7

TMP64

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SNIS212 – DECEMBER 2019

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7 Detailed Description

7.1 Overview

The TMP64 series of silicon linear thermistors has a linear positive temperature coefficient (PTC) that results in a

uniform and consistent temperature coefficient resistance (TCR) across a wide operating temperature range. To

fabricate the TMP64, a special silicon process is used where the devices key characteristics—the temperature

coefficient resistance (TCR) and nominal resistance (R25)—are controlled by the doping level and active region

area. Note that the TMP64 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 should be connected

to the lowest potential.

The TMP64 is different from a NTC, where a NTC is a purely resistive device, the TMP64's resistance is affected

by the current across the part and changes with temperature. In a voltage divider circuit, it is recommended that

the top resistor is kept at 47 kΩ. Changing the top resistor or the VBIAS changes the resistance vs temperature

table (R-T table) of the TMP64, and subsequently the polynomials as described in . Consult the TMP64 R-T table

section for more information.

Equation 1 can help the user approximate the TCR.

(1)

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

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•

•

•

•

7.2 Functional Block Diagram

Figure 5. Typical Implementation Circuits