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Original question:

TMP117: Product specs: Expected operational life (hours) at specified temp range (-20C to 150C)

TMP117: Long term stability and drift parameter interpretation

Caio
Intellectual 270 points
Part Number: TMP117


Hello everyone.

My company is designing a wireless temperature sensor for industrial fridges and cold chambers. The product is sealed inside a small enclosure and runs on battery for 5 years. We are using TMP117 as the temperature sensor.

The client is asking us about temperature measurement stability and drift over these 5 years of expected product life. Bear in mind the product will run in three different temperature ranges: around -18°C, 6°C and 20°C.

The datasheet states that a drift of ±0.03°C is observed when submitting the part to 300 hours at 150°C (acceelrated aging). How can I extrapolate this data to find the expected (or maximum value) temperature measurement drift over 5 years? Can I assume that the sensor will drift ±0.03°C per year? Is this drift linear over the years?

Thank you very much.

  • 0
    TI__Mastermind 44245 points

    Hi Caio,

    The application note Calculating Useful Lifetimes of Temperature Sensors discusses the application of the accelerated aging data using the Arrhenius equation. As application temperature decreases, the high stress temperature (150C) simulates an increasingly long service life at the application temperature. At low application temperatures, the analysis predicts 5, 10 or even 100 years of use at that temperature. For an application temperature of 25C and below, the specified 150C 300 hour stress models 107 years of semiconductor aging. 

    While we have made a clear statement about the testing performed and the accuracy observed, we make no guarantee for this as evidenced by the lack of Min and Max specifications for Long-term stability and drift in the Electrical Characteristics table. 

    Thanks,

    Ren

  • 0 in reply to Ren Schackmann
    Intellectual 270 points

    Ok Ren, thank you very much.

    So I can't expect any official documentation/certificates that will support this claim, is that it?

    In any case, it is now my understanding that submitting the product to low temperatures actually increases its life expectancy and reduces it's measurement drift over time, is that correct? Note that I'm not very much concerned about life expectancy (the part ceasing to work) but on temperature measurement drift. My application dictates that the sensor cannot drift more than 0.1°C in 5 years.

    Thank you.

  • 0 in reply to Caio
    TI__Mastermind 44245 points

    Yes, I believe you understand correctly.

    The accelerated aging test, known as HTOL, is usually performed on all of our products before release. The product must still meet min/max specifications after the stress from the aging test is applied. In the case of TMP117, we are reporting in the datasheet the result of the test. This result is typically not published. 

    The stress conditions 150C and 300 hours predict 5 years of aging in a 60C application. The result of the test is that accuracy did not shift by more than +/-0.03C due to this amount of stress. 

    Thanks,

    Ren

  • 0 in reply to Ren Schackmann
    Intellectual 270 points

    Thanks Ren. That answers my question perfectly.