Electronic Design

Miniature MEMS Accelerometer Adds Motion Sensing To Consumer Products

Through refined surface-micromachining technology, Analog Devices has packed the ADXL202E dual-axis integrated MEMS accelerometer into a tiny leadless chip-carrier (LCC) package. The technology also has improved the monolithic accelerometer's resolution, robustness, and stability over temperature while lowering its noise floor. The low-cost package has cut the the motion sensor's price tag as well.

Unlike previous-generation models, the ADXL202E implements a thicker MEMS structure to achieve robustness and lower the noise floor. It can survive a shock of 1000 g, while its noise floor has been reduced to 250 µg/(check)Hz. With this reduction, the accelerometer can resolve signals as low as 2.5 mg—yet it can still measure acceleration with a full-scale range of ±2 g. The improved process gives the device better stability, too. The drift over temperature is now only 2 mg/°C.

Combining these improvements with a low-cost miniature package, the supplier has opened the dual-axis accelerometer up to new applications. The ADXL202E will bring motion-sensing capabilities to consumer products like disk drives, laptops, and electronic games. PDAs and cell phones will have fewer buttons. Instead, they'll rely on speech and gesture recognition. Researchers are even investigating tilting and motion inputs for these appliances. Such accelerometers will let disk-drive makers relentlessly pursue higher storage densities by minimizing vibrations. They'll also increase a laptop's security by sounding an alarm when it leaves a secure perimeter. In fact, SmartMoves of Cambridge, Mass., is developing such a security system.

Integrating signal-conditioning circuitry with a microscopic MEMS structure on a single chip, the ADXL202E provides a duty-cycle output that is proportional to acceleration. It uses a single 2.7- to 5.2-V supply for operation, and it consumes less than 250 µA per axis. It comes in an 8-pin LCC that measures 5 by 5 by 2 mm. In 100,000-piece batches, it costs $4.99 each.

Analog Devices Inc., 831 Woburn St., Wilmington, MA 01887; (781) 937-1428; www.analog.com.

See associated figure

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.