DHT22/AM2302 Digital Temperature & Humidity Sensor (Original Offical)

Description

The DHT22 / AM2302 is a high-performance digital temperature and humidity sensor from ASAIR (Aosong), designed as the upgraded successor to the widely used DHT11. It combines a capacitive humidity sensing element with an NTC thermistor and an integrated 8-bit microcontroller, delivering fully calibrated digital output over a simple single-wire interface .

The sensor provides significantly improved accuracy and range compared to the DHT11. Humidity measurement spans 0% to 100% RH with ±2% RH accuracy (at 25°C, 50% RH), while temperature measurement covers -40°C to +80°C with ±0.5°C accuracy . Resolution is 0.1°C and 0.1% RH, enabling precise environmental tracking . The sensor operates from 3.3V to 5.5V DC, drawing an average of 0.5mA during measurement and entering a 100µA standby mode between readings .

Each DHT22 is individually calibrated in a precision humidity chamber, with calibration coefficients permanently stored in on-chip OTP memory . This factory calibration eliminates the need for external trimming and ensures full interchangeability between units . The sensor also features excellent long-term stability, with specified drift of less than 0.5% RH per year .

Important Note: The DHT22 is a digital sensor, not an analog one. It requires a minimum 2-second interval between readings — querying it more frequently will return errors or stale data . A pull-up resistor (typically 5.1kΩ–10kΩ) on the data line is required for reliable communication; many module versions include this onboard, but bare sensors require an external resistor . The sensor is not waterproof and should be kept dry; for outdoor use, a protective ventilated enclosure is recommended . Readings may fail as NaN in Arduino code if wiring is loose or timing is incorrect — always implement error checking .

Whether you are building a weather station, a greenhouse controller, or a smart home environmental monitor, the DHT22 provides reliable, calibrated digital sensing with superior accuracy and range compared to the DHT11.

Features

• Original ASAIR AM2302 chip — Genuine quality with factory full-range calibration

• High accuracy — ±2% RH and ±0.5°C, significantly better than DHT11

• Wide measurement range — 0–100% RH and -40°C to +80°C

• Single-wire digital interface — Only one data pin required, plus power and ground

• Factory-calibrated — Calibration coefficients stored in OTP memory; no external trimming

• Full interchangeability — Units are interchangeable without recalibration

• Low power consumption — ~0.5mA measuring, ~100µA standby

• Long-term stability — Specified drift ≤0.5% RH/year

• 4-pin package — Standard 0.1″ spacing, breadboard and PCB compatible

• Wide application range — Weather stations, HVAC, agriculture, industrial control, home automation

Technical Specifications