DMAR
Other Parts Discussed in Post: TMP117
For the highest accuracy temperature measurement, system designers have traditionally had only one option: platinum resistive temperature detectors (RTDs) such as the PT100 or PT1000. Highly linear and interchangeable, RTDs are available in a wide range of accuracy classes as defined by International Electrotechnical Commission (IEC) and Deutsches Institut für Normung e.V. (DIN) standards down to ±0.03°C of error at 0°C. However, achieving this level of accuracy with RTDs doesn’t come easily.
To attain the highest accuracy available with RTDs, it often takes anywhere from hours to days to carefully select and simulate expensive precision components surrounding the RTD. A designer must also be extremely diligent with the board layout to avoid resistance mismatches which can easily skew measurements.
Despite a designer’s meticulous efforts, the acquisition circuitry can easily add 0.5°C to 1.0°C of measurement error, dwarfing the inherent accuracy of the RTD itself. To achieve accuracy that is close to what the RTD can offer, the only option is the time-consuming and expensive process of calibrating each unit in production.
Save time in your design | |
![]() |
Learn more by reading the application note, “RTD Replacement in High Accuracy Sensing and Compensation Systems Using Digital Temperature Sensors.” |
To tackle the design challenges in using RTDs, TI recently introduced the TMP117 family of digital temperature sensors which provides accuracy comparable to Class-AA RTDs while dramatically simplifying design efforts. As shown in Figure 1, the TMP117 offers accuracy of +/-0.1oC from -20oC to 50oC and 0.3oC accuracy across a full operating range of -55oC to 150oC with no calibration during manufacturing required.
Note: The RTD lines represent error of each accuracy class per IEC 60751 and does not include measurement error or calibration which will impact the final system-level accuracy.
From a design stance, the contrast between designing with an RTD verses an IC temperature sensor couldn’t be starker (see Figure 2).
VS.
By combining the sensor and analog-to-digital converter (ADC) onto a single chip, a digital temperature sensor like the TMP117 dramatically simplifies many of the most time-consuming and difficult aspects of RTD designs and provides a direct temperature readout across an I2C interface. Table 1 shows a detailed comparison on the design efforts needed between the two technologies.
![]() |
For an alternative to platinum RTDs for applications that need the highest accuracy, check out the TMP117. Its integration provides unprecedented simplicity, while also simplifying and reducing costs at production.
See how the differential temperature measurement (DTM) subsystem of heat and cooling meters provides a fully digital alternative to thin-film platinum RTD sensors using the “Replacing platinum RTD sensors with digital temperature sensors” reference design.
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATASHEETS), DESIGN RESOURCES (INCLUDING REFERENCE DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS” AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable standards, and any other safety, security, or other requirements. These resources are subject to change without notice. TI grants you permission to use these resources only for development of an application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of these resources.
TI’s products are provided subject to TI’s Terms of Sale (www.ti.com/legal/termsofsale.html) or other applicable terms available either on ti.com or provided in conjunction with such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for TI products.
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2023, Texas Instruments Incorporated