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OPA990: Absolute maximum rating

ArTzy
Genius 17815 points
Part Number: OPA990

Hi Experts,

Seeking your assistance on this query from customer:

We are using your product OPA990 in one of our product and have found out that we potentially exceed an absolute maximum rating.
Concretely, we are injecting/drawing into/from the positive input pin (pin 3) currents peaks:
-    Peak current: ~ 20-40mA
-    Repetition frequency: 3000Hz
-    Charge per pulse: ~25nC (~ 30mA during 1us)
-    Typical temperature range: 25°C to 85°C
-    Expected life time: 30 years

Questions:
-    Is above scenario critical for the device?
-    What is the anticipated time to failure?
-    What would be the failure mechanism?

Note that we are aware that we are exceeding the absolute maximum ratings and we are not asking for any warranty, but just would like to get better understanding about the real risk in the field.

Thank you very much for your support.

Regards,
Archie A.

  • +1
    TI__Genius 15630 points

    Hi Archie, 

    Violating the absolute max rating for current on the input pins could damage the ESD structures and the input structure and it is recommended to current limit these inputs for proper operation of the device. I have attached an Apps Note explaining Op Amp ESD Structures for more information: https://www.ti.com/lit/pdf/slvaex7 

    It is difficult to determine the anticipated time to failure as this behavior cannot be predicted and can vary device-to-device. Exposing the device in these conditions beyond abs max will expect to degrade the reliability of the part. 

    Please let me know if you have further questions.
    Thank you!

    Best Regards,
    Ashley

  • 0 in reply to Ashley Kang
    TI__Genius 17815 points

    Thank you very much Ashley, for your answer.

    Can you anticipate in term of probability what would be the failing mode of those diodes (e.g. short circuit, open circuit, or just change of internal properties)? Many thanks.

    Regards,
    Archie A.

  • 0 in reply to ArTzy
    TI__Genius 15630 points

    Hi Archie, 

    It may depend on how much damage the ESD diodes sustain, but we would suspect it would show as a short circuit. 

    Also, I would like to add that for future reference, page 30 in our OPA990 datasheet recommends using current limiting and TVS diodes to prevent damage to the device for ESD events.

    Best Regards,
    Ashley