Document Outline
- Specifications
- Pinout
- Package Drawings
- Ordering Guide
- Features
- Applications
- Product Description
- Absolute Maximum Ratings
- Functional Block Diagram
- Pin Function Description
- Circuit Description
- Typical Characteristics
- PIN FUNCTION DESCRIPTIONS
- CAUTION
- DEFINITIONS
- THEORY OF OPERATION
- APPLICATIOns POWER SUPPLY DECOUPLING
- MICROCOMPUTER INTERFACES
- DESIGN TRADE-OFFS FOR SELECTING FILTER
- CHOOSING T2 AND COUNTER FREQUENCY: DESIGN TRADE-OFFS
- MEASURING 360 OF TILT
- STRATEGIES FOR USING THE DUTY CYCLE OUTPUT
- WITH MICROCONTROLLERS
- USING THE ANALOG OUTPUT
- USING THE ADXL202E IN VERY LOW POWER APPLICATIONS
- CALIBRATING THE ADXL202E/ADXL210
- APPLICATIONS
- DIAGRAMS
- Typical Output Duty Cycle
- Block Diagram
- Figure 2.
- Using a Two-Axis Accelerometer to Measure 360 of Tilt
- How the X and Y Axes Respond to Changes in Tilt
REV. A
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.
a
ADXL202E*
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., 2000
Low-Cost 2
g Dual-Axis Accelerometer
with Duty Cycle Output
FUNCTIONAL BLOCK DIAGRAM
ANALOG
TO
DUTY
CYCLE
(ADC)
C
O
U
N
T
E
R
P
X
OUT
Y
OUT
DEMOD
DEMOD
R
FILT
32k
R
FILT
32k
ADXL202E
R
SET
T2
C
Y
Y
FILT
SELF-TEST
X
FILT
C
X
OSCILLATOR
COM
Y SENSOR
X SENSOR
3V TO 5.25V
V
DD
C
DC
T1
T2
A(g) = (T1/T2 0.5)/12.5%
0g = 50% DUTY CYCLE
T2 = R
SET
/125M
FEATURES
2-Axis Acceleration Sensor on a Single IC Chip
5 mm 5 mm 2 mm Ultrasmall Chip Scale Package
2 m
g Resolution at 60 Hz
Low-Power < 0.6 mA
Direct Interface to Low-Cost Microcontrollers via
Duty Cycle Output
BW Adjustment with a Single Capacitor
3 V to 5.25 V Single Supply Operation
1000
g Shock Survival
APPLICATIONS
2-Axis Tilt Sensing with Faster Response than
Electrolytic, Mercury, or Thermal Sensors
Computer Peripherals
Information Appliances
Alarms and Motion Detectors
Disk Drives
Vehicle Security
GENERAL DESCRIPTION
The ADXL202E is a low-cost, low-power, complete 2-axis acceler-
ometer with a digital output, all on a single monolithic IC. It is an
improved version of the ADXL202AQC/JQC. The ADXL202E
will measure accelerations with a full-scale range of 2 g. The
ADXL202E can measure both dynamic acceleration (e.g., vibra-
tion) and static acceleration (e.g., gravity).
The outputs are analog voltage or digital signals whose duty cycles
(ratio of pulsewidth to period) are proportional to acceleration.
The duty cycle outputs can be directly measured by a micro-
processor counter, without an A/D converter or glue logic. The
duty cycle period is adjustable from 0.5 ms to 10 ms via a single
resistor (R
SET
).
*Patents Pending
The typical noise floor is 200 g
Hz, allowing signals below
2 mg (at 60 Hz bandwidth) to be resolved.
The bandwidth of the accelerometer is set with capacitors C
X
and
C
Y
at the X
FILT
and Y
FILT
pins. An analog output can be recon-
structed by filtering the duty cycle output.
The ADXL202E is available in 5 mm 5 mm 2 mm 8-lead
hermetic LCC package.
