a
5
g
to 50
g,
Low Noise, Low Power,
Single/Dual Axis
i
MEM
S
®
Accelerometers
ADXL150/ADXL250
FUNCTIONAL BLOCK DIAGRAMS
TP
(DO NOT CONNECT)
+V
S
0.1 F
SENSOR
+V
S
2
FEATURES
Complete Acceleration Measurement System
on a Single Monolithic IC
80 dB Dynamic Range
Pin Programmable 50
g
or 25
g
Full Scale
Low Noise: 1 m
g
/√Hz Typical
Low Power: <2 mA per Axis
Supply Voltages as Low as 4 V
2-Pole Filter On-Chip
Ratiometric Operation
Complete Mechanical & Electrical Self-Test
Dual & Single Axis Versions Available
Surface Mount Package
ADXL150
GAIN
AMP
5k
V
OUT
BUFFER
AMP
DEMODULATOR
25k
CLOCK
9
SELF-TEST
COM
OFFSET
NULL
X OFFSET
NULL
TP
(DO NOT CONNECT)
ADXL250
+V
S
0.1 F
SENSOR
GAIN
AMP
25k
DEMODULATOR
5k
BUFFER
AMP
V
OUT
X
GENERAL DESCRIPTION
The ADXL150 and ADXL250 are third generation
±
50
g
sur-
face micromachined accelerometers. These improved replace-
ments for the ADXL50 offer lower noise, wider dynamic range,
reduced power consumption and improved zero
g
bias drift.
The ADXL150 is a single axis product; the ADXL250 is a fully
integrated dual axis accelerometer with signal conditioning on a
single monolithic IC, the first of its kind available on the com-
mercial market. The two sensitive axes of the ADXL250 are
orthogonal (90°) to each other. Both devices have their sensitive
axes in the same plane as the silicon chip.
The ADXL150/ADXL250 offer lower noise and improved
signal-to-noise ratio over the ADXL50. Typical S/N is 80 dB,
allowing resolution of signals as low as 10 mg, yet still providing
a
±
50
g
full-scale range. Device scale factor can be increased
from 38 mV/g to 76 mV/g by connecting a jumper between
V
OUT
and the offset null pin. Zero
g
drift has been reduced to
0.4
g
over the industrial temperature range, a 10× improvement
over the ADXL50. Power consumption is a modest 1.8 mA
per axis. The scale factor and zero
g
output level are both
CLOCK
5k
GAIN
AMP
SENSOR
DEMODULATOR
25k
COM
Y OFFSET
NULL
+V
S
2
V
OUT
Y
BUFFER
AMP
SELF-TEST
ratiometric to the power supply, eliminating the need for a volt-
age reference when driving ratiometric A/D converters such as
those found in most microprocessors. A power supply bypass
capacitor is the only external component needed for normal
operation.
The ADXL150/ADXL250 are available in a hermetic 14-lead
surface mount cerpac package specified over the 0°C to +70°C
commercial and –40°C to +85°C industrial temperature ranges.
Contact factory for availability of devices specified over automo-
tive and military temperature ranges.
i
MEM
S
is a registered trademark of Analog Devices, Inc.
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1998
ADXL150/ADXL250–SPECIFICATIONS
Parameter
SENSOR
Guaranteed Full-Scale Range
Nonlinearity
Package Alignment Error
1
Sensor-to-Sensor Alignment Error
Transverse Sensitivity
2
SENSITIVITY
Sensitivity (Ratiometric)
3
Y Channel
X Channel
Sensitivity Drift Due to Temperature Delta from 25°C to T
MIN
or T
MAX
Conditions
±
40
(T
A
= +25 C for J Grade, T
A
= –40 C to +85 C for A Grade,
V
S
= +5.00 V, Acceleration = Zero
g,
unless otherwise noted)
ADXL250JQC/AQC
Min
Typ Max
±
40
±
50
0.2
±
1
±
0.1
±
2
38.0 43.0
38.0 43.0
±
0.5
Units
g
% of FS
Degrees
Degrees
%
mV/g
mV/g
%
ADXL150JQC/AQC
Min
Typ Max
±
50
0.2
±
1
±
2
33.0
38.0 43.0
±
0.5
33.0
33.0
ZERO
g
BIAS LEVEL
Output Bias Voltage
4
Zero
g
Drift Due to Temperature
ZERO-g OFFSET ADJUSTMENT
Voltage Gain
Input Impedance
NOISE PERFORMANCE
Noise Density
5
Clock Noise
FREQUENCY RESPONSE
–3 dB Bandwidth
Bandwidth Temperature Drift
Sensor Resonant Frequency
SELF-TEST
Output Change
6
Logic “1” Voltage
Logic “0” Voltage
