Apple Likely Equipped the iPhone 6 With Two Accelerometers to Minimize Power Consumption

Recent iPhone 6 teardowns reveal that the iPhone 6 features two accelerometers, a six-axis InvenSense combination gyroscope-accelerometer and a Bosch BMA280 three-axis accelerometer. The big question has been why Apple would need two accelerometers in the new iPhone. After some analysis Chipworks believes the answer is power management.

The InvenSense device can operate as a six axis inertial sensor, or as either a three-axis gyroscope or a three-axis accelerometer. It is rated to consume 3.4 mA in the six-axis mode, 3.2 mA in the gyroscope mode and 450 µA in the accelerometer normal mode. By contrast, the Bosch device operates as a 3-axis accelerometer only and it consumes 130 µA of current in the accelerometer normal mode. Both devices offer two low power levels of operation for the accelerometer function. The InvenSense device actually consumes less current in its lowest power mode, with a 1 Hz update rate.

The InvenSense can provide full six-axis integration of the data by the on-chip digital motion processor which is great for gaming and other applications that need sophisticated inertial sensing capabilities and higher sensitivity.


However, the Bosch device operates at lower power and has much faster start up time. This makes it good for situations where full six-axis integration is not required and where lower sensitivity is acceptable, for example for purposes such as screen orientation and pedometer functionality.

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