Bosch Sensortec's BMA220 Digital Sensor

ELECTRONICS:  The BMA220 digital sensor from Bosch Sensortec is the smallest digital acceleration sensor in LGA housing in the world ‒ it measures only 2 x 2 x 0.98 mm, including LGA housing. For the second time, Bosch Sensortec, the Bosch subsidiary specializing in sensors for consumer electronics, has emerged as the pace setter for technological innovation: In 2007, Bosch Sensortec was the first to successfully pack sensors in LGA housings measuring only three millimeters ‒ until then, the standard had been four millimeters. However, the unbroken trend towards miniaturization in mobile consumer electronics demands an even greater reduction in surface area: The new generation of 2 x 2 LGA housings occupies 79 percent less surface area on a circuit board than that required for the 6 x 6 sensor that marked Bosch Sensortec’s market debut in 2005.

The reduced dimensions are not linked to a loss in functionality or quality: The BMA220, which has already been delivered in large quantities to OEM customers, is a fully fledged, triaxial g-sensor with digital data output, four programmable measuring ranges from ±2 to ±16 g, and integrated evaluation electronics for recognizing specific motion patterns. For use in pedometers (step counters), Bosch Sensortec wrote specific evaluation algorithms tailored to the BMA220, a service that substantially shortened development time for the end device. Other applications include 3-D spatial orientation in mobile telephones, PDAs and game controllers, as well as targeted reactions to movements, such as the ability to mute a ring tone by tapping twice on the mobile phone.

The evaluation electronics integrated in the sensor obsoletes the need for intensive signal evaluation by the host application’s microcontroller. This greatly reduces energy use in the mobile device, which significantly extends battery life.

In the BMA220, the algorithms for motion recognition run internally on an ASIC; therefore, the sensor can autonomously and automatically distinguish between a random movement, a change in its spatial position, a single tap, double taps, and between slow and fast changes in movement.

The motion recognition parameters can be programmed by the customer. The sensor signals the availability of new data at the interrupt output; at the same time, the sensor also outputs them in conditioned form to the digital interface. This means that end product developers no longer have to grapple with complex raw three axis acceleration data from the internal micromechanical readings recorder.

- Edited by Liz Taurasi