High performance, single-/dual-axis accelerometer on
a single IC chip
5 mm × 5 mm × 2 mm LCC package
1 mg resolution at 60 Hz
Low power: 700 μA at V
High zero g bias stability
High sensitivity accuracy
−40°C to +125°C temperature range
X and Y axes aligned to within 0.1° (typical)
Bandwidth adjustment with a single capacitor
Single-supply operation
3500 g shock survival
RoHS compliant
Compatible with Sn/Pb- and Pb-free solder processes
Qualified for automotive applications
APPLICATIONS
Vehicle dynamic controls
Electronic chassis controls
Platform stabilization/leveling
Navigation
Alarms and motion detectors
High accuracy, 2-axis tilt sensing
Vibration monitoring and compensation
Abuse event detection
= 5 V (typical)
S
Dual-Axis iMEMS
®
Accelerometer
ADXL103/ADXL203
GENERAL DESCRIPTION
The ADXL103/ADXL203 are high precision, low power, complete
single- and dual-axis accelerometers with signal conditioned
voltage outputs, all on a single, monolithic IC. The ADXL103/
ADXL203 measure acceleration with a full-scale range of ±1.7 g,
±5 g, or ±18 g. The ADXL103/ADXL203 can measure both
dynamic acceleration (for example, vibration) and static
acceleration (for example, gravity).
The typical noise floor is 110 μg/√Hz, allowing signals below 1 mg
(0.06° of inclination) to be resolved in tilt sensing applications
using narrow bandwidths (<60 Hz).
The user selects the bandwidth of the accelerometer using
Capacitor C
Bandwidths of 0.5 Hz to 2.5 kHz can be selected to suit the
application.
The ADXL103 and ADXL203 are available in a 5 mm × 5 mm ×
2 mm, 8-terminal ceramic LCC package.
and Capacitor CY at the X
X
OUT
and Y
OUT
pins.
FUNCTIONAL BLOCK DIAGRAMS
+5V
V
S
ADXL103
C
DC
SENSOR
COMSTX
Rev. D
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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.
Changes to Ordering Guide.......................................................... 12
2/06—Rev. 0 to Rev. A
Changes to Features..........................................................................1
Changes to Table 1.............................................................................3
Changes to Figure 2...........................................................................4
Changes to Figure 3 and Figure 4....................................................5
Changes to the Performance Section..............................................9
4/04—Revision 0: Initial Version
Rev. D | Page 2 of 16
Page 3
Data Sheet ADXL103/ADXL203
SPECIFICATIONS
TA = −40°C to +125°C, VS = 5 V, CX = CY = 0.1 μF, acceleration = 0 g, unless otherwise noted. All minimum and maximum specifications
are guaranteed. All typical specifications are not guaranteed.
Table 1.
ADXL103/ADXL203 AD22293 AD22035/AD22037
Parameter Test Conditions Min Typ Max Min Typ Max Min Typ Max Unit
SENSOR Each axis
Measurement Range1 ±1.7 ±5 ±6 ±18
Nonlinearity % of full scale ±0.2 ±1.25 ±0.2 ±1.25 ±0.2 ±1.25 %
Package Alignment Error ±1 ±1 ±1 Degrees
Alignment Error (ADXL203) X to Y sensor ±0.1 ±0.1 ±0.1 Degrees
Cross-Axis Sensitivity ±1.5 ±3 ±1.5 ±3 ±1.5 ±3 %
SENSITIVITY (RATIOMETRIC)2 Each axis
Sensitivity at X
Sensitivity Change Due to
Temperature
, Y
V
OUT
OUT
3
