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Dual-Axis, High-g,
iMEMS
®
Accelerometers
ADXL278
FEATURES
Complete dual-axis acceleration measurement system on a
single monolithic IC
Available in ±35
g/±35 g,
±50
g/±50 g,
or ±70
g/±35 g
output
full-scale ranges
Full differential sensor and circuitry for high resistance to
EMI/RFI
Environmentally robust packaging
Complete mechanical and electrical self-test on digital
command
Output ratiometric to supply
Sensitive axes in the plane of the chip
High linearity (0.2% of full scale)
Frequency response down to dc
Low noise
Low power consumption
Tight sensitivity tolerance and 0
g
offset capability
Largest available prefilter clipping headroom
400 Hz, 2-pole Bessel filter
Single-supply operation
Compatible with Sn/Pb and Pb-free solder processes
Qualified for automotive applications
GENERAL DESCRIPTION
The ADXL278 is a low power, complete, dual-axis
accelerometer with signal conditioned voltage outputs that are
on a single monolithic IC. This product measures acceleration
with a full-scale range of (X-axis/Y-axis) ±35
g/±35 g,
±50
g/
±50
g,
or ±70
g/±35 g
(minimum). The ADXL278 can also
measure both dynamic acceleration (vibration) and static
acceleration (gravity).
The ADXL278 is the fourth-generation surface micromachined
iMEMS®
accelerometer from ADI with enhanced performance
and lower cost. Designed for use in front and side impact airbag
applications, this product also provides a complete cost-
effective solution useful for a wide variety of other applications.
The ADXL278 is temperature stable and accurate over the
automotive temperature range, with a self-test feature that fully
exercises all the mechanical and electrical elements of the sensor
with a digital signal applied to a single pin.
The ADXL278 is available in a 5 mm × 5 mm × 2 mm,
8-terminal ceramic LCC package.
APPLICATIONS
Vibration monitoring and control
Vehicle collision sensing
Shock detection
FUNCTIONAL BLOCK DIAGRAM
ADXL278
EXC
V
S
V
DD
V
DD2
V
DD3
DIFFERENTIAL
SENSOR
DEMOD
AMP
400Hz
BESSEL
FILTER
X
OUT
TIMING
GENERATOR
EXC
DIFFERENTIAL
SENSOR
DEMOD
AMP
400Hz
BESSEL
FILTER
Y
OUT
SELF-TEST
Figure 1.
Rev. B
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.
www.analog.com
Tel: 781.329.4700
Fax: 781.461.3113
©2010 Analog Devices, Inc. All rights reserved.
05365-001
ADXL278
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
Theory of Operation .........................................................................7
Applications........................................................................................8
Power Supply Decoupling ............................................................8
Self-Test ..........................................................................................8
Clock Frequency Supply Response .............................................8
Signal Distortion ...........................................................................8
Outline Dimensions ..........................................................................9
ADXL278 Ordering Guide ...........................................................9
Automotive Products ....................................................................9
REVISION HISTORY
8/10—Rev. A to Rev. B
Updated Format .................................................................. Universal
Change to Features Section ............................................................. 1
Updated Outline Dimensions ......................................................... 9
Changes to Ordering Guide ............................................................ 9
Added Automotive Products Section............................................. 9
7/02—Rev. D to Rev. E
Edits to Features ................................................................................ 1
5/05—Rev. 0 to Rev. A
Rev. B | Page 2 of 12
ADXL278
SPECIFICATIONS
1
At T
A
= −40°C to +105°C, 5.0 V dc ± 5%, acceleration = 0
g,
unless otherwise noted.
Table 1.
Parameter
SENSOR
Output Full-Scale Range
Nonlinearity
Package Alignment Error
Sensor-to-Sensor
Alignment Error
Cross-Axis Sensitivity
Resonant Frequency
Sensitivity, Ratiometric
(Over Temperature)
OFFSET
Zero-g Output Voltage
(Over Temperature)
2
NOISE
Noise Density
Conditions
I
OUT
≤ ±100 µA
Model No. AD22284
Min
Typ Max
37
0.2
1
0.1
−5
V
DD
= 5 V,
100 Hz
52.25
24
55
2
Model No. AD22285
Min
Typ Max
55
0.2
1
0.1
−5
36.1
24
38
2
Model No. AD22286
Axis Min
Typ Max
X
Y
70
37
0.2
1
0.1
−5
X
Y
V
OUT
− V
DD
/2,
V
DD
= 5 V
−150
+150
−150
+150
X
Y
10 Hz − 400 Hz,
5V
1.1
3
1.4
3
X
Y
Clock Noise
FREQUENCY RESPONSE
−3 dB Frequency
−3 dB Frequency Drift
SELF-TEST
Output Change
(Cube vs. V
DD
)
3
Logic Input High
Logic Input Low
Input Resistance
OUTPUT AMPLIFIER
Output Voltage Swing
Capacitive Load Drive
PREFILTER HEADROOM
CFSR @ 400 kHz
POWER SUPPLY (V
DD
)
Functional Range
Quiescent Supply Current
TEMPERATURE RANGE
1
2
Unit
g
g
%
Degree
Degree
%
kHz
mV/g
mV/g
mV
mV
mg/√Hz
mg/√Hz
mV p-p
Hz
Hz
2
+5
57.75
+5
39.9
+5
24
27
55
28.35
57.75
+100
+150
1.8
1.1
5
3.5
3
25.65
52.25
−100
−150
5
2-pole Bessel
360
25°C to
T
MIN
or T
MAX
V
DD
= 5 V
440
400
2
440
360
5
400
2
440
360
400
2
440
550
660
304
380
456
X
Y
216
440
3.5
30
270
550
324
660
1
mV
mV
V
V
kΩ
V
DD
= 5 V
V
DD
= 5 V
Pull-down
resistor to GND
I
OUT
= ±400 µA
3.5
1
30
50
3.5
1
30
50
50
0.25
1000
280
6
4.75
3.5
V
DD
−
0.25
0.25
1000
400
4.5
V
DD
−
0.25
0.25
1000
560
3
6
V
DD
−
0.25
V
pF
g
V/V
V/V
V
V
mA
°C
V
DD
= 5 V
−40
2.2
5.25
6
2.9
+105
4.75
3.5
2.2
−40
5.25
6
2.9
+105
4.75
3.5
2.2
−40
5.25
6
2.9
+105
All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed.
Zero
g
output is ratiometric.
3
Self-test output at V
DD
= (Self-Test Output at 5 V) × (V
DD
/5 V)
3
.
Rev. B | Page 3 of 12
ADXL278
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)
Operating Temperature Range
Storage Temperature
Rating
4,000
g
4,000
g
−0.3 V to +7.0 V
(COM − 0.3 V) to
(V
S
+ 0.3 V)
Indefinite
−65°C to +150°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. B | Page 4 of 12
Test/Measurement
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