ADI ADXL345 Integrated Micro-electro-mechanical System Accelerometer

The ADXL345, from Analog Devices, is a three-axis digital iMEMS (integrated micro-electro-mechanical system) accelerometer. The motion sensing device is designed for energy-constrained portable consumer products. The ADXL345 accelerometer is the lowest-power device in its class, achieving an 80%power savings compared to competing three-axis inertial sensors. The ADXL345 also features an on-chip ADC (analog-to-digital converter) that simplifies hardware configurations in wireless handsets, personal navigation devices, and other mobile applications. The ADXL345 three-axis iMEMS digital accelerometer is available today in pre-production quantities with volume production scheduled for March 2009. The ADXL345 comes in a small, thin 14-lead LFCSP and is priced at $3.04 in 1,000-unit quantities.

Analog Devices ADXL345 Small, Ultra Low Power, 3-Axis, ±2/4/8/16g Digital Accelerometer

ADXL345 Features

  • Ultra low power: 25 to 130 µA at Vs=2.5V (typ)
  • Power consumption scales automatically with bandwidth
  • User selectable fixed 10-bit resolution or 4mg/LSB scale
  • factor in all g-ranges, up to 13-bit resolution at ±16 g
  • 32 level output data FIFO minimizes host processor load
  • Built in motion detection functions
  • Tap/Double Tap detection
  • Activity/Inactivity monitoring
  • Free-Fall detection
  • Supply and I/O voltage range: 1.8 V to 3.6 V
  • SPI (3 and 4 wire) and I2C digital interfaces
  • Flexible interrupt modes – any interrupt mappable to either interrupt pin

The ADXL345 motion sensor includes an on-chip FIFO (first-in/first-out) memory block that stores up to 32 sample sets of X, Y, and Z data. By sampling input data to determine if the system should be actively responding to a change in movement or acceleration, the new motion sensing devices save additional system power by off-loading that function from the host processor. Typically, a host processor consumes a dominant amount of system power budget, so allowing it to remain in sleep mode as long as possible can dramatically decrease overall power usage upwards of 75% of the budget, when utilized effectively.

More info: ADXL345 Small, Ultra Low Power, 3-Axis, Digital Accelerometer (pdf)