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8

TMP61

SBOS921 – DECEMBER 2018

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Copyright © 2018, Texas Instruments Incorporated

8 Detailed Description

8.1 Overview

The TMP61xx series of Silicon Linear Thermistors has a linear positive temperature coefficient (PTC) that results

in a uniform and consistent temperature coefficient of resistance (TCR) across a wide operating temperature

range. They are suitable for use for temperature measurement, protection, compensation, and control systems.

Compared to traditional NTC thermistors, the TMP61xx series of devices offers enhanced linearity and consistent

sensitivity across the full temperature range. They also have robust performance due to their immunity to

environmental variation and their built-in fail-safe behavior at high temperatures. These devices are currently

available in 2-pin, DEC surface-mount, 0402 footprint compatible packages and 2-pin LPG through-hole, mini-

sized transistor-outline TO-92S packages.

8.2 Functional Block Diagram

Figure 10. Typical Implementation Circuits

8.3 Feature Description

As shown in Figure 1 and Figure 2, the TMP61xx has a good linear behaviour across the whole temperature

range, but a small non-linearity can observed as well as supply dependence as shown in Figure 3 and Figure 4.

The TMP61xx is fabricated using a special silicon process where the device key characteristics—the temperature

coefficient of resistance (TCR) and nominal resistance (R25)—are controlled using the doping level and active

region area. Also, the TMP61xx has an active area and a substrate due to the polarized terminals of the device.

The positive terminal should be connected to the highest potential while the negative terminal (which is tied to

the substrate internally) should be connected to the lowest potential. Equation 1 and Equation 2 can help the

user approximate the device resistance and TCR. Table 1 and Table 2 show the typical resistances, resistance

spread, and maximum expected error across temperature using a direct Ideal bias current or an ideal voltage

bias in a divider circuit.

R (Ω)

≈ 8504.85 + 55.08 T + 0.17 T

2

where

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T is the temperature of interest

(1)

(2)

Below are the definitions of the key terms used throughout this document:

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