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DRV5011: DRV5011 output stay on low after power on, while normally high

Qiang Zhang
Prodigy 10 points
Part Number: DRV5011

We have PCB with including 3 Channels of Hall sensor DRV5011 for our 3 phase DC brushless motor, see schematics I copied here. it working properly after power on, however next day we came back re-run it, found all 3 IC's output were fixed on 0V no matter how we changed magnetic polarity of rotors. We checked power supply, connection, possible short, and excluded possible big magnetic field nearby, etc. Seems only thing left was that 3 HALL ICs all failed over the night, which almost impossible in common sense. PCA was powered off during the night till next morning, room temp & environment. ICs on board not found any damage such as short or overvoltage because PN junctions looks good still. Not short found at Hall output pins of course. I was wondering if anyone here had similar issue before? any comment or suggestion please? 

  • 0
    TI__Mastermind 21510 points

    Hello Qiang,

    Thanks for posting to the sensing forum and for the information! The schematic looks fine to me, are the Hall outputs being directed back to a microcontroller?

    One thing I have seen before is sensors being damaged in BLDC applications due the abs max voltage rating is violated. Is the Vcc is connected to the motors supply? If you are running the BLDC motor and when it is coasted to a stop they can generate a large voltage. All the energy created by the motor can get pumped back to the supply, so when the Vcc supply is shared between the motor and the sensors it can cause the voltage to exceed the max allowable voltage of the sensors.

    I am not sure if this is what happened to your sensors, but it seems like a possible explanation if they were working fine the night before.

    Best,

    Isaac 

  • 0 in reply to Isaac Lara
    Prodigy 10 points

    Thanks for quick reply Isaac. Yes, output of Hall sensor going into I/O port of uC, 33ohm current limit resistors were placed between sensor output and uC I/Os. separate DC motor power supply provided, therfore any BFM voltage by motor won't be in sensor power line. 

  • 0 in reply to Qiang Zhang
    TI__Mastermind 21510 points

    Hey Qiang,

    Thanks for confirming the BEMF of the motor was not the real issue here. The next things I would recommend would be to remove the 33ohm resistor in order to separate the hall sensors from the micro. This will rule out if perhaps there is something on the microcontroller that is causing the output to stay low and we can truly isolate the devices. If you can see the output change in that instance then the problem could exist in the micro.

    Did you also confirm there was no short from VCC to GND? If the capacitor was damaged then this could have caused the short you can also monitor the current to see if its pulling more current than anticipated.

    Best,

    Isaac