5.4 Si7021 Relative Humidity and Temperature Sensor
The Si7021 I
2
C 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 I
2
C 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 I
2
C bus used for the Si7021 is shared with the EXP header. The temperature sensor is normally isolated from the I
2
C line. To use
the sensor, SENSOR_ENABLE (PD15) must be set high. When enabled, the sensor's current consumption is included in the AEM
measurements.
SENSOR_ENABLE
Si7021
Temperature
& Humidity
Sensor
0: I2C lines are isolated, sensor is not powered
1: Sensor is powered and connected
PC11 (I2C0_SCL #15)
PC10 (I2C0_SDA #15)
PD15
SENSOR_I2C_SDA
SENSOR_I2C_SCL
VMCU
VDD
SCL
SDA
BGM13P
Figure 5.4. Si7021 Relative Humidity and Temperature Sensor
Refer to the Silicon Labs web pages for more information:
http://www.silabs.com/humidity-sensors
UG338: BGM13P22 Blue Gecko Module Radio Board User's Guide
Peripherals
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