Freescale Semiconductor has introduced a family of inertia sensors that can improve performance, sensitivity, and reliability of next-gen airbag systems.
The sensor types MMA6222EG, MMA6255EG and MMA621010EG are based on Freescale's latest HARMEMS (High-aspect ratio MEMS) technology which has proved of value in airbag sensor applications. The sophisticated transducer design of these inertia sensors results in an improved offset behavior and, thanks to supercritical damping, in absolutely reliable action. This improves the system immunity against parasite RF oscillations with high amplitude. The conception of the devices inhibits faulty airbag activation through slamming doors or other irrelevant strong shocks.
The MMA62xxEG inertia sensors work on a 3.3 or 5 Volt supply voltage. Designers can use analog as well as digital outputs. In addition, the sensors support bi-directional self tests. The implementation of sophisticated monitoring functions is supported via the SPI bus.
The devices measure x and y axis with one single chip. They offer a digital 10-bit data output, measurement ranges up to 100g depending on the specific type. Other features are integrated low-pass options for signal preconditioning, integrated temperature sensor and voltage regulator and ratiometric voltage curve at the analog output.