= 5 V 960 1000 1040 293 312 331 94 100 106 mV/g
S
VS = 5 V ±0.3 ±0.3 ±0.3
ZERO g BIAS LEVEL (RATIOMETRIC) Each axis
0 g Voltage at X
Initial 0 g Output Deviation
, Y
V
OUT
OUT
= 5 V 2.4 2.5 2.6 2.4 2.5 2.6 2.4 2.5 2.6 V
S
V
= 5 V, 25°C ±25 ±50 ±125 mg
S
From Ideal
0 g Offset vs. Temperature ±0.1 ±0.8 ±0.3 ±1.8 ±1 mg/°C
NOISE
Output Noise <4 kHz, VS = 5 V 1 3 1 3 2 mV rms
Noise Density 110 200 130
FREQUENCY RESPONSE4
CX, CY Range5 0.002 10 0.002 10 0.002 10 μF
R
Tolerance 24 32 40 24 32 40 24 32 40 kΩ
FILT
Sensor Resonant Frequency 5.5 5.5 5.5 kHz
SELF TEST6
Logic Input Low 1 1 1 V
Logic Input High 4 4 4 V
ST Input Resistance to GND 30 50 30 50 30 50 kΩ
Output Change at X
, Y
ST 0 to ST 1 450 750 1100 125 250 375 60 80 100 mV
OUT
OUT
OUTPUT AMPLIFIER
Output Swing Low No load 0.05 0.2 0.05 0.2 0.05 0.2 V
Output Swing High No load 4.5 4.8 4.5 4.8 4.5 4.8 V
POWER SUPPLY (VDD)
Operating Voltage Range 3 6 3 6 3 6 V
Quiescent Supply Current 0.7 1.1 0.7 1.1 0.7 1.1 mA
Turn-On Time7 20 20 20 ms
1
Guaranteed by measurement of initial offset and sensitivity.
2
Sensitivity is essentially ratiometric to VS. For VS = 4.75 V to 5.25 V, sensitivity is 186 mV/V/g to 215 mV/V/g.
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 capacitor (CX, CY).
5
Bandwidth = 1/(2 × π × 32 kΩ × C). For CX, CY = 0.002 μF, bandwidth = 2500 Hz. For CX, CY = 10 μF, bandwidth = 0.5 Hz. Minimum/maximum values are not tested.
6
Self-test response changes cubically with VS.
7
Larger values of CX, CY increase turn-on time. Turn-on time is approximately 160 × CX or CY + 4 ms, where CX, CY are in μF.
g
%
μg/√Hz
rms
Rev. D | Page 3 of 16
Page 4
ADXL103/ADXL203 Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
Acceleration (Any Axis, Unpowered) 3500 g
Acceleration (Any Axis, Powered) 3500 g
Drop Test (Concrete Surface) 1.2 m
VS −0.3 V to +7.0 V
All Other Pins
Output Short-Circuit Duration
(COM − 0.3 V) to
(V
+ 0.3 V)
S
Indefinite
(Any Pin to Common)
Temperature Range (Powered) −55°C to +125°C
Temperature Range (Storage) −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.
T
P
T
L
T
SMAX
RAMP-UP
Table 3. Package Characteristics
Package Type θJA θ
Device Weight
JC
8-Terminal Ceramic LCC 120°C/W 20°C/W <1.0 gram
ESD CAUTION
CRITICAL ZONE
TO T
t
P
T
L
P
t
L
T
SMIN
TEMPERAT URE
t
S
PREHEAT
t
25°C TO PE AK
Figure 2. Recommended Soldering Profile
RAMP-DOWN
TIME
03757-102
Table 4. Solder Profile Parameters
Test Condition
Profile Feature Sn63/Pb37 Pb-Free
Average Ramp Rate (TL to TP) 3°C/second maximum 3°C/second maximum
Preheat
Minimum Temperature (T
Maximum Temperature (T
Time (T
T
to TL
SMAX
SMIN
to T
) (tS) 60 seconds to 120 seconds 60 seconds to 150 seconds
SMAX
) 100°C 150°C
SMIN
) 150°C 200°C
SMAX
Ramp-Up Rate 3°C/second 3°C/second
Time Maintained above Liquidous (TL)
Liquidous Temperature (TL) 183°C 217°C
Time (tL) 60 seconds to 150 seconds 60 seconds to 150 seconds
Peak Temperature (TP) 240°C + 0°C/−5°C 260°C + 0°C/−5°C
Time Within 5°C of Actual Peak Temperature (tP) 10 seconds to 30 seconds 20 seconds to 40 seconds
Ramp-Down Rate 6°C/second maximum 6°C/second maximum
Time 25°C to Peak Temperature 6 minutes maximum 8 minutes maximum
Rev. D | Page 4 of 16
Page 5
Data Sheet ADXL103/ADXL203
.
