AHT21 High Precision I2C Digital Temperature and Humidity Sensor Module

AHT21 High Precision I2C Digital Temperature and Humidity Sensor Module provides highly accurate and reliable environmental monitoring for demanding applications. This sophisticated sensor integrates calibrated temperature and humidity sensing elements, delivering fully compensated digital outputs via a simple I²C interface. Therefore, you can easily integrate the AHT21 into any microcontroller-based project, eliminating the need for complex analog circuitry or calibration. Its outstanding long-term stability and fast response time make it a superior choice for professional climate control, weather stations, and data logging systems. Furthermore, its small size and low power consumption significantly benefit portable and battery-operated devices.

Key Features:

• High Accuracy: Delivers precise measurements with a typical humidity accuracy of ±2% RH and a temperature accuracy of ±0.3°C.
• Calibrated Digital Output: The sensor provides direct, factory-calibrated digital signals, simplifying implementation and ensuring measurement reliability without user calibration.
• I²C Communication: Uses the standard two-wire I²C protocol, making it compatible with nearly all popular microcontrollers, including Arduino, ESP32, and Raspberry Pi.
• Fast Response Time: Features quick thermal and moisture response, enabling real-time environmental condition monitoring.
• Wide Operating Range: Operates reliably across a broad temperature range from −40°C to +80°C.

Technical Specifications:

• Supply Voltage (V_DD): 2.0 V to 5.5 V DC (Wide input range)
• Humidity Range: 0% RH to 100% RH
• Humidity Accuracy: ±2% RH (Typical)
• Temperature Range: −40°C to +80°C
• Temperature Accuracy: ±0.3°C (Typical)
• Resolution: 0.024% RH and 0.016°C
• Interface: I²C (Two-Wire Serial Interface)
• Current Consumption: ≈ 0.9 mA (Measuring mode)

Mechanical Specifications:

• Sensor IC: AHT21 (Aosong/Asair)
• Module Output: 4-pin header (VCC, GND, SDA, SCL)
• Housing: Robust plastic casing protects the sensing element from physical contact and contamination.
• Protection: Offers high resistance to dust and condensation compared to open sensors.

Dimensions:

• Module Board Size: ≈ 16 mm x 11 mm
• Mounting Hole Diameter: Standard ≈ 2 mm
• Pin Pitch: 2.54 mm (Standard for breadboards and custom PCBs)
• Weight: < 1 g (Extremely light)

Pinout and Wiring:

• VCC: Connect to the 3.3 V or 5 V power supply voltage.
• GND: Connect to the circuit ground reference (0 V).
• SDA (Serial Data): I²C Data line. Connect to the host microcontroller’s SDA pin. Note, this line typically requires a pull-up resistor to VCC.
• SCL (Serial Clock): I²C Clock line. Connect to the host microcontroller’s SCL pin. Similarly, this line also requires a pull-up resistor to VCC.

Datasheet Reference:

• Download AHT21 Temperature and Humidity Sensor Datasheet

Commonly Used in:

• HVAC and Climate Control Systems: Providing accurate feedback for regulating temperature and humidity in residential and commercial buildings.
• Weather Stations: Used in amateur and professional weather instruments to gather reliable atmospheric data.
• Data Loggers: Integrated into portable logging devices to record environmental conditions over time.

Applications:

• Indoor Air Quality (IAQ) Monitoring: Assessing comfort levels and health parameters in enclosed spaces.
• Greenhouse and Terrarium Control: Automating irrigation and ventilation based on real-time environmental metrics.
• Medical Devices: Monitoring humidity and temperature in respiratory equipment and incubators.
• Server Room Monitoring: Alerting administrators to conditions that could damage sensitive IT equipment.

Equivalent Models:

• SHT20 / SHT30 (Sensirion): Highly regarded I²C temperature and humidity sensors that offer comparable or slightly better accuracy, often used as professional alternatives.
• DHT22 (Aosong): An older, lower-cost, and lower-resolution sensor that utilizes a proprietary one-wire protocol, however, it is not a direct drop-in replacement.
• HTU21D (TE Connectivity): A functionally similar high-precision I²C sensor, providing a competitive alternative for new designs.

Package Includes:

• 1 x AHT21 High Precision I2C Digital Temperature and Humidity Sensor Module