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UCC27211: Behavior related to over rating between HO and HS

Kaji@PAN
Mastermind 7775 points
Part Number: UCC27211

Hi,

I'm investigating UCC27211DDAR's devices in the market for device destruction symptoms.
I would like to ask you about the following.
For the absolute maximum ratings given on page 5 of the data sheet, the lower voltage limit of the HO pin relative to the HS pin is -0.3V DC and -2V for pulses under 100ns.
What are the symptoms of the device if this rating is exceeded?
Please tell me about the contents of the failure inside the IC, as it is also a rough outline.
(For example, overcurrent may flow into a specific circuit inside the IC, causing it to become hot and failing. The circuit may be the contents of the block diagram.)

Best regards,

  • 0
    TI__Mastermind 23005 points

    Hello Kaji,

    For this specific overstress question there is a particular internal device that can be stressed and fail.

    The driver output has internal FET's for pull up and pull down current driving. These internal FETs have parasitic body diodes just as power devices.

    If the HO output is negative relative to the HS pin, it can force current to flow in the internal driver pull down body diode. If the current is too high, or for too long it can damage the internal HO pull down transistor.

    Confirm if this answers your question, or you can post additional questions on this thread.

    Regards,

  • 0 in reply to Richard Herring
    Mastermind 7775 points

    Thank you for your reply.
    I would like to ask you an additional question.
    If the rating is over, as I asked last time, will the following situations occur?

    1. Will there be a short failure between HO and HS?
    If so, I think that it will not be possible to turn on the external transistor connected to the HO pin. (The external transistor keeps turning off.)

    2. Will there be an open failure between HO and HS?
    If so, I think that the external transistor connected to the HO pin cannot be driven off. (When the external transistor is turned on, the on state continues for a long time.)

    Best regards,

  • 0 in reply to Kaji@PAN
    TI__Mastermind 23005 points

    Hello Kaji,

    There is no way to guarantee if the internal pull down device will fail as a short or open, but we seem to see more cases where the pull down device is shorted when there is an excessive negative voltage which stresses the driver pull down FET.

    In this case the HO would not be able to turn on.

    Confirm if this addresses your question, or you can post additional questions on this thread.

    Regards,