Infineon — XENSIV PAS CO2 Carbon Dioxide Sensor

The XENSIV™ PAS CO2 from Infineon is an exceptionally small carbon dioxide (CO₂) sensor which uses photo-acoustic spectroscopy (PAS) to accurately measure the concentration of real CO₂ in the environment. The PAS CO2 measures just 14 mm x 13.8 mm x 7.5 mm and is highly accurate, providing readings accurate to within ±30 ppm + 3%.

The device uses a highly sensitive MEMS microphone to detect the pressure changes created by CO₂ molecules shaking as a result of being exposed to infrared light in the sensor cavity. The integrated microcontroller then calculates a measurement of the concentration of CO₂.

The XENSIV™ PAS CO2 integrates a PAS transducer, which consists of an infrared emitter, an optical filter tuned to the CO₂ wavelength, and the MEMS microphone, as well as a microcontroller for signal processing and running algorithms, and a MOSFET chip to drive the infrared source.

The PAS CO2 is a plug-and-play device which offers various configuration options, including automatic baseline offset calibration, pressure compensation, and signal alarm. The sensor also provides sample rate and early measurement notifications, which can be used to manage power consumption. Interface options include I2C, UART, and PWM.

Typical power consumption of the device is 30 mW when taking one measurement a minute. The emitter requires a supply voltage of 12 V and the remaining components require 3.3 V.

The PAS CO2 is supplied in a surface-mount package, allowing for cost-effective and high-volume manufacturing.