.
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
ADXL103
TOP VIEW
(Not to Scale)
V
S
8
1
ST
NC
2
COM
3
NOTES
1. NC = NO CONNECT . DO NOT CONNECT TO THIS PI N
Figure 3. ADXL103 Pin Configuration
7
X
+X
4
NC
OUT
6
NC
5
NC
03757-002
NOTES
1. NC = NO CONNECT . DO NOT CONNECT TO THIS PIN
Figure 4. ADXL203 Pin Configuration
ST
NC
COM
ADXL203
TOP VIEW
(Not to Scale)
V
S
8
1
+Y
2
+X
3
4
NC
7
X
OUT
6
Y
OUT
5
NC
03757-003
Table 5. ADXL103 Pin Function Descriptions
Pin No. Mnemonic Description
1 ST Self Test
2 NC Do Not Connect
3 COM Common
4 NC Do Not Connect
5 NC Do Not Connect
6 NC Do Not Connect
7 X
X Channel Output
OUT
8 VS 3 V to 6 V
Table 6. ADXL203 Pin Function Descriptions
Pin No. Mnemonic Description
1 ST Self Test
2 NC Do Not Connect
3 COM Common
4 NC Do Not Connect
5 NC Do Not Connect
6 Y
7 X
Y Channel Output
OUT
X Channel Output
OUT
8 VS 3 V to 6 V
Rev. D | Page 5 of 16
Page 6
ADXL103/ADXL203 Data Sheet
A
TYPICAL PERFORMANCE CHARACTERISTICS
ADXL103 AND ADXL203
VS = 5 V for all graphs, unless otherwise noted.
25
30
20
15
10
5
PERCENT OF POPULATION (%)
0
–0.10
–0.08
–0.06
–0.04
0
–0.02
ZERO g BIAS (V)
0.02
0.04
Figure 5. X-Axis Zero g Bias Deviation from Ideal at 25°C
30
25
20
15
10
PERCENT OF POPULATION (%)
5
25
20
15
10
PERCENT OF POPULATION (%)
5
03757-010
0.06
0.08
0.10
0
–0.10
–0.08
–0.06
–0.04
0
–0.02
ZERO g BIAS (V)
0.02
0.04
0.06
03757-013
0.08
0.10
Figure 8. Y-Axis Zero g Bias Deviation from Ideal at 25°C
25
20
TION (%)
15
10
PERCENT OF POPUL
5
0
–0.80
–0.70
–0.60
–0.40
–0.30
–0.50
TEMPERATURE COEFFICIENT (mg/°C)
0
0.10
–0.20
–0.10
0.20
Figure 6. X-Axis Zero g Bias Temperature Coefficient
40
35
30
25
20
15
10
PERCENT OF POPULATION (%)
5
0
0.94
0.95
0.96
0.98
0.99
1.00
1.01
0.97
SENSITIVITY (V/g)
1.02
Figure 7. X-Axis Sensitivity at 25°C
03757-011
0.30
0.40
0.50
0.60
0.70
0.80
0
–0.80
–0.70
–0.60
–0.40
–0.30
–0.50
TEMPERATURE COEFFICIENT (mg/°C)
0
0.10
0.20
0.30
0.40
–0.20
–0.10
0.50
03757-014
0.60
0.70
0.80
Figure 9. Y-Axis Zero g Bias Temperature Coefficient
40
35
30
25
20
15
10
PERCENT OF POPULATION (%)
5
03757-012
1.03
1.04
1.05
1.06
0
0.94
0.95
0.96
0.98
0.99
1.00
1.01
1.02
1.03
0.97
SENSITIVITY (V/g)
1.04
03757-015
1.05
1.06
Figure 10. Y-Axis Sensitivity at 25°C
Rev. D | Page 6 of 16
Page 7
Data Sheet ADXL103/ADXL203
2.60
2.58
2.56
2.54
2.52
2.50
2.48
VOLTAGE (1V/g)
2.46
2.44
2.42
2.40
–50
–40
–30
0
–20
–10
1020305040
TEMPERATURE (°C)
607080
Figure 11. Zero g Bias vs. Temperature; Parts Soldered to PCB
50
45
40
35
30
25
20
15
10
