Si7015-A10
12 Rev. 1.0
4. Functional Description
Figure 5. Si7015 Functional Block Diagram
4.1. Overview
The Si7015 is a digital relative humidity and temperature sensor. This monolithic CMOS IC integrates temperature
and humidity sensor elements, an analog-to-digital converter, signal processing, calibration data, and an I
2
C host
interface. Both the temperature and humidity sensors on each unit 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.
While the Si7015 is largely a conventional mixed-signal CMOS integrated circuit, relative humidity sensors in
general and those based on capacitive sensing using polymeric dielectric have unique application and use
requirements that are not common to conventional (non-sensor) ICs. Chief among those are:
The need to protect the sensor during board assembly, i.e., solder reflow, and the need to subsequently
rehydrate the sensor.
The need to apply temperature correction to the humidity readings.
The need to protect the sensor from damage or contamination during the product life-cycle.
The impact of prolonged exposure to extremes of temperature and/or humidity and their potential effect on
sensor accuracy.
The effects of humidity sensor “memory”.
Each of these items is discussed in more detail in the following sections.
