Analog Devices' ADXL345 ultra-low-power digital accelerometer has an output data range that scales from 0.1Hz to 3.2kHz, unlike competing devices, which have fixed 100Hz, 400Hz, or 1kHz data rates. This allows portable system designers to better manage energy consumption by precisely allocating power for a given system function and reserving unused power for other uses. The ADXL345 measures dynamic acceleration resulting from motion or shock and with a 10,000-g shock rating is well suited for applications such as hard-disk drive protection in personal computers.
Featuring resolution of 4-milli-g/LSB (least-significant bit) across all g ranges, single tap and double tap detection, activity and inactivity detection, free fall detection, and user-programmable threshold levels, the new accelerometer also includes I2C and three- and four-wire SPI (serial peripheral interface) digital interfaces and a voltage range of 1.8V to 3.6V.
The ADXL345 motion sensor incorporates 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. The ADXL345 is supplied in a small, thin, 3 mm × 5 mm × 1 mm, 14-lead, plastic package.
- Ultralow power: as low as 40µA in measurement mode and 0.1µA in standby mode at VS = 2.5V (typical)
- Power consumption scales automatically with bandwidth
- User-selectable resolution, fixed 10-bit resolution, or full resolution, where resolution increases with g range, up to 13-bit resolution at ±16 g (maintaining 4 mg/LSB scale factor in all g ranges)
- Embedded, patent pending FIFO technology minimizes host
- Tap/double tap detection
- Activity/inactivity monitoring
- Free-fall detection
- Supply voltage range: 2.0V to 3.6V
- I/O voltage range: 1.7V to VS
- Medical instrumentation
- Pointing devices
- Industrial instrumentation
- Personal navigation devices
- Hard disk drive (HDD) protection
- Fitness equipment