High accuracy digital temperature sensor

MMS Electronics improves temperature measurement accuracy without difficulty. The Smartec SMT172 is a complete digital ultra-low power, factory calibrated, high accuracy sensor with pulse width modulated output signal. PWM output sensors offer have high noise immunity and high reference accuracy. They are easy to interface and can easy be multiplexed. The duty cycle is proportional to the measured temperature. Inaccuracy is 0.1 ºC in the range of -10ºC to 100ºC and inaccuracy of 0.4ºC from -45ºC to -20ºC and 100ºC to 130ºC (max temp) with very low noise of 0.0001ºC. When adding a RC network the sensor can also be used as an analogue sensor. Designed for supply voltage 3V, 3.3V and 5V. The full voltage range is from 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 based on 1 measurement per second. Application are found in wearables, scientific, environmental, medical or industrial measurements.

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. A simple calculation returns the sensor temperature. 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 the factory calibrated SMT172 sensor.


The SMT172 is available in TO18, TO92, TO220, SOT223, SOIC, HEC and DIE packages. The SMT172-SOIC can be used for example on a PCB to protect nearby component from overheating. There are two probes, a slim 5mm probe that uses the SMT172-HEC sensor and a robust stainless steel probe SMT RVS1802 that uses the most accurate SMT172-18 sensor. Both probes come with a 5 meter shielded cable.  

For quick evaluation MMS Electronics has two boards with USB interface SMTAS04USBmini (max. 4 sensors) and SMTAS08USBmini (max. 8 sensors). For use with an I²C bus use the SMT172TOI2C board. This board also convert the SMT172 sensor output to replace the obsolete SMT160-30 sensor.

When adding a RC network the SMT172 temperature sensor can be used as an analogue sensor. The voltage can be measured and scaled with a programmable TFT panel and display the temperature. The panel meters are available in 3 sizes LA SGD-24 (2.4”), LA SGD-28 (2.8”) and LA SGD-35 (3.5”). For low power applications we recommend the sun-readable ePaper panel meter LA SGD21-B (2.1”). These panel meters are programmable and have two alarm outputs.

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

MMS Electronics Ltd is an authorised distributor for Smartec sensors, UFDC frequency sensors, Electronic Assembly Gmbh (Display Vision), Lascar Electronics Ltd, IcNexus display products and many other world class display and sensor manufacturers.

MMS Electronics Ltd
Tel 01943 877668

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