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LM224A: max temp drift

Lutz Naumann
Expert 6110 points
Part Number: LM224A
Other Parts Discussed in Thread: LM2904B, LM2902

Hi Team,

we want to use the LM224A in an application where the initial tolerance can be be calibrated. We would like to have an estimate about the temp drift we have to expect. Is there any data about max temp drift numbers available or what would be a best guess? It is understood that those parameters are not guaranteed by the datasheet.

many thanks

Lutz

  • 0
    Guru 140200 points

    Hi Lutz,

    this is the best estimate:

    Kai

  • 0 in reply to kai klaas69
    TI__Expert 6110 points

    Thanks Kai,

     I was actually hoping for some idea about the drift. I know the figures of the datasheet. The max 4mA would contain initial offset plus drift. If I calibrated the initial offset I would still not know what the drift will be and have to assume the worst case. I had hoped the drift can be narrowed. Say an initial offset of 0mV will drift with 66,8uV/°V worst case to get all the way to 4mV. Would that really be the case?

    nevertheless many thanks

    Lutz

  • 0 in reply to Lutz Naumann
    TI__Mastermind 22361 points

    Hello Lutz,

    According to the datasheet spec, the absolute worst case that will still pass is -4mV to 4mV from -25C to 85C, so 8000uV/110C which gives 72.7uV/C but this a very unlikely scenario.

    However, this test is not necessarily one that is testing for drift specifically, so there may not be a 1:1 correlation to the max offset voltage test and drift.

    In a small sample bench test (~20 units) the drift mostly falls between about -8uV/C and 8uV/C. However this may not be a representative sample due to low sample size.

    If you must assume worst case, the absolute worst case would be 72.7uV/C. However if you are looking for lower max drift spec in a similar price range I would recommend LM2904B.

    Best,
    Jerry

  • 0 in reply to Jerry Madalvanos
    TI__Expert 6110 points

    Thanks Jerry,

    as we will calibrate at room temp 25°C the shift is only 60K not 110. Also because we are calibrating, assuming a box method for the spec, it would drift either -4mV or +4mV after initial calibration from my understanding. So I calculated with 4mV/60K.

    The +/-8uV are actually a good indication as another version of that silicon LM2902 is speced with 7uV/°C typical.

    LM2904B would be a god technical fit. Unfortunately it is a 2ch version only and the 4ch version of this is not available yet.

    thanks for you support

    Lutz