GY-21 HTU21 Humidity & Temperature Sensor Module

Industrial High Precision GY21 Si7021 Humidity Sensor with I2C Interface Arduino
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GY-21 HTU21 Humidity & Temperature Sensor Module Specification

The Si7021 I2C Humidity and Temperature Sensor is a monolithic CMOS IC integrating humidity and temperature sensor elements, an analog-to-digital
converter, signal processing, calibration data, and an I2C Interface.
The patented use of industry-standard, low-K polymeric dielectrics for sensing humidity enables the construction of low-power, monolithic CMOS Sensor ICs with low drift and hysteresis, and excellent long term stability.
The humidity and temperature sensors are factory-calibrated and the calibration data is stored in the on-chip non-volatile memory. This ensures that the sensors are fully interchangeable, with no recalibration or software changes required.
The Si7021 is available in a 3x3 mm DFN package and is reflow solderable.
It can be used as a hardware- and software-compatible drop-in upgrade for existing Featuring precision sensing over a wider range and lower power consumption.
The Si7021 offers an accurate, low-power, factory-calibrated digital solution ideal for measuring humidity, dew-point, and temperature, in applications ranging from HVAC/R and asset tracking to industrial and consumer platforms.


Power supply : 3-5V
Relative humidity: ± 3% RH (max), 0-80% RH
Temperature: ±0.4°C (max), -10 to 85°C
Operating range: 0 to 100% RH
Operating range: Up to -40°C to +125 °C
Wide operating voltage: 1.9V - 3.6V
Low power consumption: 150 ?A active current
Standby current: 60 nA
Size: 1.3*1cm/0.51*0.39"


Respiratory therapy
White goods
Indoor weather stations
Micro-environments/data centers
Automotive climate control and defogging
Asset and goods tracking
Mobile phones and tablets

  • HTU21D is a low-cost, easy to use, highly accurate, digital humidity and temperature sensor.
  • This sensor is ideal for environmental sensing and data logging and perfect for a weather stations for humidity control systems.
  • All you need is two lines for I2C communication and you'll have relative humidity readings and very accurate temperature readings as a bonus!