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Original question:

DRV8305: IC and VDRAIN resistor burnt at high current

DRV8305: IC burn when starting to PWM

Al J
Prodigy 190 points
Part Number: DRV8305

When starting to drive the MOSFETs, the IC just died with heavy smoke. Please see in the image that it's the PVDD pin and track what's affected as well. Any ideas of what's happened?

  • 0
    TI__Genius 14485 points
    Hello Al Jet,

    Are you operating the device within the Recommended Operating Conditions from the datasheet? Is it possible that any of the pins were shorted during soldering? This device has many protection features, so usually it shuts down the before any bad damage happens.
  • 0 in reply to James Lockridge19
    Prodigy 190 points
    Hi,

    Running at 24V from a PSU limited to 15A, so that should not be a problem.

    Although the picture is a bit blurry, soldering is OK. Also, if is was anything related to soldering, it should fail at power up, not when PWMing, right?

    Any other ideas?
  • 0 in reply to Al J
    Prodigy 190 points
    Running the gates @500mA and 1us. Are there any components that would have to be changed (such as CP caps) or any other differrence from the application schematic in the datasheet?
  • 0 in reply to Al J
    TI__Genius 14485 points
    Al,

    If you follow the datasheet recommendations for layout, external components, and recommended operating conditions, there should not be a failure. Have you experienced this on multiple boards? Do you experience this when the motor is disconnected from the board?
  • 0 in reply to James Lockridge19
    Prodigy 190 points
    James,

    Only tried with one board (design), but same result with and without load, so that does not seem to influence and I am still wondering where does that overcurrent (which seems quite evident to me) come from.

    Thanks.
  • 0 in reply to Al J
    Prodigy 190 points

    Hi,

    Also, noticed having a look at the BOOSTXL dev bard that VCPH cap is rated for the bus voltage (although it's tied to PVDD), instead of 16V as suggested in the datasheet. Is there any reason for doing that?

    Thanks.

  • 0 in reply to Al J
    TI__Genius 14485 points
    Al,

    I don't think there was any particular reason that the applications engineer who designed the DRV8305 BoosterPack decided to use a VCPH cap with a higher voltage rating. It might have been used somewhere else on the board, so they just reused the part number.

    Can you check for shorts on the charge pump pins? If VCPH, CP2H, or CP1H short to ground, the PVDD pin might sink current to ground. PVDD may also sink current to ground if CP1L and CP1H are shorted together. Also, please check if CP2L and CP2H are shorted together.