DHT22 temperature-humidity sensor




ABOUT DHT22
(Digital Temperature and Humidity Sensor Module)

The DHT22 is a  digital temperature and humidity sensor. It uses to measure humidity and temperature by using a thermistor.
Small size & low consumption & long transmission distance(20m) enable DHT22 to be suited in all kinds of harsh application occasions.

TECHNICAL specification

  • 3 to 5V power supply and I/O
  • 2.5mA max current 
  • Good for 0-100% humidity readings with 2-5% accuracy
  • Good for -40 to 80°C temperature readings ±0.5°C accuracy
  • No more than 0.5 Hz sampling rate (once every 2 seconds)
  • Body size 27mm x 59mm x 13.5mm (1.05" x 2.32" x 0.53")
  • 4 pins, 0.1" spacing
  • Weight  2.4g
Pin sequence number: 1 2 3 4 (from left to right direction)
1.PIN NO-1 VDD POWER SUPPLY
2.PIN NO-2  DATA SIGNAL
3.PIN NO-3 NULL
4.PIN NO 4 GROUND

Temperature Measuring Component
  • To measure temperature this sensor uses a Thermistor.
  • A thermistor is a variable resistor that changes its resistance with a change of temperature. These sensors are made by sintering of semiconductive materials, such as ceramic or polymers in order to the large change in a resistor with small changes in temperature. As temperature changes, there is a change in the value of resistance by which we measure the temperature of our environment.


APPLICATION OF DHT22

  • It is used for temperature and humidity measurement.
  • It is used as a weather station to measure temperature and humidity in the air.
  •  It is an automatic climate control sensor.
  • It is also used as an environmental monitoring device.
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