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WEBENCH® Tools/DRV8836: DRV8836

miaomiao hong
Intellectual 270 points
Part Number: DRV8836
Other Parts Discussed in Thread: DRV8835

Tool/software: WEBENCH® Design Tools

Hi:

     I have some question about DRV8836  as follows:

    Equipment in 24 hours, 75 degrees high temperatures DRV8836 is broken，the motor does not work. After analysis is DRV8836 is broken,How do I exclude chip where is broken?

    Thanks very much.

  • 0
    TI__Guru** 114905 points
    Hi Miaomiao,

    In many cases, a failing device can be due to electrical overstress. This can be caused by voltage spikes above or below the rated maximums/minimums.

    Has it been determined that the device was run within specified operating limits?

    How many devices were damaged? Out of how many tested?
    What is the system voltage?
    Which mode is being used?
    How much current is running through the motor?
    How much bulk capacitance is available?
    Is the device cycling in and out of thermal shutdown?
  • 0 in reply to Rick Duncan
    Intellectual 270 points
    Hi Rick:
    There are five test equipments, one of them is broken;
    The system voltage is 3 v;
    The mode is IN/IN mode;
    The working current of the motor is 260 mA，Locked-rotor current is 450 mA;
    I'm not quite understand what you said'cycling in and out of thermal shutdown' , how do I confirm'Is the device cycling in and out of thermal shutdown'? Have introduced the datasheet? My test temperature is 75 degrees, the chip's temperature is -40~150, this should be true.
    How do I test next? THANKS.
  • 0 in reply to miaomiao hong
    TI__Guru** 114905 points

    HI Miaomiao,

    Thank you for the additonal information.

    I'm not quite understand what you said'cycling in and out of thermal shutdown' , how do I confirm'Is the device cycling in and out of thermal shutdown'? 

    >>> If it is possible to monitor the VCC voltage at the device, and the output voltages or current, look for the outputs to stop driving or the current to stop. Measure the time from the outputs/current stopping to beginning again. This time can provide a clue.A time of ~1ms is an overcurrent event. If not ~1ms, the other events could be overtemperature or undervoltage. Monitor the VCC voltage to ensure the VCC is not drooping and causing an undervoltage. At that point, the remaining fault is overtemperature.

    >>> These faults are described in  Table 1 of the datasheet.

  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points
    Hi Miaomiao,

    I forgot to ask: What is the bulk capacitor value used for the DRV8835?
  • 0 in reply to Rick Duncan
    Intellectual 270 points
    Hi Rick:
    Drive chip of three parallel capacitance between power supply and ground, Capacitance values are 0.01uf，0.1uf and 10uf;
    And the drive chip is DRV8836 rather than DRV8835.
    When I use the broken chip to drive motor, the motor vibrates without turning. Why appears this kind of phenomenon?
    And the broken chip output waveform is normal when it is not connected with the motor，but when it is connected with motor the output waveform is abnormal .