Circuit Note

CN-0221

Rev. 0 | Page 5 of 5

RTD Measurement Test

To evaluate the RTD circuit and linearization source code, the

RTD on the board was replacement with an accurate, adjustable

resistance source. The instrument used was the 1433-Z Decade

Resistor. The RTD values are from 90 Ω to 140 Ω, which represents

an RTD temperature range of −25°C to +114°C.

The test setup circuit is shown in Figure 8, and the error results

for the RTD tests are shown in Figure 9.

1433-Z

DECADE

RESISTOR

ADuCM360

0.1µF

0.01µF

0.01µF

5.6kΩ

0.1%

10Ω

10Ω

AVDD

IOVDD

AVDD

IOVDD

0.1µF

AIN5/IEXC

AIN0

AIN1

Figure 8. Test Setup for Measuring RTD Error

0

–0.01

–25

–5

TEMPERATURE (°C)

–0.02

–0.03

–0.04

–0.05

–0.06

–0.07

–0.08

–0.09

–0.10

15

35

55

75

95

115

Figure 9. Error in °C of RTD Measurement Using Piecewise Linearization Code

and ADC0 Measurements

LEARN MORE

CN0221 Design Support Package:

http://www.analog.com/CN0221-DesignSupport

ADIsimPower Design Tool.

Kester, Walt. 1999. Sensor Signal Conditioning. Analog Devices.

Chapter 7, "Temperature Sensors."

Kester, Walt. 1999. Sensor Signal Conditioning. Analog Devices.

Chapter 8, "ADCs for Signal Conditioning."

Looney, Mike. RTD Interfacing and Linearization Using an

ADuC706x Microcontroller. AN-0970 Application Note.

Analog Devices.

MT-022 Tutorial, ADC Architectures III: Sigma-Delta ADC

Basics. Analog Devices.

MT-023 Tutorial, ADC Architectures IV: Sigma-Delta ADC

Advanced Concepts and Applications. Analog Devices.

MT-031 Tutorial, Grounding Data Converters and Solving the

Mystery of "AGND" and "DGND." Analog Devices.

MT-101 Tutorial, Decoupling Techniques. Analog Devices.

ITS-90 Table for Type T Thermocouple.

Data Sheets and Evaluation Boards

ADuCM360/ADuCM361 Data Sheet

ADuCM360/ADuCM361 Evaluation Kit

ADM3202 UART to RS232 Transceiver Data Sheet

ADP120 Data Sheet

ADP1720 Data Sheet

REVISION HISTORY

5/12—Revision 0: Initial Version

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