CN0395,Volatile Organic Compound Detector for Indoor Air Quality Measurement
Created: Sep 18, 2018
The circuit is optimized for the Figaro TGS8100 sensor, which is comprised of a MOS sensing chip and an integrated heater formed on a silicon substrate using MEMS technology. Other MOS sensors can be used by making appropriate changes in the hardware and software.
The circuit uses a 12-bit, current output digital-to-analog converter (DAC) for precision control of the heater current, and the flexible software allows the heater to operate in one of the following four modes: constant current, constant voltage, constant resistance, and constant temperature.
The circuit is able measure a wide range of sense resistance values by using a software-selectable, five range resistor divider. The board also includes a temperature and humidity sensor that is used for compensating the gas concentration value.