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LME49724: Vos is out of spec

Kenji Ohno1
Genius 5095 points
Part Number: LME49724

Hi Team,

My customers have found an IC whose offset voltage is out of specification.

Vos (Max) ± 1 mV, but Vos was -5 mV.

They replaced the IC with another one, and Vos was 0.2 mV.

I would like to know the following.

 · Does Vos pass the full inspection at the time of shipping and passed?

 · If some damage is caused to the internal transistor, does the offset voltage increase?

 · How can I check if the IC is faulty?

 (For example, measure IB + and IB -, whether one of them exceeds 200 nA greatly)

Best Regards,

Kenji

  • 0
    TI__Guru* 95285 points
    Hi Kenji,

    We'll take a look at your questions and provide further feedback within the next day.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    TI__Guru* 95285 points
    Kenji,

    Vos is tested during production, and it should be within max spec value.
    There is PSpice and TINA models available of this device in case you want to test your specific use case and verify typical device performance.
    Your suggested test could help identify damage on the IC, although you can start FA analysis process through Field Apps team or distributor.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0
    Guru 140200 points

    Hi Kenji,

    an input offset voltage which exceeds the maximum specification of datasheet often is an indication for an ESD damage. The same is valid for input bias currents which exceed the maximum specification of datasheet.

    By the way, in former times there could be another cause of increased input offset voltage. When a precision OPAmp was sticked into a socket, the input offset voltage often showed deviations from the datasheet specifications. And, it had to do with the way the OPAmp was sticked into the socket. It turned out that the mechanical stress of die caused these deviations...

    So, if the printed circuit board with the OPAmp on it experiences extreme mechanical stress after the soldering, this could also cause a shift of input offset voltage.

    Kai