Contents
1 Temperature Sensing System?? 2
1.1 Temperature Sensor Circuit? . 3
1.2 Temperature Sensor Parameters? . 4
1.3 Ideal Diode Equation??? 5
2 Temperature Sensor Accuracy? . 6
2.1 Linear Curve Fitting??? . 6
2.2 Polynomial Curve Fitting??? 7
3 Temperature Sensor Calibration Methods 8
3.1 Two Points Calibration?? 9
3.2 Three Points Calibration??? 9
3.3 No Calibration and One Point Calibration? 10
3.3.1 Average Coefficient Values?? 10
3.3.2 One Point Calibration??? 11
3.3.3 Measurement Setups??? 11
4 Calibration Setups?? . 11
4.1 Reference Sensor??? . 11
4.2 Reference Sensor Measurements?? 12
4.3 Temperature Bath??? . 12
4.4 Package Junction Temperature?? 13
5 Self-Heating Effect?? . 13
6 Example Code. 14
References? . 15
Appendix A Sample Part Measurement Data 16
Appendix B Temperature.c Source Listing? 17
List of Figures
Figure 1. MSC121x Intelligent Temperature Sensor? . 2
Figure 2. Block Diagram of Temperature Sensor? 3
Figure 3. MSC Vtemp and Measurement Accuracy?? 7
Figure 4. Increasing Accuracy with Calibration Complexity? . 9
Figure 5. Slope and Intercept Coefficient Histograms for 6 Samples??? . 10
Figure 6. Temperature Measurement Error for 6 Samples?? 10
Figure 7. RTD 5 Wires Configuration?? . 12
Figure 8. Heating Effect from Clock Frequency Change 13
Figure 9. Self-Heating Effect from Power Supply Voltage Change. 13
List of Tables
Table 1. Diode Equation Parameters??? 4
Table 2. Temperature Sensor Slope and Intercept Coefficients 5
Table 3. Temperature Sensor Calibration Complexities vs. Precision??? . 8
Table A?1. Sample Part Measurement Data? 16