Small, Low Power, 3-Axis ±5
g
Accelerometer
ADXL325
FEATURES
3-axis sensing
Small, low profile package
4 mm × 4 mm × 1.45 mm LFCSP
Low power: 350 μA typical
Single-supply operation: 1.8 V to 3.6 V
10,000
g
shock survival
Excellent temperature stability
Bandwidth adjustment with a single capacitor per axis
RoHS/WEEE lead-free compliant
GENERAL DESCRIPTION
The ADXL325 is a small, low power, complete 3-axis accelerometer
with signal conditioned voltage outputs. The product measures
acceleration with a minimum full-scale range of ±5
g.
It can
measure the static acceleration of gravity in tilt-sensing applications,
as well as dynamic acceleration, resulting from motion, shock,
or vibration.
The user selects the bandwidth of the accelerometer using
the C
X
, C
Y
, and C
Z
capacitors at the X
OUT
, Y
OUT
, and Z
OUT
pins.
Bandwidths can be selected to suit the application with a range
of 0.5 Hz to 1600 Hz for X and Y axes and a range of 0.5 Hz to
550 Hz for the Z axis.
The ADXL325 is available in a small, low profile, 4 mm ×
4 mm × 1.45 mm, 16-lead, plastic lead frame chip scale package
(LFCSP_LQ).
APPLICATIONS
Cost-sensitive, low power, motion- and tilt-sensing applications
Mobile devices
Gaming systems
Disk drive protection
Image stabilization
Sports and health devices
FUNCTIONAL BLOCK DIAGRAM
+3V
V
S
ADXL325
OUTPUT AMP
3-AXIS
SENSOR
C
DC
AC AMP
DEMOD
OUTPUT AMP
~32kΩ
X
OUT
C
X
~32kΩ
Y
OUT
C
Y
OUTPUT AMP
~32kΩ
Z
OUT
C
Z
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
©2009 Analog Devices, Inc. All rights reserved.
07946-001
COM
ST
ADXL325
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
ESD Caution .................................................................................. 4
Pin Configuration and Function Descriptions ............................. 5
Typical Performance Characteristics ............................................. 6
Theory of Operation ...................................................................... 10
Mechanical Sensor...................................................................... 10
Performance ................................................................................ 10
Applications Information .............................................................. 11
Power Supply Decoupling ......................................................... 11
Setting the Bandwidth Using C
X
, C
Y
, and C
Z
.......................... 11
Self Test ........................................................................................ 11
Design Trade-Offs for Selecting Filter Characteristics: The
Noise/BW Trade-Off .................................................................. 11
Use with Operating Voltages Other Than 3 V .......................... 11
Axes of Acceleration Sensitivity ............................................... 12
Layout and Design Recommendations ................................... 13
Outline Dimensions ....................................................................... 14
Ordering Guide .......................................................................... 14
REVISION HISTORY
8/09—Revision 0: Initial Version
Rev. 0 | Page 2 of 16
ADXL325
SPECIFICATIONS
T
A
= 25°C, V
S
= 3 V, C
X
= C
Y
= C
Z
= 0.1 μF, acceleration = 0
g,
unless otherwise noted. All minimum and maximum specifications are
guaranteed. Typical specifications are not guaranteed.
Table 1.
