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DRV8828: Application Inquiry

Renan Santos Adriano
Genius 16500 points
Part Number: DRV8828

Hello Team,

Good day.

My customer, using a DRV8828PWPR motor controller with a 33GB-520 DC motor. VM is 12V, VREF is 3.3V, directly connected to an Arduino 33 IoT's 3V3OUT pin. V3P3OUT (pin 15) is bypassed to the ground. Since the motor is rated for 100mA, they connected pins 6 and 9 (ISEN) to a 10 Ohm resistor, so the chopping current should be 3.3V/(5 * 10 Ohm) = 0.066A (66mA). When the PHASE pin (pin 20) is set to one, the motor works as expected. When the PHASE pin is set to zero, when the winding current (pins I0 to I4) goes over 50-60%, the motor stops after a few seconds (usually two or three, the amount of time varies). After it stops, the motor doesn't start working again until I reset the controller (set pin 16/nRESET to zero and then to one again).

Is there something trivial I'm missing? I'm guessing a problem with the controller because resetting it restores the situation. 

Regards,

Renan

  • 0
    TI__Guru 56650 points

    Renan,

    What is the motor ripple current?  The current regulation point is the peak current point. Would you show both winding current between Phase pin zero and one?

    Regards,

    Wang

  • 0 in reply to Wang5577
    TI__Genius 16500 points

    Hello Wang,

    Good day and thank you for this response. A few clarifications from my customer: (1)Are the ripple current and pick current the same thing? Anyway, where should they measure it? (2) Is the winding current the one going through the motor? Are we talking about the current that goes from pins 5 and 10 (OUT1) to pins 7 and 8 (OUT2)?

    Regards,


    Renan

  • 0 in reply to Renan Santos Adriano
    TI__Guru 56650 points

    Renan,

    Please check the current from OUT1 to OUT2.

    " when the winding current (pins I0 to I4) goes over 50-60%, "

    How did you measure the current?

    Regards,

    Wang

  • 0 in reply to Wang5577
    TI__Genius 16500 points

    Hello Wang,

    Sorry for the delay, My customer wanted to test everything as thoroughly as possible.
    They switched the resistance to 6.66 Ohms (three 20 Ohms resistors in parallel), so the maximum output current should be 99mA. They tested four different motors (of the same model) and all of them gave me the same values. The motors they tested with a little aluminum cog attached, that they slowed down with their hands trying to simulate a load change.
    Measuring the winding current, they found values around 60mA (57~63) for both phases when at full speed (all the input bits set to high) and no-load (just the aluminum cog). They registered an initial peak around 100mA and an increase in current with a maximum around (again) 100mA when interfering with the motors. 
     
    The issue also slightly changed behavior:
     
    • when they put the multimeter between the controller’s output and the motor, the motor never stops
    • the motor stops only when the phase is low, and for a few times (3-4 times), then it starts working normally
    • it happened some times that the motor didn’t stop right way (after a few seconds), but after 10-20 seconds of running
     
    Any idea?
    Regards,
    Renan
  • 0 in reply to Renan Santos Adriano
    TI__Guru 56650 points

    Renan,

    Please share the waveform when they think it is abnormal.

    Regards,

    Wang