PERCENT OF POPULATI ON (%)
5
0
X AXIS NOISE DENSITY (mg/√Hz)
Figure 12. X-Axis Noise Density at 25°C
1.03
1.02
1.01
)
g
1.00
0.99
SENSITIVITY (V/
0.98
90
100
03757-004
110
120
130
0.97
0
–20
–10
1020305040
TEMPERATURE (°C)
–40
–30
–50
607080
90
100
03757-016
110
120
130
Figure 13. Sensitivity vs. Temperature; Parts Soldered to PCB
50
45
40
35
30
25
20
15
10
PERCENT OF POPULATI ON (%)
5
03757-007
15014013012011010090807060
0
Y AXIS NOISE DENSITY (mg/√Hz)
03757-008
15014013012011010090807060
Figure 14. Y-Axis Noise Density at 25°C
Rev. D | Page 7 of 16
Page 8
ADXL103/ADXL203 Data Sheet
45
40
35
30
25
20
15
10
PERCENT OF POPULATION (%)
5
0
0.40
0.45
0.50
0.65
0.60
0.70
0.55
SELF-TEST OUTPUT (V)
0.75
0.80
0.85
0.90
03757-017
0.95
1.00
Figure 15. X-Axis Self-Test Response at 25°C
0.90
0.85
0.80
)
0.75
g
0.70
0.65
VOLTAGE (1V/
0.60
0.55
0.50
0
–50
–40
–30
–20
–10
1020305040
TEMPERATURE (°C)
607080
90
100
03757-103
110
120
130
Figure 16. Self-Test Response vs. Temperature
45
40
35
30
25
20
15
10
PERCENT OF POPULATION (%)
5
0
0.40
0.45
0.50
0.65
0.60
0.70
0.55
SELF-TEST OUTPUT (V)
0.75
0.80
0.85
0.90
03757-019
0.95
1.00
Figure 17. Y-Axis Self-Test Response at 25°C
100
90
80
70
60
50
40
30
20
PERCENT OF POPULATION (%)
10
0
200
3V
300
400
5V
500
600
CURRENT (µA)
03757-018
700
800
900
1000
Figure 18. Supply Current at 25°C
Rev. D | Page 8 of 16
Page 9
Data Sheet ADXL103/ADXL203
A
A
A
A
A
A
AD22293
60
70
50
40
TION (%)
30
20
PERCENT OF POPUL
10
0
2.43
2.44
2.45
2.46
2.47
2.48
2.49
2.50
2.51
2.52
2.53
2.54
2.55
2.56
2.57
ZERO g BIAS (V)
03757-117
Figure 19. X-Axis Zero g Bias at 25°C
25
20
TION (%)
15
10
60
50
TION (%)
40
30
20
PERCENT OF POPUL
10
0
2.43
2.44
2.45
2.46
2.47
2.48
2.49
2.50
2.51
2.52
2.53
2.54
2.55
2.56
ZERO g BIAS (V)
2.57
03757-119
Figure 22. Y-Axis Zero g Bias at 25°C
25
20
TION (%)
15
10
PERCENT OF POPUL
5
0
–1.2
–1.0
–0.8
–0.6
TEMPERATURE COEFFICI ENT (mg/°C)
0
0.2
–0.4
–0.2
0.4
Figure 20. X-Axis Zero g Bias Temperature Coefficient
90
80
70
60
TION (%)
50
40
30
20
PERCENT OF POPUL
10
0
0.287
0.297
0.307
0.317
0.327
0.337
SENSITIVITY (V/g)
0.347
Figure 21. X-Axis Sensitivity at 25°C
0.357
0.6
0.8
1.0
1.2
03757-118
0.367
0.377
0.387
03757-021
PERCENT OF POPUL
5
0
–1.2
–1.0
–0.8
–0.6
TEMPERATURE COEFFICIENT (mg/°C)
0
0.2
–0.4
–0.2
0.4
Figure 23. Y-Axis Zero g Bias Temperature Coefficient
80
70
60
TION (%)
50
40
30
20
PERCENT OF POPUL
10
0
0.287
0.297
0.307
0.317
0.327
0.337
SENSITIVITY (V/g)
0.347
Figure 24. Y-Axis Sensitivity at 25°C
0.6
0.8
1.0
1.2
03757-020
