Data Sheet
FEATURES
3-Axis, ±2
g/±4 g/±8 g/±16 g
Ultralow
Power Digital MEMS Accelerometer
ADXL344
GENERAL DESCRIPTION
The
ADXL344
is a versatile 3-axis, digital-output, low
g
MEMS
accelerometer. Selectable measurement range and bandwidth and
configurable, built-in motion detection make it suitable for sensing
acceleration in a wide variety of applications. Robustness to
10,000
g
of shock and a wide temperature range (−40°C to +85°C)
enable use of the accelerometer even in harsh environments.
The
ADXL344
measures acceleration with high resolution (13-bit)
measurement at up to ±16
g.
Digital output data is formatted as
16-bit twos complement and is accessible through either a SPI
(3- or 4-wire) or I
2
C digital interface. The
ADXL344
can
measure the static acceleration of gravity in tilt-sensing appli-
cations, as well as dynamic acceleration resulting from motion
or shock. Its high resolution (3.9 mg/LSB) enables measurement
of inclination changes less than 1.0°.
Several special sensing functions are provided. Activity and
inactivity sensing detect the presence or lack of motion. Tap
sensing detects single and double taps in any direction. Free-fall
sensing detects if the device is falling. Orientation detection
reports four- and six-position orientation and can trigger an
interrupt upon change in orientation. These functions can be
mapped individually to either of two interrupt output pins.
An integrated memory management system with a 32-level first in,
first out (FIFO) buffer can be used to store data to minimize host
processor activity and lower overall system power consumption.
The
ADXL344
is supplied in a small, thin, 3 mm × 3 mm ×
0.95 mm, 16-terminal, plastic package.
Multipurpose accelerometer with 10- to 13-bit resolution for
use in a wide variety of applications
Digital output accessible via SPI (3- and 4-wire) and I
2
C
Built-in motion detection features make tap, double-tap,
activity, inactivity, orientation, and free-fall detection
trivial
User-adjustable thresholds
Interrupts independently mappable to two interrupt pins
Low power operation down to 23 µA and embedded FIFO for
reducing overall system power
Wide supply and I/O voltage range: 1.7 V to 2.75 V
Wide operating temperature range (−40°C to +85°C)
10,000
g
shock survival
Small, thin Pb free, RoHS compliant 3 mm × 3 mm × 0.95 mm
LGA package
APPLICATIONS
Handsets
Gaming and pointing devices
Hard disk drive (HDD) protection
FUNCTIONAL BLOCK DIAGRAM
V
S
V
DD I/O
ADXL344
POWER
MANAGEMENT
SENSE
ELECTRONICS
3-AXIS
SENSOR
ADC
DIGITAL
FILTER
CONTROL
AND
INTERRUPT
LOGIC
INT1
INT2
32-LEVEL
FIFO
SDA/SDI/SDIO
SERIAL I/O
SDO/ALT
ADDRESS
10628-001
SCL/SCLK
GND
CS
Figure 1.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2012 Analog Devices, Inc. All rights reserved.
ADXL344
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings ............................................................ 5
Thermal Resistance ...................................................................... 5
Package Information .................................................................... 5
ESD Caution .................................................................................. 5
Pin Configuration and Function Descriptions ............................. 6
Typical Performance Characteristics ............................................. 7
Theory of Operation ...................................................................... 10
Power Sequencing ...................................................................... 10
Power Savings.............................................................................. 11
Serial Communications ................................................................. 12
SPI ................................................................................................. 12
I
2
C ................................................................................................. 15
Interrupts ..................................................................................... 17
FIFO ............................................................................................. 18
Self-Test........................................................................................ 19
Register Map.................................................................................... 20
Data Sheet
Register Definitions ................................................................... 21
Applications Information .............................................................. 27
Power Supply Decoupling ......................................................... 27
Mechanical Considerations for Mounting .............................. 27
Tap Detection .............................................................................. 27
Improved Tap Detection............................................................ 28
Tap Sign ....................................................................................... 28
Threshold .................................................................................... 29
Link Mode ................................................................................... 29
Sleep Mode vs. Low Power Mode............................................. 29
Offset Calibration ....................................................................... 29
Using Self-Test ............................................................................ 30
Orientation Sensing ................................................................... 31
Data Formatting of Upper Data Rates ..................................... 32
Noise Performance ..................................................................... 33
Operation at Voltages Other Than 2.6 V ................................ 33
Offset Performance at Lowest Data Rates ............................... 34
Axes of Acceleration Sensitivity ............................................... 35
Layout and Design Recommendations ................................... 36
Outline Dimensions ....................................................................... 37
Ordering Guide .......................................................................... 37
REVISION HISTORY
4/12—Revision 0: Initial Version
Rev. 0 | Page 2 of 40
Data Sheet
SPECIFICATIONS
ADXL344
T
A
= 25°C, V
S
= 2.6 V, V
DD I/O
= 1.8 V, acceleration = 0
g,
C
S
= 10 μF tantalum, C
I/O
= 0.1 μF, output data rate (ODR) = 800 Hz, unless
otherwise noted.
Table 1.
