The TI TMP117 temperature sensors can replace RTDs while reducing power consumption and easing system design

By Gina Roos, editor-in-chief

Texas Instruments
(TI) has unveiled a new temperature sensor family that offers ±0.1°C accuracy
across a wide temperature range with zero calibration during manufacturing,
simplifying system design for industrial and medical applications. The TMP117
sensors
expand TI’s portfolio of digital temperature sensors
that enable designers to integrate thermal monitoring into their designs.

The TMP117 offers
Class-AA resistance temperature detector (RTD) accuracy for industrial
applications. It provides a direct readout of temperature, with no additional
linearization or acquisition error, and maintains accurate temperature over a
wide range as follows:

  • ±0.1°C from –20°C to 50°C
  • ±0.15°C from –40°C to 50°C
  • ±0.2°C from –40°C to 100°C
  • ±0.25°C from –55°C to 125°C
  • ±0.3°C from –55°C to 150°C

At a similar
level of accuracy with a platinum RTD, “engineers must select a multitude of
precision components, simulate and fine-tune the circuit, carefully lay out the
PCB to avoid impedance mismatches, develop software to linearize the output,
and calibrate each system,” said TI. The TMP117 is claimed to be the first
single-chip temp sensor to offer similar performance to platinum RTDs without
the extra development work, which reduces design complexity and power
consumption.

TI also offers
the TMP117M digital temperature sensor, which supports requirements for medical
thermometers. For medical applications, the TMP117M provides ±0.1°C accuracy
from 30°C to 45°C, said TI, and supports American Society for Testing and
Materials (ASTM) E1112 and International Organization for Standardization (ISO)
80601 requirements for patient thermometers.

The TMP117 and
TMP117M target ultra-low-power patient monitoring, field transmitter, and
metering applications. The devices, which consume only 6.3 μW, are said to cut
power usage by up to 95% compared to a typical RTD measurement system, enabling
designers to meet tight power budgets in field transmitters and battery-powered
applications, said TI. In addition, the low power consumption reduces the
impact of self-heating, enabling more accurate temperature measurement. The sensors
are I2C- and SMBus-interface– compatible.

The TMP117M digital
temperature sensor for medical applications is available now in volume
quantities and is priced at $2.44 in quantities of 1,000. Pre-production
samples of the TMP117 are now available through the TI store and are priced at $1.60 in quantities of 1,000. Both
devices will be available in six-pin WSON no-lead packaging. An evaluation
board
(TMP117EVM) is available. Click here for the datasheet.