Winsen MH-Z19C NDIR CO2 Sensor HVAC/IAQ - UART/PWM Output

The MH-Z19C requires a stable 5.0V DC power supply with a tolerance of ±0.1V. It is critical to provide clean, regulated power within this range to ensure accurate sensor readings and long-term reliability.

The module provides two output options: a 3.3V TTL UART serial interface and a PWM signal. For UART communication, connect the sensor's TX/RX pins to your microcontroller's UART pins (logic level 3.3V). The PWM output provides a duty cycle proportional to the CO2 concentration.

The sensor detects CO2 concentrations from 400 ppm (ambient air) up to 10,000 ppm. It uses NDIR technology, which offers good selectivity and stability. Accuracy is maintained through built-in temperature compensation, though specific tolerance figures should be confirmed from the latest Winsen datasheet.

The MH-Z19C is typically pre-calibrated. However, for critical applications, a manual calibration procedure using a known CO2 concentration (e.g., fresh air at 400 ppm) can be performed via UART commands to maintain optimal accuracy over its extended lifespan.

The gold-plated infrared chamber acts as a highly reflective surface for the NDIR optical path. This maximizes the infrared light signal reaching the detector, improving signal-to-noise ratio and overall measurement consistency and sensitivity.