Temperature/Humidity Sensor Module Breakout - HTU21D

This module features the HTU21D, a combined humidity and temperature sensor. The sensor itself operates at 3V. The back of the module contains a 3.3V regulator and level-shifting MOSFET transistors to make the module compatible with both 3.3V and 5V MCUs. This makes it well suited for use with, among others, Arduino and Esp32.

Due to the small size of the module, it can be mounted in almost anything for monitoring or controlling humidity and/or temperature, such as thermostats, hygrostats, indoor weather stations, and similar devices.

MAIN FEATURES:

• Reports humidity over a range of 0% to 100% RH
• Humidity measurement accuracy is ±2% above 5 to 95% RH (typ)
• Reports temperature within a range of -40 to 125 °C
• The accuracy of the temperature reading is ±0.6°C over a range of -30°C to 90°C (typ)
• Fast <50mS read time
• Uses I2C interface
• 3.3 and 5V logic compatible

The HTU21D sensor is capable of measuring humidity over the full range of 0 to 100% RH with a typical accuracy of ±2% over the range of 5 to 95% with a maximum of ±5% at the ends of the range. The humidity measurement has a standard 12-bit resolution.

The device's maximum temperature range is -40 to 125 °C. The HTU21D temperature sensor has a typical accuracy of ±0.4°C over the range of 0 to 70°C with a maximum of ±1°C above -30 to 90°C and a maximum of ±1.6°C at the ends of the range from -40 to 125 °C. The temperature measurement has a standard 14-bit resolution.

The sensor has a small window for air to make contact with the sensor. Keep contaminants away from this window, as this can affect the accuracy of the humidity measurement. The window must remain open to air, but it can be protected against dust and similar contaminants with a PTFE membrane, mesh, or other material that still allows air to pass through, or by placing it in a space where air passes through but is protected from excessive dust or moisture.

If you solder on the board, it is safest not to use fluids to clean the board, although it can be done if care is taken to ensure the cleaning solution does not enter the sensor window.

Module Connections

The module has a 4-pin header on the assembly.

• VIN = Connect to 3.3V or 5V to match MCU.

• GND = Connect to system ground. This ground must be common with the MCU.

• SCL = I2C Clock / SCL – Connects to SCL on MCU

• SDA = I2C Data / SDA – Connects to SDA on MCU

TECHNICAL SPECIFICATIONS:

• Vcc range 3.3 to 5.5 V
• Vmax <200uA
• Tmin Minimum sampling period 50mS
• Humidity Max. range 0% to 100% RH (± 5% RH)
• Optimal range 5% to 95% RH (± 2% RH typ)
• Temperature Max. range -40 to 125 °C (±1.6 °C)
• Optimal range -30 to 90°C (±0.6°C typ)
• Dimensions L x W (PCB) 13.5 x 10.5 mm (0.53 x 0.42″)