Datasheet STC31 CO Sensor Based on Thermal Conductivity 2 Calibrated gas concentration and temperature output Next level repeatability and long term stability Compensates for Relative Humidity with additional SHTxx sensor Product Summary The STC3x sensor family is Sensirions series of Gas Concentration sensors designed for high-volume applications. The STC3x utilizes a revolutionized thermal conductivity measurement principle, which results in superior repeatability and long-term stability. This make the STC31 a perfect choice for applications where reliability is key. 2 The sensor features a digital I C interface, which makes it easy to connect directly to a microprocessor. The outstanding performance of these sensors is based on Sensirions patented CMOSens sensor technology, which combines the sensor element, signal processing and digital calibration on a small CMOS chip. The well-proven CMOS technology is perfectly suited for high-quality mass production and is the ideal choice for demanding and cost-sensitive OEM applications. Benefits of Sensirions CMOSens Technology High reliability and long-term stability Best signal-to-noise ratio Industry-proven technology with a track record of more than 15 years Designed for mass production High process capability Content 1. Sensor Performance .............................................................. 2 2. Specifications ......................................................................... 3 3. Digital Interface Description ................................................... 4 4. Physical specifications ......................................................... 12 5. Sensor Integration ................................................................ 14 6. Shipping Package ................................................................ 15 7. Ordering Information ............................................................ 15 Important Notices ......................................................................... 16 Headquarters and Subsidiaries .................................................... 16 www.sensirion.com Confidential D1 Version 1.1 October 2020 1/16 1. Sensor Performance 1 1.1 Concentration Parameter Value 2 3 Calibrated for CO in N and CO in air 2 2 2 4 Measurement range 0 to 25 vol% 0 to 100 vol% 5 Accuracy 0.5 vol% + 3% measured value 1 vol% + 3% measured value Repeatability 0.2 vol% 6 Temperature stability 0.025 vol% / C Resolution 16 bit 7 1.2 Temperature Parameter Value Measurement range -20 C to 85 C Resolution 16 bit Accuracy 0.5 C (10 C to 50 C) 1.5 C (-20 C to 85 C) Repeatability 0.1C 1 Valid at temperature at which ASC or FRC is performed and humidity = 0-95% RH, <50C dew point, pressure = 800-1200mbar, Vdd=3.3V. 2 Specifications are only valid for these binary gas mixtures (air is interpreted as being one type of gas). 3 Air is defined as 78.1% nitrogen, 21.0% oxygen and 0.9% argon. 4 Measurement range can be chosen by setting the gas model as described in 3.3.2 5 Accuracy is defined after performing FRC at 0 vol%.providing a correct temperature, humidity and pressure measurement. Consult sections 3.3.3, 3.3.4, 3.3.5 and 5 for detailed information. 6 Slope of CO2 accuracy when changing temperature. Fulfilled by 90% of sensors after calibration 7 The measured temperature is the temperature of the bulk silicon in the sensor. This temperature value is not only depending on the gas temperature, but also on the sensors surroundings. See section 5.2 for more details. www.sensirion.com Confidential D1 Version 1.1 October 2020 2/16