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DRV8821 Vcp Issue

Gregory Reneff
Prodigy 10 points

According to the datasheet, Vcp should be 12V relative to Vm, however on my board I'm getting Vcp=-.7V relative to Vm, when Vm=12V.  What could account for this low voltage?  I think I'm getting some shoot through since the upper transistors of the H bridge won't shut off correctly, and there's also some chatter in the motor that lessens when I apply a higher voltage to the Vcp pin.

--Greg

  • 0
    TI__Mastermind 26065 points

    Hi Gregory

    Could you give more info to your problem? Such as schematic, and what had been done to you kits. VCP pin should be 12V higher than VM, other wise your part may be broken.

    High side transistors will not work properly without VCP voltage.

    if your hardware is no problem, there should not be VCP issues. Please check your application circuit and layout. Some basic rules are like following.

    1. VM cap and VCP, CP1, CP2 caps should be placed just near by the relative PINs. Pay attention to the cap voltage ratings.

    2. PowerPAD should be well soldered to the ground plane with wide area.

    Thanks

    Wilson

    Motor Application Team

  • 0
    TI__Mastermind 20985 points

    Yes, VCP should not be -0.7V relative to VM.  The IC could be damaged.

    Best regards,
    RE