Fermion: AHT20 Temperature and Humidity Sensor (Breakout)

The Fermion AHT20 is a high-precision, low-cost temperature and humidity sensor breakout from DFRobot. Built around an improved MEMS semiconductor capacitive humidity sensor element, it communicates over a standard I2C interface and operates across a wide 2–5 V supply range.

The sensor performs reliably across a wide temperature range of −40 °C to +85 °C, making it suitable for environmental monitoring, HVAC systems, weather stations, and data logging applications.

Key Features

• I2C Digital Output – Simple two-wire interface at address 0x38
• Wide Voltage Range – 2 V to 5 V DC supply
• High Precision – ±0.3 °C temperature accuracy, ±2% RH humidity accuracy
• Excellent Long-Term Stability – Low drift over time
• Quick Response – Strong anti-interference performance
• Compact Breakout – 30 mm × 20.5 mm board with standard 2.54 mm header

Specifications

• Operating Voltage: 2–5 V DC
• Interface: I2C (address 0x38)
• Board Dimensions: 30 mm × 20.5 mm (1.18″ × 0.81″)

Humidity (AHT20)

• Resolution: 0.024% RH
• Accuracy: ±2% RH
• Repeatability: ±0.1% RH
• Hysteresis: ±1% RH
• Response Time: 8 s
• Operating Range: 0–100% RH
• Long-Term Drift: <0.5% RH/year

Temperature (AHT20)

• Resolution: 0.01 °C
• Accuracy: ±0.3 °C
• Repeatability: ±0.1 °C
• Hysteresis: ±0.1 °C
• Response Time: 5–30 s
• Operating Range: −40 °C to +85 °C
• Long-Term Drift: <0.04 °C/year

Ideal For

• HVAC and climate control systems
• Weather stations and data loggers
• Dehumidifier and appliance monitoring
• Automotive environmental sensing

Package Contents

• 1× Fermion AHT20 Temperature and Humidity Sensor breakout
• 1× 2.54 mm 4-pin header

Resources

• Product Wiki
• 2D Dimensions (PDF)
• Circuit Diagram (PDF)