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DRV8824: Fault consideration

Olrik Maier
Expert 5030 points
Part Number: DRV8824

Hi

According to EN60335 19.11.2f we have to consider an integrated circuit as a black box.

Can it be happen that  VDD of the DRV8824 is directly connected to 2 winding outputs due to an internal fault in the part.

For example:

The short circuit which would cause issues in our case would be a short from VMA to A/Boutx or from VMB to A/Boutx

Best wishes;

Olrik

  • 0
    TI__Guru 56650 points
    Olrik,

    Do you mean V3P3OUT pin or input VMx pin? DRV8824 doesn't have VDD pin.

    According to the pin out location, xOUTx pins and V3P3OUT are not adjacent pins. So, I don't have concern the open/short test can cause V3P3OUT short to output issue.

    If you mean VMx pin, xOUTx pins and VMx are adjacent pins. Even the IC is good, the bad soldering could cause the issue.
  • 0 in reply to Wang5577
    TI__Expert 5030 points

    Hi Wang,

    it's not of external failures around the part, it's when the part fails by it self. Can there be internal shorts if the part becomes somehow damaged from an inputvoltage pin to the outputs ?

    What's the behaviour of the internal FETs in case of a failure - can they get short ?

    See attached

    It's a requirement driven by VDE regularities that in failure condition it couldn't be happen that a inputvoltage has a short to the output.

    Best wishes,

    Olrik

  • 0 in reply to Olrik Maier
    TI__Expert 5030 points
    Hi Wang,

    any update ?

    Best wishes,
    Olrik
  • 0 in reply to Olrik Maier
    TI__Guru 56650 points
    Olrik,

    The FET damage could be shorted or opened when VM pin is overstressed. I think when the system senses the failure condition and motor driver is damaged/out of control, the system should add another layer independent protection to protect its self.