Measuring only 2.2x2.2mm2 and drawing as little as 190 µA, the BMC150 combines a 3-axis geomagnetic sensor and a state-of-the-art 3-axis accelerometer in a single package. The chip reduces the number of components that otherwise have to be handled and qualified separately. Both sensors form a logical and functional unit, since the g-vector generated by the accelerometer is required to calculate the tilt compensation for the azimuth data produced by the geomagnetic sensor. The accelerometer and the geomagnetic sensor in BMC150, however, can also be used as two fully functional independent devices.
The wide measurement range of +/- 1300 µT per axis makes it more tolerant to stray magnetic fields associated to loudspeakers or other magnetic components in smartphones. On the other hand, it’s very low noise of just 0.3 µT enables very accurate measurement. With the eCompass library V3.0, Bosch Sensortec also offers data fusion software that performs the calculations for tilt compensation and thus generates precise heading information for compass applications. The integrated smart interrupt engine enables the sensor module to automatically identify motion patterns and situations. For instance, it detects free fall conditions, flat orientation on a table, tap sensing or even no motion at all for a definable period of time.
These status data enable the implementation of many innovative features for mobile devices such as activating sleep mode and waking it up by tapping it with a finger. Developers also benefit from the new FIFO buffer which acts as a temporary storage for measurement data until they are needed. This feature offloads the application processor further, effectively reducing the system's overall power consumption. The accelerometer section of the sensor can be adjusted to four different g ranges between +/- 2g and +/- 16g, enabling designers to select the g range that fits best their application.
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