0.357
0.367
0.377
0.387
03757-022
Rev. D | Page 9 of 16
Page 10
ADXL103/ADXL203 Data Sheet
A
A
A
A
A
A
AD22035 AND AD22037
60
60
50
TION
40
30
20
PERCENT OF POPUL
10
0
–50
–40
–30
–20
0
–10
ZERO g BIAS (mV)
10
20
30
Figure 25. X-Axis Zero g Bias Deviation from Ideal at 25°C
35
30
25
TION
20
15
10
PERCENT OF POPUL
5
50
TION
40
30
20
PERCENT OF POPUL
10
0
40
50
03757-105
–50
–40
–30
–20
0
–10
ZERO g BIAS (mV)
10
20
30
40
50
03757-108
Figure 28. Y-Axis Zero g Bias Deviation from Ideal at 25°C
35
30
25
TION
20
15
10
PERCENT OF POPUL
5
0
–2.5
–3.0
–1.5
–2.0
TEMPERATURE COEFFICIENT (mg/°C)
0
1.0
0.5
–1.0
–0.5
1.5
Figure 26. X-Axis Zero g Bias Temperature Coefficient
25
20
TION
15
10
PERCENT OF POPUL
5
0
97
98
99
SENSITIVITY (mV/g)
100
101
Figure 27. X-Axis Sensitivity at 25°C
0
2.5
2.0
3.5
3.0
03757-106
–2.5
–3.0
–1.5
–2.0
TEMPERATURE COEFFICIENT (mg/°C)
0
1.0
0.5
1.5
2.5
2.0
–1.0
–0.5
3.0
03757-009
Figure 29. Y-Axis Zero g Bias Temperature Coefficient
25
20
TION
15
10
PERCENT OF POPUL
5
0
97
102
103
98
03757-107
99
100
SENSITIVITY (mV/g)
101
102
103
03757-110
Figure 30. Y-Axis Sensitivity at 25°C
Rev. D | Page 10 of 16
Page 11
Data Sheet ADXL103/ADXL203
A
A
A
40
35
30
TION
25
20
15
10
PERCENT OF POPUL
5
0
0.060
0.065
0.070
0.075
0.080
SELF-TEST OUTPUT (V)
0.085
Figure 31. X-Axis Self Test Response at 25°C
101.0
100.5
100.0
99.5
99.0
SENSITIVITY (mV)
98.5
98.0
97.5
–50–2502550751001 25
TEMPERATURE (°C)
Figure 32. Sensitivity vs. Temperature; Parts Soldered to PCB
0.090
0.095
0.100
03757-111
03757-112
TION
PERCENT OF POPUL
TION
PERCENT OF POPUL
45
40
35
30
25
20
15
10
5
0
0.060
0.065
0.070
0.075
SELF-TEST OUTPUT (V)
Figure 33. Y-Axis Self Test Response at 25°C
90
80
70
60
50
40
30
20
10
0
25°C105°C
680
700
720
740
760
780
CURRENT (µA)
800
Figure 34. Supply Current vs. Temperature
0.080
820
840
0.085
0.090
0.095
0.100
03757-114
900
920
860
880
940
960
03757-113
Rev. D | Page 11 of 16
Page 12
ADXL103/ADXL203 Data Sheet
%
m
%
ALL MODELS
40
40
35
)
30
25
20
15
10
PERCENT OF POPULATION (
5
0
–4.0
–5.0
–3.0
–2.0
PERCENT SENSITIVITY (%)
–1.0
0
1.0
2.0
3.0
4.0
5.0
09781-023
Figure 35. Z vs. X Cross-Axis Sensitivity
0.9
0.8
0.7
A)
0.6
CURRENT (
0.5
0.4
VS=5V
VS=3V
35
)
30
25
20
15
10
PERCENT OF POPULATION (
5
0
–4.0
–5.0
–3.0
–2.0
PERCENT SENSITIVITY (%)
–1.0
0
1.0
2.0
3.0
4.0
5.0
09781-026
Figure 37. Z vs. Y Cross-Axis Sensitivity
VOLTAGE (V)
0.3
TEMPERATURE (°C)
Figure 36. Supply Current vs. Temperature
150100500–50
09781-024
Figure 38. Turn-On Time; C
TIME
