• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 30 subscribers
  • Views 492 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8701: Input PWM caused mosfet short circuit

Annie Liu
Genius 10295 points
Part Number: DRV8701

Hi Team,

Customer has below question need your help.

We've designed a motor circuit recently, something very crazy is that it may work or get short circuit on different PCBs with the same schematic and layout.

Details here:

The power supply is shorted without motor loading, it seems like the High fet and the low fet at the same side are working at the same time.

When the duty of the signal PWM is very low like 1%~2%, it is working normally, we can test that the drive signal for MOSFET are right, when the duty gets larger, problems happen like above. And the drive signal for MOSFET become chaos and we can't test it.

We get two same circuit on one PCB, they are only diffrent on the layout.

And here are our schematic and layout, in this version, it dosen't work.

In this version, it works perfectly.

We used a 5v signal to the nSLEEP pin.

Without the PWM Input, the circuit doesn't get shorted.

Regards,

Annie

  • 0
    TI__Mastermind 37683 points

    Hi Annie,

    I think the issue is that IDRIVE is connected to GND via C41 (1uF). This will cause improper reading of the resistance on the IDRIVE pin to GND which determines the IDRIVE to use. 

    To resolve the issue, remove C41 and C40 and connect IDRIVE to directly to GND or a resistor to GND depending on the desired sink and source current from the table below. Add C41 and C40 to AVDD instead as recommended by the datasheet.

    I hope this resolves the issue.

    Regards,

    Pablo Armet