Input Resistance
OUTPUT AMPLIFIER
Output Voltage Swing
Capacitive Load Drive
POWER SUPPLY (V
S
)
7
Functional Voltage Range
Quiescent Supply Current
TEMPERATURE RANGE
Operating Range J
Specified Performance A
Delta from 25°C to T
MIN
or T
MAX
Delta V
OUT
/Delta V
OS PIN
V
S
/2 – 0.35 V
S
/2
0.2
0.45
20
V
S
/2 + 0.35 V
S
/2 – 0.35 V
S
/2 V
S
/2 + 0.35 V
0.3
g
0.45
20
0.50 0.55
30
1
5
900
1000
50
24
0.40 0.60
1.0
30
V
S
– 0.25
0.25
1000
4.0
3.5
50
V
S
– 0.25
2.5
V/V
kΩ
mg/√Hz
mV p-p
Hz
Hz
kHz
V
V
V
kΩ
V
pF
V
mA
mA
°C
°C
0.50 0.55
30
1
5
2.5
900
T
MIN
to T
MAX
Q=5
ST Pin from Logic “0” to “1”
0.25
V
S
– 1
30
0.25
1000
4.0
ADXL150
ADXL250 (Total 2 Channels)
0
–40
1000
50
24
0.40 0.60
1.0
0.25
V
S
– 1
To Common
I
OUT
=
±100 µA
50
1.8
6.0
3.0
6.0
5.0
+70
+85
+70
+85
0
–40
NOTES
1
Alignment error is specified as the angle between the true axis of sensitivity and the edge of the package.
2
Transverse sensitivity is measured with an applied acceleration that is 90 degrees from the indicated axis of sensitivity.
3
Ratiometric: V
OUT
= V
S
/2 + (Sensitivity
×
V
S
/5 V
×
a) where a = applied acceleration in
gs,
and V
S
= supply voltage. See Figure 21. Output scale factor can be
doubled by connecting V
OUT
to the offset null pin.
4
Ratiometric, proportional to V
S
/2. See Figure 21.
5
See Figure 11 and Device Bandwidth vs. Resolution section.
6
Self-test output varies with supply voltage.
7
When using ADXL250, both Pins 13 and 14 must be connected to the supply for the device to function.
Specifications subject to change without notice.
–2–
REV. 0
ADXL150/ADXL250
ABSOLUTE MAXIMUM RATINGS*
Package Characteristics
Acceleration (Any Axis, Unpowered for 0.5 ms) . . . . . . 2000
g
Acceleration (Any Axis, Powered for 0.5 ms) . . . . . . . . . 500
g
+V
S
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7.0 V
Output Short Circuit Duration
(V
OUT
, V
REF
Terminals to Common) . . . . . . . . . . . Indefinite
Operating Temperature . . . . . . . . . . . . . . . . . –55°C to +125°C
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
*Stresses
above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; the functional operation of
the device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
Package
14-Lead Cerpac
JA
JC
Device Weight
5 Grams
110°C/W
30°C/W
ORDERING GUIDE
Model
ADXL150JQC
ADXL150AQC
ADXL250JQC
ADXL250AQC
Temperature Range
0°C to +70°C
–40°C to +85°C
0°C to +70°C
–40°C to +85°C
Drops onto hard surfaces can cause shocks of greater than 2000
g
and exceed the absolute maximum rating of the device. Care
should be exercised in handling to avoid damage.
PIN CONNECTIONS
NC
NC
NC
NC
TP (DO NOT CONNECT)
NC
COMMON
7
1
14
ADXL150
TOP VIEW
(Not to Scale)
8
V
S
NC
NC
NC
V
OUT
SELF-TEST
ZERO
g
ADJ
1
ADXL150
14
1
ADXL250
14
TOP VIEW
(Not to Scale)
A
X
TOP VIEW
(Not to Scale)
A
X
A
Y
90
7
8
7
8
POSITIVE A = POSITIVE V
OUT
POSITIVE A = POSITIVE V
OUT
NC
ZERO
g
ADJ Y
V
OUT
Y
NC
TP (DO NOT CONNECT)
NC
COMMON
7
1
14
ADXL250
TOP VIEW
(Not to Scale)
8
V
S
V
S
NC
NC
V
OUT
X
SELF-TEST
ZERO
g
ADJ X
Figure 1. ADXL150 and ADXL250 Sensitive Axis
Orientation
NC = NO CONNECT
NOTE: WHEN USING ADXL250, BOTH PINS 13 AND 14 NEED
TO BE CONNECTED TO SUPPLY FOR DEVICE TO FUNCTION
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the ADXL150/ADXL250 feature proprietary ESD protection circuitry, permanent
damage may occur on devices subjected to high energy electrostatic discharges. Therefore, pro per
ESD precautions are recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
REV. 0
–3–
ADXL150/ADXL250
GLOSSARY OF TERMS
Acceleration:
Change in velocity per unit time.
