Si7007-A20

Rev. 1.2

11

4. Functional Description

Figure 5. Si7007 Block Diagram

The Si7007 is a digital relative humidity and temperature sensor that integrates temperature and humidity sensor

elements, an analog-to-digital converter, signal processing, calibration, polynomial non-linearity correction, and a

PWM output all in a single chip. The Si7007 is individually factory-calibrated for both temperature and humidity,

with the calibration data stored in on-chip, non-volatile memory. This ensures that the sensor is fully

interchangeable, with no recalibration or changes to software required. Patented use of industry-standard CMOS

and low-K dielectrics as a sensor enables the Si7007 to achieve excellent long term stability and immunity to

contaminants with low drift and hysteresis. The Si7007 offers a low power, high accuracy, calibrated and stable

solution ideal for a wide range of temperature, humidity, and dew-point applications including medical and

instrumentation, high reliability automotive and industrial systems, and cost-sensitive consumer electronics.

While the Si7007 is largely a conventional mixed-signal CMOS integrated circuit, relative humidity sensors in

general and those based on capacitive sensing using polymeric dielectrics 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 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.