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TMP116: Tmp116 stability issues

Manas Chachra
Prodigy 10 points
Part Number: TMP116

Tool/software:

Hi all, we are  facing some  issues with tmp116, we  have  outlined these  issues  below
Application Overview:
TMP116 is mounted as a component on our PCB. An aluminum plate is mounted on top of the sensor for thermal coupling. The sensor is positioned below the PCB to measure skin temperature. Used in a wearable device for continuous body temperature monitoring.
 
Issues Observed:
Temperature Deviation: When benchmarked against a calibrated thermometer, the TMP116 consistently deviates by 3-5°F from the reference measurement (Clinical Thermometer).
Restart Behavior: Every time the TMP116 is restarted (even under identical conditions and when already in contact with skin), the initial temperature readings are significantly lower than expected.
Long Stabilization Time: The sensor requires 15-20 minutes to reach stable readings, which is problematic for our application requirements.
Elevated Final Readings: Once stabilized, the sensor reports temperatures considerably higher than expected (101-102°F), even for normal body temperature conditions.
 
Technical Configuration:
Averaging: 32 samples (TMP116_AVG_32_SAMPLES)
Mode: Continuous conversion
 
Questions:
Calibration: What calibration procedures do you recommend for skin temperature measurement applications?
Stabilization: How much stabilization time is required for TMP116 post power on?
Restart Behavior: What could cause the consistently lower readings immediately after device restart?
 
  • 0
    TI__Genius 9860 points

    Hello Manas,

    Thank you for posting your concern. Are there any heat sources around the sensor that could be contributing to the temperature measurement? Isolate the temperature sensor away from other heat sources around the board and increase the thermal conductivity between the sensor and the skin. I would maximize the thermal response of the sensor by reducing the PCB area around the IC. Providing cut outs around the sensor can help increase the thermal response time or using a flex PCB. One important note when it comes to restarting the device, the sensor will restore to default settings. To further understand your issue, I can provide more guidance if you provide a log of your I2C transitions, and a diagram of how you are placing your temperature sensor.

    App Notes to Reference:

    Precise Temperature Measurements With the TMP116 and TMP117 (Rev. A) : Section 5 Measuring Human Body Temperature

    Wearable Temp-Sensing Layout Considerations Optimized for Thermal Response (Rev. B) 

    Best Regards,

    Meredith McKean