SNIS211D October   2019  – November 2020

PRODUCTION DATA

1. Features
2. Applications
3. Description
4. Revision History
5. Device Comparison
6. Pin Configuration and Functions
7. Specifications
8. Detailed Description
9. Application and Implementation
1. 9.1 Application Information
2. 9.2 Typical Application
1. 9.2.1 Thermistor Biasing Circuits
10. 10Power Supply Recommendations
11. 11Layout
12. 12Device and Documentation Support
13. 13Mechanical, Packaging, and Orderable Information

• DYA|2
• DEC|2

## 8.1 Overview

The TMP63 silicon linear thermistor has a linear positive temperature coefficient (PTC) that results in a uniform and consistent temperature coefficient resistance (TCR) across a wide operating temperature range. TI uses a special silicon process where the the doping level and active region areas devices control the key characteristics (the temperature coefficient resistance (TCR) and nominal resistance (R25)) . The device has an active area and a substrate due to the polarized terminals. Connect the positive terminal to the highest voltage potential. Connect the negative terminal to the lowest voltage potential.

Unlike an NTC, which is a purely resistive device, the TMP63 resistance is affected by the current across the device and the resistance changes when the temperature changes. In a voltage divider circuit, it is recommended to maintain the top resistor value at 100 kΩ. Changing the top resistor value or the VBIAS value changes the resistance vs temperature table (R-T table) of the TMP63, and subsequently the polynomials as described in the Section 9.2.1.1. Consult Section 8.3.1 for more information.

Equation 1 can help the user approximate the TCR.

Equation 1. TCR (ppm/°C) = (RT2 – RT1) / ((T2 – T1) × R(T2+T1)/2)

Key terms and definitions:

• ISNS: Current flowing through the TMP63 device
• VSNS: Voltage across the two TMP63 terminal
• IBIAS: Current supplied by the biasing circuit.
• VBIAS: Voltage supplied by the biasing circuit.
• VTEMP: Output voltage that corresponds to the measured temperature. Note that this is different from VSNS. In the use case of a voltage divider circuit with the TMP63 in the high side, VTEMP is measured across RBIAS.