, CY = 0.1 μF, Time Scale = 2 ms/DIV
X
09781-027
Rev. D | Page 12 of 16
Page 13
Data Sheet ADXL103/ADXL203
THEORY OF OPERATION
The ADXL103/ADXL203 are complete acceleration measurement
systems on a single, monolithic IC. The ADXL103 is a single-
axis accelerometer, and the ADXL203 is a dual-axis accelerometer.
Both parts contain a polysilicon surface-micro-machined sensor
and signal conditioning circuitry to implement an open-loop
acceleration measurement architecture. The output signals are
analog voltages that are proportional to acceleration. The
ADXL103/ADXL203 are capable of measuring both positive
and negative accelerations from ±1.7 g to at least ±18 g. The
accelerometer can measure static acceleration forces, such
as gravity, allowing it to be used as a tilt sensor.
The sensor is a surface-micromachined polysilicon structure
built on top of the silicon wafer. Polysilicon springs suspend the
structure over the surface of the wafer and provide a resistance
against acceleration forces. Deflection of the structure is measured
using a differential capacitor that consists of independent fixed
plates and plates attached to the moving mass. The fixed plates
are driven by 180° out-of-phase square waves. Acceleration deflects
the beam and unbalances the differential capacitor, resulting in an
output square wave whose amplitude is proportional to acceleration.
Phase-sensitive demodulation techniques are then used to rectify
the signal and determine the direction of the acceleration.
PIN 8
X
OUT
Y
OUT
= –1g
= 0g
The output of the demodulator is amplified and brought off-chip
through a 32 kΩ resistor. At this point, the user can set the signal
bandwidth of the device by adding a capacitor. This filtering
improves measurement resolution and helps prevent aliasing.
PERFORMANCE
Rather than using additional temperature compensation circuitry,
innovative design techniques have been used to ensure that
high performance is built in. As a result, there is essentially no
quantization error or nonmonotonic behavior, and temperature
hysteresis is very low (typically less than 10 mg over the −40°C
to +125°C temperature range).
Figure 11 shows the 0 g output performance of eight parts
(x and y axes) over a −40°C to +125°C temperature range.
Figure 13 demonstrates the typical sensitivity shift over
temperature for V
V
= 5 V but is still very good over the specified range; it is
S
typically better than ±1% over temperature at V
= 5 V. Sensitivity stability is optimized for
S
= 3 V.
