is high speed?

I ran chip at 14V to drive a 3 phase motor with speed constant of about 1000 RPM/V without the above mentioned Schottky diodes.  Motor was drawing < 0.6A.  

IC failed.   PWM input is now pulled to +5V always by the DRV11873 IC.  Did failure to use the three Schottky diodes cause this? 

Thanks,

Dave

  • 0
    Prodigy 250 points
    I should have also mentioned that motor was run at 6000 RPM
    - Dave
  • 0
    TI__Intellectual 1555 points

    Dave,

    You will need to do more lab work to figure out what was the root cause of the device failure. Schottky diode recommendation is to prevent phase voltage going below - 1 which is the abs min of DRV11873. When there is much current on the phase and driver goes into tri-state period, we can see phase voltage is below negative.

    The best way is to monition phase voltage and if it goes below -1, you will need to place schottky diode.

    Thanks,

    Seil