Date: 01/04/2009

Accelerometer sensors with built in FIFO memory block

There is new trend of off-loading few processing and other data-handling task to sensor device itself. The sensor can have the built in semiconductor device to do some preliminary processing and to convert the sensed data to industry standard bus architecture to interface directly to microcontroller.

The twin benefits of this trend are, processor is relieved from a routine processing task, where the sensed data is continuously tracked for some checks and its more reliable and accurate. It's just like having a smart supervisor on a production floor of a manufacturing company who will take care of minor issues without interrupting his boss. These types of sensors are smart sensors.

One such new smart sensor released by Analog Devices is ADXL346 accelerometer based smart sensor for measuring motions such as tilt, shock, vibration, and rotation in portable devices and moving systems. These sensors are generally used to protect the moving devices whenever some unwanted motions occur while the products embedding this sensor is in action.

The smart part of ADXL346 is, it features an on-chip FIFO (first-in/first-out) memory block that stores up to 32 sample sets of X-, Y-, and Z-axis data and effectively off-loads the FIFO function from the host processor. This allows the host processor and other power hungry peripherals to go into a sleep mode until needed saving significant system power. Analog Devices claims, effective use of this feature can dramatically decrease overall power usage by up to 75 percent.

ADXL346 specifications are designed keeping in view of limited power and space budget available for portable-electronics design engineers. With the physical dimensions 3mm x 3mm x 0.95mm, this Micro Electro Mechanical Systems (MEMS) based sensor can work up to a voltage down to 1.8-Volts.
The power saving features include, it automatically modulates its power consumption in proportion to its output data rate and can go in to sleep mode and stand-by mode.

ADXL346 has a resolution 4 mg/LSB enabling measurement of inclination changes down to 0.25 degrees. The ADXL346 measures both dynamic acceleration resulting from motion or shock and static acceleration, such as gravity, which allows it to be used as a tilt sensor.

"Motion sensing has moved beyond the initial concept of just acceleration and now includes tilt, shock, vibration, and rotation," said Bill Murphy, product line director for Micromachined Products, Analog Devices. "The cost effective measurement of these forces while consuming very little of the power budget has enabled a new wave of innovative product features and capabilities."


Availability: Now in samples volumes in August 2009
Package: 16-lead LGA package
Price: Each at US$3.04 in 1K units