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LMT86: Drift / long term stability

Joerdis Weiser
Prodigy 30 points
Part Number: LMT86

Hello,

I am using the temperature sensor LMT86 in my design. I started doing the FMEA and thought about the problem "long term stability" of sensors: Is the relation between the output voltage and the temperatur varying over time for the LMT86, and could you specify a value for that drift?

Thanks a lot in advance, kind regards,

Jördis

  • 0
    TI__Expert 6725 points

    Jordis,

    Let me look into this.

    -Kelvin

  • 0 in reply to Kelvin Le THS
    Prodigy 30 points

    Hey Kevin,

    thanks for replying. Look into the design? All I'm doing is connecting the temperature sensor to an ATmega128 ADC, Vcc = 5V.

    This is the connector to the sensor, RC lowpass -> ADC microcontroller. Everything is working fine, accuracy is good! My question is about the behaviour of the sensor over time: Could I expect, that it won't change, or will there be a slight change in output voltage, when the sensor "gets older"? The specified life span of the device I'm designing is 10 years, so the sensor output should not vary too much in this life span.

    I hope I could clarify my question, thanks a lot!
    Jördis

  • 0 in reply to Joerdis Weiser
    TI__Expert 6725 points

    Jordis,

    Thanks for clarifying the question.  I do not have the drift data readily available so I'm asking our team for support.  Stayed tuned.

    -Kelvin

  • 0 in reply to Kelvin Le THS
    TI__Expert 6725 points
    Jordis,

    If you look at the quality tab of our product you will see the DPPM/MTBF/FIT rate:

    www.ti.com/.../pinout-quality

    The life time test is modeled with 1000 hours at 125C and we see that the mean time before failure is 2.54x10^8 sec or ~8years. This is at a 60% confidence level. Failure is defined as when the device fails to meet any of the datasheet specs after the life time test.

    If you assume that the test condition above is a valid model for life time test, then that means that the drift is negligible since the MTBF is ~8 years and our part will meet specs within that time frame with a 60% probability.

    At this moment we do not have a specific drift spec for this device. We can only infer that the drift is negligible based on the life time test.
    Let me know if this helps.

    -Kelvin
  • 0 in reply to Kelvin Le THS
    Prodigy 30 points

    Hey Kelvin,

    thanks a lot for the link and the explanation, I guess that's all I need!
    Kind regards, Joerdis