Parameter
SENSOR INPUT
Measurement Range
Nonlinearity
Package Alignment Error
Interaxis Alignment Error
Cross-Axis Sensitivity
1
SENSITIVITY (RATIOMETRIC)
2
Sensitivity at X
OUT
, Y
OUT
, Z
OUT
Sensitivity Change Due to Temperature
3
ZERO
g
BIAS LEVEL (RATIOMETRIC)
0
g
Voltage at X
OUT
, Y
OUT
, Z
OUT
0
g
Offset vs. Temperature
NOISE PERFORMANCE
Noise Density X
OUT
, Y
OUT,
Z
OUT
FREQUENCY RESPONSE
4
Bandwidth X
OUT
, Y
OUT 5
Bandwidth Z
OUT5
R
FILT
Tolerance
Sensor Resonant Frequency
SELF TEST
6
Logic Input Low
Logic Input High
ST Actuation Current
Output Change at X
OUT
Output Change at Y
OUT
Output Change at Z
OUT
OUTPUT AMPLIFIER
Output Swing Low
Output Swing High
POWER SUPPLY
Operating Voltage Range
Supply Current
Turn-On Time
7
TEMPERATURE
Operating Temperature Range
1
2
Conditions
Each axis
Percent of full scale
Min
±5
Typ
±6
±0.2
±1
±0.1
±1
174
±0.01
1.5
±1
250
Max
Unit
g
%
Degrees
Degrees
%
Each axis
V
S
= 3 V
V
S
= 3 V
V
S
= 3 V
156
192
mV/g
%/°C
V
mg/°C
μg/√Hz rms
Hz
Hz
kΩ
kHz
V
V
μA
mV
mV
mV
V
V
1.3
1.7
No external filter
No external filter
1600
550
32 ± 15%
5.5
+0.6
+2.4
+60
−190
+190
+320
0.1
2.8
1.8
3.6
350
1
−40
+85
Self test 0 to 1
Self test 0 to 1
Self test 0 to 1
No load
No load
−90
+90
+90
−350
+350
+580
V
S
= 3 V
No external filter
V
μA
ms
°C
Defined as coupling between any two axes.
Sensitivity is essentially ratiometric to V
S
.
3
Defined as the output change from ambient-to-maximum temperature or ambient-to-minimum temperature.
4
Actual frequency response controlled by user-supplied external filter capacitors (C
X
, C
Y
, C
Z
).
5
Bandwidth with external capacitors = 1/(2 × π × 32 kΩ × C). For C
X
, C
Y
= 0.003 μF, bandwidth = 1.6 kHz. For C
Z
= 0.01 μF, bandwidth = 500 Hz. For C
X
, C
Y
, C
Z
= 10 μF,
bandwidth = 0.5 Hz.
6
Self test response changes cubically with V
S
.
7
Turn-on time is dependent on C
X
, C
Y
, C
Z
and is approximately 160 × C
X
or C
Y
or C
Z
+ 1 ms, where C
X
, C
Y
, C
Z
are in μF.
Rev. 0 | Page 3 of 16
ADXL325
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Acceleration (Any Axis, Unpowered)
Acceleration (Any Axis, Powered)
V
S
All Other Pins
Output Short-Circuit Duration
(Any Pin to Common)
Temperature Range (Powered)
Temperature Range (Storage)
Rating
10,000
g
10,000
g
−0.3 V to +3.6 V
(COM − 0.3 V) to (V
S
+ 0.3 V)
Indefinite
−55°C to +125°C
−65°C to +150°C
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.
ESD CAUTION
Rev. 0 | Page 4 of 16
ADXL325
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
NC
16
15
14
NC
ST
COM
NC
1
2
3
4
5
ADXL325
TOP VIEW
(Not to Scale)
+Y
+Z
+X
6
7
8
NC
13
12
11
10
9
V
S
V
S
X
OUT
NC
Y
OUT
NC
COM
COM
COM
Z
OUT
NC = NO CONNECT
Figure 2. Pin Configuration
Table 3. Pin Function Descriptions
Pin No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
EP
Mnemonic
NC
ST
COM
NC
COM
COM
COM
Z
OUT
NC
Y
OUT
NC
X
OUT
NC
V
S
V
S
NC
Exposed pad
Description
No Connect (or Optionally Ground)
Self Test
Common
No Connect
Common
Common
Common
Z Channel Output
No Connect (or Optionally Ground)
Y Channel Output
No Connect
X Channel Output
No Connect
Supply Voltage (1.8 V to 3.6 V)
Supply Voltage (1.8 V to 3.6 V)
No Connect
Not internally connected. Solder for mechanical integrity.
Rev. 0 | Page 5 of 16
07946-003
