0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0

50

100

150

200

Temperature (

ƒC)

C001

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0

50

100

150

200

Temperature (

ƒC)

C001

-IN

+IN

INA821

15 V

0 V at 0°C

5 V at 200°C

25 mV/°C

-15 V

Copyright © 2017, Texas Instruments Incorporated

4.99

k

4.99

k

100

Pt100 RTD

100

105 k

801

1.18 k

REF5050

100

k

NR

GND

OUT

RG

RG

33

INA821

www.ti.com

SBOS893A – AUGUST 2018 – REVISED DECEMBER 2018

Product Folder Links: INA821

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Copyright © 2018, Texas Instruments Incorporated

9.3 Other Application Examples

9.3.1 Resistance Temperature Detector Interface

Figure 72 illustrates a 3-wire interface circuit for resistance temperature detectors (RTDs). The circuit

incorporates analog linearization and has an output voltage range from 0 to 5 V. The linearization technique

employed is described in Analog linearization of resistance temperature detectors. Series and parallel

combinations of standard 1% resistor values are used to achieve less than 0.02°C of error over a 200°C

temperature span.

Figure 72. A 3-Wire Interface for RTDs With Analog Linearization

Figure 73. Transfer Function of 3-Wire RTD Interface

Figure 74. Temperature Error Over Full Temperature

Range