Si7005 Humidity Readings
The Si7005 humidity and temperature sensor is rated at ±3% typical, ±4.5% max relative humidity accuracy and ±0.5 °C temperature accuracy. It is one of the lowest power humidity sensors available, making it ideal for battery-powered applications, consuming only 240 µA during a relative humidity measurement. The device operates by allowing air to come into contact with an exposed polyimide sensor through an opening in the packaging, shown here. Moisture in the air causes a capacitance change to occur in the polyimide sensor and the on-chip signal conditioning converts this capacitance to a humidity reading, made available to the user over the I2
Plug-n-play Solution - No Manual Calibration Needed
The Si7005 humidity and temperature sensor requires few external components – only 2 surface mount capacitors, much less than traditional discrete resistive or capacitive sensor circuits. This highly integrated device reduces the amount of board space, complexity and cost required for a relative humidity and temperature sensor solution. The Si7005 humidity and temperature sensor is a “Plug-and-play” solution compared to the lengthy discrete design engineering effort and manual calibration required by discrete humidity sensing solutions. Some humidity sensors and modules may require customers to perform a per-device calibration during manufacturing. Silicon Labs calibrates each Si7005 humidity and temperature sensor and stores the calibration data in the device’s non-volatile flash memory. No external calibration circuitry is required, simplifying designs and reducing end system manufacturing costs.
Alternative Protective Filters
Most humidity sensors require protection from contaminants onto the exposed sensor. Some existing devices require placing protective tape over the package cavity for protection during board assembly and subsequent removal, and addition of a plastic filter cover after assembly to protect the device during field use. These additional components and steps are costly and inconvenient for manufacturers to implement, but are unnecessary with the Si7005 humidity and temperature sensor.
Si7005 Humidity and Temperature Sensor Pre-Installed Protective Filter
Silicon Labs offers the Si7005 humidity and temperature sensor with a thin hydrophobic filter/cover pre-installed, to protect the exposed sensor. The protective filter/cover provides protection during board assembly, eliminating the cost and inconvenience of adding and removing tape on the device. It should be left on the product eliminating the need to add any post-assembly protective covers. Air passes through the filter cover, while particles are filtered out.
Si7005 Humidity and Temperature Sensor Example Source Code and Drivers
Example demo source code, Linux and Android drivers are also available.
Si7005 Driver Code
*The Android robot is reproduced or modified from work created and shared by Google and used according to terms described in the Creative Commons 3.0 Attribution License.