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TMP61

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SBOS921C – DECEMBER 2018 – REVISED SEPTEMBER 2019

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9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

The TMP61 is a positive temperature coefficient (PTC) linear silicon thermistor. The device behaves like a

temperature-dependent resistor, and may be configured in a variety of ways to monitor temperature based on the

system-level requirements. The TMP61 has a nominal resistance at 25°C (R25) of 10 kΩ with ±1% maximum

device may be used in a variety of applications to monitor temperature close to a heat source with the very small

DEC package option compatible with the typical 0402 (inch) footprint. Some of the factors that influence the total

measurement error include the ADC resolution (if applicable), the tolerance of the bias current or voltage, the

tolerance of the bias resistance in the case of a voltage divider configuration, and the location of the sensor with

respect to the heat source.

9.2 Typical Application

9.2.1 Thermistor Biasing Circuits

Figure 11. Biasing Circuit Implementations With Linear Thermistor (Left) vs. Non-Linear Thermistor

(Right)

9.2.1.1 Design Requirements

Existing thermistors, in general, have a non-linear temperature vs. resistance curve. To linearize the thermistor

response, the engineer can use a voltage linearization circuit with a voltage divider configuration, or a resistance

engineer can use either a voltage divider circuit with the thermistor placed at either the high side (close to supply)

or low side (close to ground), depending on the desired voltage response (negative or positive). Additionally, the

resistor can be biased directly using a precision current source (yielding the highest accuracy and voltage gain).