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Silicon Labs outs relative humidity sensor

Posted: 09 Nov 2012 ?? ?Print Version ?Bookmark and Share

Keywords:relative humidity sensor? Si7005? CMOS? mixed-signal IC?

Silicon Laboratories Inc. has unleashed a digital relative humidity (RH) and temperature "sensor-on-a-chip" solution. According to the company, the Si7005 sensor integrates a mixed-signal IC manufactured on standard CMOS with a proven technique of measuring humidity using a polymer dielectric film. In addition, the device targets applications that monitor or control humidity and temperature including automotive climate control and defogging, HVAC, refrigeration, weather stations, food processing, printers, asset tracking, and medical instruments such as nebulizers, oxygen concentrators and respiratory therapy equipment, indicated the company.

The Si7005 humidity sensor is a "plug-and-play," factory-calibrated RH and temperature sensing solution. The device's digital output and factory calibration frees the developer from having to calibrate the sensor and also makes Si7005 sensors completely interchangeable. No software/firmware update or recalibration effort is required to change from one sensing unit to another. The customer spends no time or labour on the manufacturing line adjusting each unit, which eases production, rework and field servicing. The Si7005 sensor's compact QFN package supports tape-and-reel packaging, automated pick-and-place PCB manufacturing and conventional soldering processes, further helping OEMs reduce manufacturing costs.

The Si7005 sensor uses modern sensing technologies to enable precise monolithic humidity and temperature sensing, stated Silicon Labs. Temperature is sensed by a precision bandgap referenced circuit on the die. Humidity is sensed by measuring the capacitance change of an industry-standard low-k dielectric layer applied to the surface of the die. Both temperature and humidity are precisely measured in very close proximity on the same monolithic device, providing exceptional measurement accuracy. The Si7005 device also consumes only 2?A on average at one measurement per minute, which makes it ideal for battery-powered applications.

The entire BOM for the Si7005 RH sensor solution is just two bypass capacitors versus the dozens of components often required to implement the same functionality with a discrete solution. The Si7005 device integrates sensing elements, an ADC, signal processing, non-volatile memory for calibration data and an I2C interface in a monolithic CMOS IC. This high level of single-chip integration makes the sensor rugged and reliable, reduces cost and development time, and simplifies board design, added the company.

Silicon Labs has also developed an innovative solution to address the vulnerabilities to damage and contamination encountered by traditional sensors. The Si7005 device is available with an optional, factory-installed, low-profile protective cover that protects the sensor from liquids and particulates before, during and after assembly, and throughout the end product's entire lifetime. This innovative filter eliminates material and labour costs associated with competing sensor solutions, and it has no impact on measurement sensitivity.

Volume production quantities of Silicon Labs' Si7005 humidity and temperature sensor are available in 4 x 4 mm QFN package. Product pricing for the Si7005 sensor in 10,000-unit quantities begins at $3.64.

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