Acceleration Vector:
Vector describing the net acceleration
acting upon the ADXL150/ADXL250.
g:
A unit of acceleration equal to the average force of gravity
occurring at the earth’s surface. A
g
is approximately equal to
32.17 feet/s
2
or 9.807 meters/s
2
.
Nonlinearity:
The maximum deviation of the ADXL150/
ADXL250 output voltage from a best fit straight line fitted to a
plot of acceleration vs. output voltage, calculated as a % of the
full-scale output voltage (at 50
g).
Resonant Frequency:
The natural frequency of vibration of
the ADXL150/ADXL250 sensor’s central plate (or “beam”). At
its resonant frequency of 24 kHz, the ADXL150/ADXL250’s
moving center plate has a slight peak in its frequency response.
Sensitivity:
The output voltage change per
g
unit of accelera-
tion applied, specified at the V
OUT
pin in mV/g.
Total Alignment Error:
Net misalignment of the ADXL150/
ADXL250’s on-chip sensor and the measurement axis of the
application. This error includes errors due to sensor die align-
ment to the package, and any misalignment due to installation
of the sensor package in a circuit board or module.
Transverse Acceleration:
Any acceleration applied 90° to the
axis of sensitivity.
Transverse Sensitivity Error:
The percent of a transverse
acceleration that appears at V
OUT
.
Transverse Axis:
The axis perpendicular (90°) to the axis of
sensitivity.
Zero
g
Bias Level:
The output voltage of the ADXL150/
ADXL250 when there is no acceleration (or gravity) acting
upon the axis of sensitivity. The output offset is the difference
between the actual zero
g
bias level and (V
S
/2).
Polarity of the Acceleration Output
The polarity of the ADXL150/ADXL250 output is shown in
Figure 1. When its sensitive axis is oriented to the earth’s gravity
(and held in place), it will experience an acceleration of +1
g.
This corresponds to a change of approximately +38 mV at the
output pin. Note that the polarity will be reversed if the package
is rotated 180°. The figure shows the ADXL250 oriented so that
its “X” axis measures +1
g.
If the package is rotated 90° clock-
wise (Pin 14 up, Pin 1 down), the ADXL250’s “Y” axis will now
measure +1
g.
8
7
8
A
Y
7
A
X
14
A
X
1
14
ADXL150
ADXL250
1
Figure 2. Output Polarity
Acceleration Vectors
The ADXL150/ADXL250 is a sensor designed to measure
accelerations that result from an applied force. It responds to
the component of acceleration on its sensitive X axis (ADXL150)
or on both the “X” and “Y” axis (ADXL250).
–4–
REV. 0
ADXL150/ADXL250
Typical Characteristics
(@+5 V dc, +25 C with a 38 mV/g Scale Factor unless otherwise noted)
5.0
TYPICAL OUTPUT RESPONSE IN dB
4.0
3.0
ERROR FROM IDEAL – %
2.0
1.0
0
–1.0
–2.0
–3.0
–4.0
–5.0
4.0
4.5
5.0
5.5
POWER SUPPLY VOLTAGE
6.0
6
0
–6
–12
–18
–24
–30
–36
–42
–48
100
1k
FREQUENCY – Hz
10k
BEAM
RESONANCE
PACKAGE
RESONANCE
Figure 3. Typical Sensitivity Error from Ideal Ratiometric
Response for a Number of Units
Figure 6. Typical Output Response vs. Frequency of
ADXL150/ADXL250 on a PC Board that Has Been
Conformally Coated
2.5
2.0
1.5
ZERO
g
DRIFT – mV
4.5
5.0
SUPPLY VOLTAGE
5.5
6.0
1.0
ERROR – %
0.5
0
30
20
10
0
–0.5
–1.0
–1.5
–2.0
4.0
–10
–20
–30
–40 –30 –20 –10 0
10 20 30 40 50 60 70 80 90 100
TEMPERATURE – C
Figure 4. Offset Error of Zero g Level from Ideal
V
S
/2 Response as a Percent of Full-Scale for a Number
of Units
Figure 7. Typical Zero g Drift for a Number of Units
2.4
2.2
SUPPLY CURRENT – mA
+105 C
2
+25 C
1.8
–40 C
1.6
600g
500g
500g INPUT
400g
300g
OUTPUT RESPONSE
200g
60g
50g
40g
30g
20g
10g
0g
TIME – 0.2ms/Div
1.4
100g
0g
1.2
4
4.5
5
5.5
SUPPLY VOLTAGE – Volts
6
Figure 5. Typical Supply Current vs. Supply Voltage
Figure 8. Typical 500 g Step Recovery at the Output
REV. 0
–5–
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