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New 14-channel CDC for handheld electronics from ADI

Posted: 26 Dec 2005 ?? ?Print Version ?Bookmark and Share

Keywords:analog devices? cdc? ad7142? adi? capacitance-to-digital converter?

Analog Devices Inc. (ADI) introduced a programmable 14-channel capacitance-to-digital converter (CDC) for handheld consumer electronics that enables the design of contemporary touch controls that are paper-thin, yet highly reliable, to improve the user experience. The low power device AD7142 has the capability to automatically adjust to rapidly changing climatic conditions, making it suitable for mobile environments.

According to the press release, the AD7142 offers significant advantages over competing solutions, including higher immunity to environmental factors such as temperature and humidity that would degrade performance in other capacitance sensors. Additionally, the device's power consumption is said to be 50 percent lower than competing solutions, making it suitable for battery-powered applications. With 14 inputs, the AD7142 can be programmed for a variety of sensor configurations, such as finger-driven scroll bars, 8-way position sensors and scroll wheels that drive pop-up menus, making it easier to browse through large files of music, pictures and video, explained ADI.

"The user interface in cellular handsets and MP3 players presents one of the most challenging design environments, requiring the highest precision and functionality within the tightest space and power constraints of modern touch screen designs," said Pat O'Doherty, product line director, Precision Signal Processing at ADI. "Like our CDC products used in industrial and automotive applications, the AD7142 enables robust, error-free performance at a lower cost, while providing more design freedom than has been previously available."

The AD7142 includes adaptive threshold and sensitivity algorithms that allow the chip to adjust to the user's finger size, making the sensors robust for consumers with large and small fingers. The 16-bit, low noise, high accuracy CDC also allows the end-user to adjust individual sensor sensitivity levels to suit their style and touch.

Full power mode is less than 1mA, and shutdown current is less than 2?A. The device also offers the capability to flexibly trade-off output rate and power.

Offered in a choice of SPI or I?C compatible interfaces, the AD7142 is now available for sampling, with full production quantities expected in February 2006. The device is offered in a 32-lead 5-by-5mm lead frame chip scale package and operates from a 2.7V to 3.3V supply. This device is available in high volume production for $1.09. The AD7142 evaluation board is available for $199.

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