S
PIN 8
= 0g
X
OUT
= +1g
Y
OUT
TOP VIEW
(Not to Scale)
PIN 8
X
= +1g
OUT
= 0g
Y
OUT
PIN 8
= 0g
X
OUT
= –1g
Y
OUT
X
OUT
Y
OUT
EARTH’S SURFACE
= 0g
= 0g
03757-028
Figure 39. Output Response vs. Orientation
Rev. D | Page 13 of 16
Page 14
ADXL103/ADXL203 Data Sheet
APPLICATIONS INFORMATION
POWER SUPPLY DECOUPLING
For most applications, a single 0.1 μF capacitor, CDC, adequately
decouples the accelerometer from noise on the power supply.
However, in some cases, particularly where noise is present at
the 140 kHz internal clock frequency (or any harmonic thereof),
noise on the supply can cause interference on the ADXL103/
ADXL203 output. If additional decoupling is needed, a 100 Ω
(or smaller) resistor or ferrite beads can be inserted in the supply
line of the ADXL103/ADXL203. Additionally, a larger bulk
bypass capacitor (in the 1 μF to 22 μF range) can be added in
parallel to C
DC
.
SETTING THE BANDWIDTH USING CX AND CY
The ADXL103/ADXL203 has provisions for band limiting the
X
OUT
and Y
pins. Capacitors must be added at these pins to
OUT
implement low-pass filtering for antialiasing and noise reduction.
The equation for the 3 dB bandwidth is
= 1/(2π(32 kΩ) × C
f
–3 dB
(X, Y)
)
or more simply,
f
= 5 μF/C
–3 dB
The tolerance of the internal resistor (R
(X, Y)
) can vary typically as
FILT
much as ±25% of its nominal value (32 kΩ); thus, the bandwidth
varies accordingly. A minimum capacitance of 2000 pF for C
C
is required in all cases.
Y
Table 7. Filter Capacitor Selection, C
and CY
X
and
X
Bandwidth (Hz) Capacitor (μF)
1 4.7
10 0.47
50 0.10
100 0.05
200 0.027
500 0.01
SELF TEST
The ST pin controls the self test feature. When this pin is set to VS,
an electrostatic force is exerted on the beam of the accelerometer.
The resulting movement of the beam allows the user to test if
the accelerometer is functional. The typical change in output is
750 mg (corresponding to 750 mV). This pin can be left opencircuit or connected to common in normal use.
Never expose the ST pin to voltages greater than V
the system design is such that this condition cannot be guaranteed
(that is, multiple supply voltages are present), a low V
diode between ST and V
is recommended.
S
+ 0.3 V. If
S
clamping
F
DESIGN TRADE-OFFS FOR SELECTING FILTER
CHARACTERISTICS: THE NOISE/BANDWIDTH
TRADE-OFF
The accelerometer bandwidth selected ultimately determines
the measurement resolution (smallest detectable acceleration).
Filtering can be used to lower the noise floor, improving the
resolution of the accelerometer. Resolution is dependent on
the analog filter bandwidth at X
The output of the ADXL103/ADXL203 has a typical bandwidth
of 2.5 kHz. The user must filter the signal at this point to limit
aliasing errors. The analog bandwidth must be no more than
half the analog-to-digital sampling frequency to minimize
aliasing. The analog bandwidth can be further decreased to
reduce noise and improve resolution.
The ADXL103/ADXL203 noise has the characteristics of white
Gaussian noise, which contributes equally at all frequencies and is
described in terms of μg/√Hz (that is, the noise is proportional to
the square root of the accelerometer bandwidth). Limit bandwidth
to the lowest frequency needed by the application to maximize the
resolution and dynamic range of the accelerometer.
With the single-pole roll-off characteristic, the typical noise of
the ADXL103/ADXL203 is determined by
rmsNoise = (110 μg/√Hz) × (
At 100 Hz, the noise is
rmsNoise = (110 μg/√Hz) × (
Often, the peak value of the noise is desired. Peak-to-peak noise
can only be estimated by statistical methods. Table 8 is useful
for estimating the probabilities of exceeding various peak values,
given the rms value.