REV. A
2
ADXL202ESPECIFICATIONS
TPC
1
ADXL202JE
ADXL202AE
Parameter
Conditions
Graph
Min
Typ
Max
Min
Typ
Max
Unit
SENSOR INPUT
Each Axis
Measurement Range
2
2
2
g
Nonlinearity
Best Fit Straight Line
0.2
0.2
% of FS
Alignment Error
3
X
1
1
Degrees
Alignment Error
X Sensor to Y Sensor
0.01
0.01
Degrees
Cross-Axis Sensitivity
4
X
2
2
%
SENSITIVITY
Each Axis
Duty Cycle per g
T1/T2, V
DD
= 5 V
X
10.5
12.5
14.5
10
12.5
15
%/g
Duty Cycle per g
T1/T2, V
DD
= 3 V
X
9.0
11
13.0
8.5
11
13.5
%/g
Sensitivity X
FILT
, Y
FILT
V
DD
= 5 V
X
265
312
360
250
312
375
mV/g
Sensitivity X
FILT
, Y
FILT
V
DD
= 3 V
X
140
167
195
140
167
200
mV/g
Temperature Drift
5
Delta from 25 C
X
0.5
0.5
%
ZERO g BIAS LEVEL
Each Axis
0 g Duty Cycle
T1/T2, V
DD
= 5 V
X
34
50
66
30
50
70
%
0 g Duty Cycle
T1/T2, V
DD
= 3 V
X
31
50
69
31
50
69
%
0 g Voltage X
FILT
, Y
FILT
V
DD
= 5 V
X
2.1
2.5
2.9
2.0
2.5
3.0
V
0 g Voltage X
FILT
, Y
FILT
V
DD
= 3 V
X
1.2
1.5
1.8
1.2
1.5
1.8
V
0 g Duty Cycle vs. Supply
X
1.0
4.0
1.0
4.0
%/V
0 g Offset vs. Temperature
5
Delta from 25 C
X
2.0
2.0
mg/ C
NOISE PERFORMANCE
Noise Density
@ 25 C
X
200
200
1000
gHz rms
FREQUENCY RESPONSE
3 dB Bandwidth
At Pins X
FILT
, Y
FILT
6
6
kHz
Sensor Resonant Frequency
10
10
kHz
FILTER
R
FILT
Tolerance
32 k
Nominal
15
15
%
Minimum Capacitance
At Pins X
FILT
, Y
FILT
1000
1000
pF
SELF-TEST
Duty Cycle Change
Self-Test "0" to "1"
10
10
%
DUTY CYCLE OUTPUT STAGE
F
SET
R
SET
= 125 k
0.7
1.3
0.7
1.3
kHz
Output High Voltage
I = 25
A
V
S
200 mV
V
S
200 mV
V
Output Low Voltage
I = 25
A
200
200
mV
T2 Drift vs. Temperature
50
50
ppm/ C
Rise/Fall Time
200
200
ns
POWER SUPPLY
Operating Voltage Range
3
5.25
3.0
5.25
V
Quiescent Supply Current
0.6
1.0
0.6
1.0
mA
Turn-On Time
C
FILT
in
F
160 C
FILT
+ 0.3
160 C
FILT
+ 0.3
ms
TEMPERATURE RANGE
Specified Performance AE
40
+85
C
Operating Range
0
70
40
+85
C
NOTES
1
Typical Performance Characteristics.
2
Guaranteed by measurement of initial offset and sensitivity.
3
Alignment error is specified as the angle between the true and indicated axis of sensitivity (see TPC 15).
4
Cross-axis sensitivity is the algebraic sum of the alignment and the inherent sensitivity errors.
5
Defined as the output change from ambient to maximum temperature or ambient to minimum temperature.
Specifications subject to change without notice.
(T
A
= T
MIN
to T
MAX
, T
A
= 25 C for J Grade only, V
DD
= 5 V, R
SET
= 125 k ,
Acceleration = 0
g, unless otherwise noted.)
REV. A
ADXL202E
3
ABSOLUTE MAXIMUM RATINGS
*
Acceleration (Any Axis, Unpowered for 0.5 ms) . . . . . . 1000 g
Acceleration (Any Axis, Powered for 0.5 ms) . . . . . . . . . . 500 g
+V
S
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +6.0 V
Output Short Circuit Duration, (Any Pin 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 per ma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicate in the opera tional
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
Package Characteristics
Package
Weight
JA
JC
Device
8-Lead LCC
120
C/W
tbd
C/W
<1.0 grams
ORDERING GUIDE
No.
Specified
Temperature
Package
Package
Model
of Axes
Voltage
Range
Description
Option
ADXL202JE
2
3 V to 5 V
0 to 70 C
8-Lead LCC
E-8
ADXL202AE
2
3 V to 5 V
40 C to +85 C
8-Lead LCC
E-8
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 ADXL202E features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
PIN FUNCTION DESCRIPTIONS
Pin
No.
