STMicroelectronics - High-Accuracy Motion Sensor for Smarter Vehicle Electronics

The AIS226DS is a two-axis in-plane accelerometer capable of greater accuracy than is possible using two individual sensors. The device senses acceleration up to ±6g, where one ‘g’ is the acceleration due to gravity. As an example, 3g is the approximate acceleration experienced in a manned rocket during launch into space. The new AIS226DS can also resolve incredibly tiny angles of incline, smaller than 0.02 degrees. The ability to accurately measure incline is important in auto-leveling lamp, e-parking brake, and HSA (Hill Start Aid) applications.

Motion is sensed using a tiny MEMS motion detector built on a silicon chip. An interface chip, available with an SPI or I2C output, is also integrated, enabling direct connection to the vehicle’s Electronic Control Unit (ECU).

Other vehicle systems that can use the AIS226DS include event recorders for monitoring accidents or abusive driving, and GPS navigation systems using movement data for improved dead reckoning when the satellite signal is lost. There are also many non-automotive applications, such as vibration sensing in industrial equipment, black-box security monitors for shipping containers, inclinometers, and robotic systems.

The AIS226DS owes part of its high sensing accuracy to the low intrinsic noise of the electronic interface chip, which includes high-precision 16-bit analog-to-digital converters. The low noise allows usable converter resolution of 14 bits over a significant bandwidth, corresponding to a resolution of 0.25mg (on 2g full-scale). The sensor is also highly stable and maintains high accuracy (±70mg) throughout the automotive temperature range –40 to +105 degrees C, offering offset drift in the range of 0.2mg per degree C. The AIS226DS, assembled in a sturdy SO16W full-molded package, is qualified to the AEC-Q100 automotive quality standard.