Low power digital temperature sensors

MMS Electronics has available the Smartec SMT172 temperature sensor and evaluation boards. The SMT172 is a 3 pin, complete digital ultra-low power, fully calibrated, high accuracy sensor with pulse width modulated output signal. The duty cycle is proportional to the measured temperature. Accuracy is less than 0.1 ºC in the range of -10ºC to 100ºC and accuracy of 0.4ºC from -45ºC to -20ºC and 100ºC to 135ºC (max temp) with very low noise of 0.0001ºC.

Supply voltage 3V, 3.3V and 5V. Full voltage range is 2.7 V to 5.5 V.  This is the most energy efficient temperature sensor in the world with an average current of < 60uA or 220nA (1 measurement / second).

How is it done :

The SMT172 is designed using the most recent advances in silicon temperature sensing technology, the SMT172 has applied sophisticated IC design techniques and high-precision calibration methods. The sensor has a pulse width modulated PWM output signal, where the duty cycle is proportional to the measured temperature value. This makes it possible for the sensor to interface directly to a microprocessor without using an Analogue to Digital converter. It is an extremely easy way to measure the temperature with SMT172 factory calibrated sensor.

The frequency of the output sensor is fixed and only the duty cycle contains the temperature information. A simple calculation returns the sensor temperature.

Using frequency output sensor have many advantages over analogue sensors. Frequency output sensors offer have high noise immunity and high reference accuracy. They are also easy to interface and can easy be multiplexed.

The SMT172 is available in TO18, TO92, TO220, SOT223, SOIC, HEC and DIE packages. There is also a robust stainless steel probe that uses the most accurate sensor supplied with a 5 meter cable SMT RVS1802.

Evaluation boards SMTAS04USBmin (max. 4 sensors) and SMTAS08USBmini (max. 8 sensors) are available for quick evaluation. The sensors are powered from the mini USB port. Temperature can be read using a terminal program or displayed in graph with the Smartec software.

For use with an I²C bus MMS Electronics has an adaptor available SMT172TOI2C to connect the temperature sensor SMT172 to the I²C bus.

MMS Electronics has demo code for the SMT172 sensor for use with an Arduino board.  Arduino compatible display shields with 1×8, 2×16, 3×16 alphanumeric display or 128×64 graphic displays are also available. Developers have access to the documentation that is required to connect the SMT172 or EA DOG displays to the Arduino.


Low power applications such as wearable electronics, wireless sensor networks, wireless temperature monitoring and body temperature measurement. Medical applications, bio-chemical analysis, precision equipment, indoor and outdoor environmental monitoring. Process control, battery charging, consumer goods, electronic circuit protection, temperature monitoring in notebook and desktop computers.

Please contact MMS Electronics Ltd with your sensor or display enquiries.

MMS Electronics Ltd is an authorised distributor for Smartec sensors, Excelera frequency transducers, Electronic Assembly Gmbh (Display Vision) and IcNexus display products.

MMS Electronics Ltd


Tel 01943 877668

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