New SD746 features wake-up on motion function

GRAZ, AUSTRIA: SensorDynamics, a producer of multidimensional inertial and wireless sensors announced the new and improved version of SD746, a micromechanical combo sensor. The combo sensor measures angular rate and acceleration along all three axes and comes in a tiny QFN 40 package. The SD746 provides temperature-compensated and factory calibrated digital measurement values with high resolution via I²C or SPI interface plus wide measurement ranges (±2048°/s and ±8g).

For battery powered applications, like the air-mouse, it is essential that the system switches to sleep mode as soon as no more motion is detected. In order to efficiently resume operations after sleep mode, a low- power motion detection function is needed. The new SD746 features a low-power motion detection function where power consumption is drastically reduced by turning off the gyroscopes and operating the accelerometers in a pulsed mode. Equipped with this new feature, the SD746 is the ideal motion sensor for air-mouse, gaming remote control and other handheld applications.

Sensor properties
As opposed to the normal operation mode where power consumption is in the mA range, the new motion detection mode reduces power consumption to 25µA at 1Hz accelerometer sample rate. Through the digital interface the user can set a physical g-level which serves as a detection threshold.

If the variation of the acceleration detected on the three accelerometers is greater than the threshold set, an ‘interrupt pin’ is activated. This interruption can be used to wakeup the host controller, which in turn brings back the sensor to the normal operation mode. If the power consumption on a higher sleep mode is acceptable, the user can opt for faster accelerometer sampling rates of up to 8 sampling windows per second, with a power consumption of 125µA.

The new SD746 is scaled for an operating voltage of 2.55 through 3.6 V and an operating temperature range of -40 to +85°C. The offset error at room temperature is ±5°/s for the gyroscope signal and ±0.05g for the accelerometer signal. Sensitivity error at room temperature is ±2% for the gyroscope and acceleration signal, respectively.