Parameter
SENSOR INPUT
Measurement Range
Nonlinearity
Inter-Axis Alignment Error
Cross-Axis Sensitivity
3
OUTPUT RESOLUTION
All
g
Ranges
±2
g
Range
±4
g
Range
±8
g
Range
±16
g
Range
SENSITIVITY
Sensitivity at X
OUT
, Y
OUT
, Z
OUT
Test Conditions/Comments
Each axis
User selectable
Percentage of full scale
Min
1
Typ
2
±2, ±4, ±8, ±16
±0.5
±0.1
±1
10
10
11
12
13
256
256
128
64
32
±1.0
3.9
3.9
7.8
15.6
31.2
±0.02
±35
±1.0
ODR = 100 Hz for ±2
g,
10-bit
resolution or all
g
ranges, full
resolution
User selectable
0.10
0.27
−1.55
0.40
1.7
1.7
ODR ≥ 100 Hz
ODR < 10 Hz
ODR = 3200 Hz
2.6
1.8
140
30
0.2
1.4
1.5
Max
1
Unit
g
%
Degrees
%
Bits
Bits
Bits
Bits
Bits
LSB/g
LSB/g
LSB/g
LSB/g
LSB/g
%
mg/LSB
mg/LSB
mg/LSB
mg/LSB
mg/LSB
%/°C
mg
mg/°C
LSB rms
Sensitivity Deviation from Ideal
Scale Factor at X
OUT
, Y
OUT
, Z
OUT
Each axis
10-bit resolution
Full resolution
Full resolution
Full resolution
Full resolution
Each axis
All
g
ranges, full resolution
±2
g,
10-bit resolution
±4
g,
10-bit resolution
±8
g,
10-bit resolution
±16
g,
10-bit resolution
All
g
ranges
All
g
ranges, full resolution
±2
g,
10-bit resolution
±4
g,
10-bit resolution
±8
g,
10-bit resolution
±16
g,
10-bit resolution
Each axis
Sensitivity Change Due to Temperature
0
g
OFFSET
0
g
Output Deviation from Ideal for X-, Y-, Z-Axes
0
g
Offset vs. Temperature for X-, Y-, Z-Axes
NOISE
X-, Y-, Z-Axes
OUTPUT DATA RATE AND BANDWIDTH
Output Data Rate (ODR)
4, 5, 6, 7
SELF-TEST
8
Output Change in X-Axis
Output Change in Y-Axis
Output Change in Z-Axis
POWER SUPPLY
Operating Voltage Range (V
S
)
Interface Voltage Range (V
DD I/O
)
Measurement Mode Supply Current
Standby Mode Supply Current
Turn-On and Wake-Up Time
9
3200
1.55
−0.27
1.95
2.75
V
S
Hz
g
g
g
V
V
µA
µA
µA
ms
Rev. 0 | Page 3 of 40
ADXL344
Parameter
TEMPERATURE
Operating Temperature Range
WEIGHT
Device Weight
1
2
Data Sheet
Test Conditions/Comments
Min
1
−40
18
Typ
2
Max
1
+85
Unit
°C
mg
All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed.
The typical specifications shown are for at least 68% of the population of parts and are based on the worst case of mean ±1 σ except for 0
g
output and sensitivity,
which represents the target value. For 0
g
offset and sensitivity, the deviation from the ideal describes the worst case of mean ±1 σ.
3
Cross-axis sensitivity is defined as coupling between any two axes.
4
Bandwidth is the −3 dB frequency and is half the output data rate bandwidth = ODR/2.
5
The output format for the 3200 Hz and 1600 Hz ODRs is different from the output format for the remaining ODRs. This difference is described in the Data Formatting of
Upper Data Rates section.
6
Output data rates below 6.25 Hz exhibit additional offset shift with increased temperature, depending on selected output data rate. Refer to the Offset Performance at
Lowest Data Rates section for details.
7
These are typical values for the lowest and highest output data rate settings.
8
Self-test change is defined as the output (g) when the SELF_TEST bit = 1 (in the DATA_FORMAT register, Address 0x31) minus the output (g) when the SELF_TEST bit = 0.
Due to device filtering, the output reaches its final value after 4 × τ when enabling or disabling self-test, where τ = 1/(data rate). The part must be in normal power
operation (LOW_POWER bit = 0 in the BW_RATE register, Address 0x2C) for self-test to operate correctly.
9
Turn-on and wake-up times are determined by the user-defined bandwidth. At a 100 Hz data rate, the turn-on and wake-up times are each approximately 11.1 ms. For
other data rates, the turn-on and wake-up times are each approximately τ + 1.1 in milliseconds, where τ = 1/(data rate).
Rev. 0 | Page 4 of 40
Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Acceleration
Any Axis, Unpowered
Any Axis, Powered
V
S
V
DD I/O
Digital Pins
All Other Pins
Output Short-Circuit Duration
(Any Pin to Ground)
Temperature Range
Powered
Storage
Rating
10,000
g
10,000
g
−0.3 V to +3.0 V
−0.3 V to +3.0 V
−0.3 V to V
DD I/O
+ 0.3 V or
3.0 V, whichever is less
−0.3 V to +3.0 V
Indefinite
ADXL344
PACKAGE INFORMATION
The information in Figure 2 and Table 4 provide details about
the package branding for the
ADXL344.
For a complete listing
of product availability, see the Ordering Guide section.
Y4S
10628-047
vvvv
Table 4. Package Branding Information
Branding Key
Y4S
vvvv
−40°C to +105°C
−40°C to +105°C
Figure 2. Product Information on Package (Top View)
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Field Description
Part identifier for the
ADXL344
Factory lot code
ESD CAUTION
THERMAL RESISTANCE
Table 3. Package Characteristics
Package Type
16-Terminal LGA
θ
JA
150°C/W
θ
JC
85°C/W
Device Weight
18 mg
Rev. 0 | Page 5 of 40
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