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TMP121: production spread

Vienojan Vignarajah
Prodigy 10 points
Part Number: TMP121

we have found with 11+ temperature sensors that the accuracy of the sensor is out of spec for -25DegC to +85DegC

for example if the temperature is 20DegC the temperature sensor would read 22DegC.

do you know if this is within production spread or has the accuracy of the sensor gotten worse.

  • 0
    TI__Mastermind 35825 points

    Hi Vienojan,

    Can you tell me more about how you measure the error? What instruments are used?

    thanks,

    ren

  • 0 in reply to Ren Schackmann
    Prodigy 10 points

    Hi Ren,

    On a PCB, we have two of these sensors for which we can read back the temperature for both sensors.

    As a control we use a Fluke 179 DMM with thermo couple to measure the board temperature. As mentioned above a faulty sensor will measure out of spec in comparison to the thermo couple measured temperature. But good sensor will be with 0.5DegC of the thermo couple measured temperature.

    Thanks

    Vienojan

  • 0 in reply to Vienojan Vignarajah
    TI__Mastermind 35825 points

    Hi Vienojan,

    Standard thermocouples have a spec of +/-2.2C. This is not sufficient to verify a 2C error. The TMP121 has a max specification of +/-1.5C, so two TMP121s measuring the same location could be this far apart without being out of spec. 

    All that aside, an error like this is likely caused by localized heating of some kind. Have you considered other heat sources in your system that could cause the two sensors to read differently? 

    thanks,

    ren