6.2 Si7021 Relative Humidity and Temperature Sensor
The Si7021 I2C relative humidity and temperature sensor is a monolithic CMOS IC integrating humidity and temperature sensor ele-
ments, 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 RH/ temperature sensors in 3x3 mm DFN-6 packages, featuring precision sensing over a wider range and
lower power consumption. The optional factory-installed cover offers a low profile, convenient means of protecting the sensor during
assembly (e.g., reflow soldering) and throughout the life of the product, excluding liquids (hydrophobic/oleophobic) and particulates.
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.
The I2C bus used for the Si7021 is shared with the Expansion Header. The temperature sensor is normally isolated from the I2C line.
To use the sensor, SENSOR_ENABLE (SENSOR_ENABLE (tied high)) must be set high. When enabled, the sensor's current con-
sumption is included in the AEM measurements.
SENSOR_ENABLE
0: I2C lines are isolated, sensor is not powered
1: Sensor is powered and connected
PC11 (I2C0_SCL)
PC10 (I2C0_SDA)
(tied high)
SENSOR_I2C_SDA
SENSOR_I2C_SCL
VMCU
VDD
SCL
SDA
Temperature
& Humidity
Sensor
BGM113
Si7021
Figure 6.2 Si7021 Relative Humidity and Temperature Sensor
UG187: Blue Gecko Wireless Starter Kit with BGM113 Module
Peripherals
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