Mnemonic
Description
1
ST
Self-Test
2
T2
Connect R
SET
to Set T2 Period
3
COM
Common
4
Y
OUT
Y-Channel Duty Cycle Output
5
X
OUT
X-Channel Duty Cycle Output
6
Y
FILT
Y-Channel Filter Pin
7
X
FILT
X-Channel Filter Pin
8
V
DD
3 V to 5.25 V
Drops onto hard surfaces can cause shocks of greater than 1000 g
and exceed the absolute maximum rating of the device. Care
should be exercised in handling to avoid damage.
PIN CONFIGURATION
1
2
3
5
4
6
7
8
ST
T2
COM
X
OUT
Y
FILT
X
FILT
V
DD
Y
OUT
BOTTOM VIEW
REV. A
ADXL202E
4
Typical Performance Characteristics*
VOLTS
16
8
0
1.28
PERCENT OF PARTS
2
4
6
10
12
14
1.32
1.36
1.41
1.45
1.49
1.53
1.58
1.62
1.66
TPC 1. X-Axis Zero g Bias Distribution at X
FILT
, V
DD
= 3 V
VOLTS
10
0
1.25
PERCENT OF PARTS
2
4
6
8
12
14
16
1.31
1.36
1.42
1.48
1.59
1.65
1.53
TPC 2. Y-Axis Zero g Bias Distribution at Y
FILT
, V
DD
= 3 V
V/g
25
10
0
0.142
PERCENT OF PARTS
5
15
20
0.148
0.155
0.162
0.169
0.176
0.182
0.189
TPC 3. X-Axis Sensitivity Distribution at X
FILT
, V
DD
= 3 V
V
DD
= 3 V
V
DD
= 5 V
*Data taken from 4500 parts over 3 lots minimum.
VOLTS
18
10
0
2.05
PERCENT OF PARTS
2
4
6
8
12
14
16
2.14
2.23
2.31
2.40
2.48
2.57
2.65
2.74
2.82
TPC 4. X-Axis Zero g Bias Distribution at X
FILT
, V
DD
= 5 V
VOLTS
25
10
0
2.05
PERCENT OF PARTS
5
15
20
2.14
2.23
2.31
2.40
2.48
2.57
2.65
2.74
2.82
TPC 5. Y-Axis Zero g Bias Distribution at Y
FILT
, V
DD
= 5 V
V/g
25
10
0
0.26
PERCENT OF PARTS
5
15
20
0.28
0.29
0.30
0.32
0.33
0.34
TPC 6. X-Axis Sensitivity Distribution at X
FILT
, V
DD
= 5 V
REV. A
ADXL202E
5
V/g
25
10
0
0.142
PERCENT OF PARTS
5
15
20
0.148
0.155
0.162
0.169
0.176
0.182
0.189
TPC 7. Y-Axis Sensitivity Distribution at Y
FILT
, V
DD
= 3 V
PERCENT DUTY CYCLE/g
25
15
0
9.50
PERCENT OF PARTS
5
20
9.90
10.4
10.8
11.8
10
11.3
12.2
12.7
30
TPC 8. X-Axis Sensitivity at X
OUT
, V
DD
= 3 V
PERCENT DUTY CYCLE/g
0
9.50
PERCENT OF PARTS
2
9.90
10.4
10.8
11.8
4
11.3
12.2
12.7
20
6
8
10
12
14
16
18
TPC 9. Y-Axis Sensitivity at Y
OUT
, V
DD
= 3 V
V
DD
= 3 V
V
DD
= 5 V
V/g
25
10
0
0.26
PERCENT OF PARTS
5
15
20
0.27
0.29
0.30
0.31
0.33
0.34
0.35
TPC 10. Y-Axis Sensitivity Distribution at Y
FILT
, V
DD
= 5 V
PERCENT DUTY CYCLE/g
25
15
0
10.3
PERCENT OF PARTS
5
20
10.8
11.3
11.8
12.8
10
12.3
13.3
13.8
TPC 11. X-Axis Sensitivity at X
OUT
, V
DD
= 5 V
PERCENT DUTY CYCLE/g
25
15
0
10.6
PERCENT OF PARTS
5
20
11.0
11.6
12.0
13.0
10
12.6
13.6
14.0
TPC 12. Y-Axis Sensitivity at Y
OUT
, V
DD
= 5 V
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