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Original question:

DRV8872: Driver current issue

DRV8872: Driver current issue

user5813940
Intellectual 675 points
Part Number: DRV8872

  In our design, the Drv8872 is used to drive the brush motor of the Parking E-lock.

  The Power of DRV8872 is provided  by a lead-acid battery, of which the standard battery nominal votage is 12V.The VM pin is coupled with a 100nF Multilayer Ceramic Capacitor  and a Y5V 47uF/16V Multilayer Ceramic Capacitor. 
  The 12V then is buckeddown to 4V then 3.3V for the system. The fault pin is pulled up to 3.3V through a 30K resistor.

  We have encountered 3 cases when testing the electric board.The phenomenon is as described as below.

  When the battery is plugged in or the 12V power is switched on, the VM part of the DRV8872 got burned!!!
   
  The part of schematic and PCB document is as below. And the highlited path is the  power line to VM PIN of DRV8872.
   
  Please give some advice for our use of DRV8872.

  • 0
    TI__Guru 56650 points
    Hello,

    Typically, a device can be damaged by over voltage spike or over current spike. To quickly understand the root cause, please provide more info:
    a. After damage, does OUT1, OUT2, VM, ISEN, IN1 and IN2 pin to ground resistance become abnormal?
    b. When the part got damage, what is DRV8872 operation condition? Such as: IN1, IN2 high or low;
    c. Would you catch the input current and voltage waveform at the input source insertion if the damage is happened at that moment?
    Also, the schematic and layout were not shown in your post. Please resend it.
  • 0 in reply to Wang5577
    Intellectual 675 points

    the U401 part is the DRV8872.

  • 0 in reply to user5813940
    TI__Guru 56650 points
    Hello,

    Are you able to answer previous questions:
    "a. After damage, does OUT1, OUT2, VM, ISEN, IN1 and IN2 pin to ground resistance become abnormal?
    b. When the part got damage, what is DRV8872 operation condition? Such as: IN1, IN2 high or low;
    c. Would you catch the input current and voltage waveform at the input source insertion if the damage is happened at that moment? "

    Also, if the part was damaged after it was powered up. Would you measure the winding current? Also, the IC was hot or not hot before damage?