SBOU246 January   2022 TMP61 , TMP61-Q1 , TMP63 , TMP63-Q1 , TMP64 , TMP64-Q1

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 NTC Thermistor Versus TMP6 Linear Thermistor Family
    2. 1.2 NTC/Linear Thermistor TCR
    3. 1.3 NTC Versus Silicon-Based Linear Thermistor Trade-Offs
    4. 1.4 TMP6 Accuracy
  3. 2Typical NTC Thermistor Design Considerations
    1. 2.1 Voltage-Biased NTC Thermistor Network
    2. 2.2 Pinouts/Polarity
    3. 2.3 Converting NTC Thermistor Hardware Design to TMP6 Linear Thermistor Design
    4. 2.4 Simple Look-Up Table
  4. 3Software Changes
    1. 3.1 Firmware Design Considerations
    2. 3.2 Oversampling
    3. 3.3 Low-Pass Filtering in HW Versus SW
    4. 3.4 Calibration
  5. 4Design considerations for Full-Scale Range Voltage Output
    1. 4.1 Simple Current-Biased
    2. 4.2 Active Voltage-Biased
  6. 5Conclusion
  7. 6Additional Resources/Considerations
    1. 6.1 Constant-Current Source Design
    2. 6.2 TMP6 Thermistor Standard Component Footprints
    3. 6.3 Dual-Sourcing Approach for TMP6 and NTC Thermistors

3.1 Firmware Design Considerations

The recommended method for calculating the temperature values from TI's TMP6 Linear Thermistor portfolio is the 4th order polynomial regression. This is the most accurate and fastest method to calculate the temperature- with no look-up table needed. Moving on to the 4th Order Polynomial TMP vs. Res tab, we find both the Quartic Function and Regression model which provide the 4th order polynomial for the calculated temperature/resistance of the device.

GUID-21F07560-8931-4ED7-AF77-8912BA90A132-low.pngFigure 3-1 4th Order Polynomial.
Here we provide the C code that can be readily implemented into a system designers software to calculate the temperature of the TI TMP6 linear thermistor chosen.

GUID-9B3E2A68-4A7B-4451-AE5D-65331A4ACC5D-low.pngFigure 3-2 4th Order Polynomial C Code.