Table 8. Estimation of Peak-to-Peak Noise
% of Time That Noise Exceeds
Peak-to-Peak Value
Nominal Peak-to-Peak Value
2 × rms 32
4 × rms 4.6
6 × rms 0.27
8 × rms 0.006
Peak-to-peak noise values give the best estimate of the uncertainty
in a single measurement; peak-to-peak noise is estimated by
6 × rms. Table 9 gives the typical noise output of the ADXL103/
USING THE ADXL103/ADXL203 WITH OPERATING
VOLTAGES OTHER THAN 5 V
The ADXL103/ADXL203 is tested and specified at VS = 5 V;
however, it can be powered with V
as 6 V. Some performance parameters change as the supply
voltage is varied.
The ADXL103/ADXL203 output is ratiometric, so the output
sensitivity (or scale factor) varies proportionally to the supply
voltage. At V
= 3 V, the output sensitivity is typically 560 mV/g.
S
The zero g bias output is also ratiometric, so the zero g output is
nominally equal to V
/2 at all supply voltages.
S
The output noise is not ratiometric but is absolute in volts;
therefore, the noise density decreases as the supply voltage
increases. This is because the scale factor (mV/g) increases
while the noise voltage remains constant. At V
noise density is typically 190 μg/√Hz.
Self test response in g is roughly proportional to the square of
the supply voltage. However, when ratiometricity of sensitivity
is factored in with supply voltage, self test response in volts is
roughly proportional to the cube of the supply voltage. So at
V
= 3 V, the self test response is approximately equivalent to
S
150 mV or equivalent to 270 mg (typical).
The supply current decreases as the supply voltage decreases.
Typical current consumption at V
as low as 3 V or as high
S
= 3 V, the
S
= 3 V is 450 μA.
DD
USING THE ADXL203 AS A DUAL-AXIS TILT SENSOR
One of the most popular applications of the ADXL203 is tilt
measurement. An accelerometer uses the force of gravity as an
input vector to determine the orientation of an object in space.
An accelerometer is most sensitive to tilt when its sensitive axis
is perpendicular to the force of gravity, that is, parallel to the
earth’s surface. At this orientation, its sensitivity to changes in
tilt is highest. When the accelerometer is oriented on axis to
gravity, that is, near its +1 g or –1 g reading, the change in
output acceleration per degree of tilt is negligible. When the
accelerometer is perpendicular to gravity, its output changes
nearly 17.5 mg per degree of tilt. At 45°, its output changes at
only 12.2 mg per degree, and resolution declines.
Dual-Axis Tilt Sensor: Converting Acceleration to Tilt
When the accelerometer is oriented so both its x-axis and y-axis
are parallel to the earth’s surface, it can be used as a 2-axis tilt sensor
with a roll axis and a pitch axis. Once the output signal from the
accelerometer has been converted to an acceleration that varies
between –1 g and +1 g, the output tilt in degrees is calculated as
PITCH = ASIN(A
ROLL = ASIN(A
Be sure to account for overranges. It is possible for the
accelerometers to output a signal greater than ±1 g due to
vibration, shock, or other accelerations.
Specified
Voltage (V) Temperature Range Package Description
1
3
0.019 SQ
(PLATING OPTION1,
SEE DETAILA
FOROPTION2)
0.028
0.020 DIA
0.012
0.106
0.100
0.094
05-21-2010-D
Package
Option
AUTOMOTIVE PRODUCTS
The ADXL103W, ADW22035, ADXL203W, ADW22293, and ADW22037 models are available with controlled manufacturing to support
the quality and reliability requirements of automotive applications. Note that these automotive models may have specifications that differ
from the commercial models; therefore, designers should review the Specifications section of this data sheet carefully. Only the automotive grade
products shown are available for use in automotive applications. Contact your local Analog Devices account representative for specific
product ordering information and to obtain the specific Automotive Reliability reports for these models.