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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
a
1
g to 5 g Single Chip Accelerometer
with Signal Conditioning
ADXL05*
FEATURES
5 milli-
g Resolution
Noise Level 12 Less than the ADXL50
User Selectable Full Scale from 1
g to 5 g
Output Scale Selectable from 200 mV/
g to 1 V/g
Complete Acceleration Measurement System on a
Single Chip IC
Self Test on Digital Command
+5 V Single Supply Operation
1000
g Shock Survival
APPLICATIONS
Low Cost Sensor for Vibration Measurement
Tilt Sensing with Faster Response than Electrolytic or
Mercury Sensors
More Sensitive Alarms and Motion Detectors
Affordable Inertial Sensing of Velocity and Position
floor is 500
g/
Hz
, (12
less than the ADXL50), allowing sig-
nals below 5 milli-g to be resolved. The ADXL05 is a force bal-
anced capacitive accelerometer with the capability to measure
both ac accelerations (typical of vibration) or dc accelerations
(such as inertial force or gravity). Three external capacitors and
a +5 volt regulated power supply are all that is required to
measure accelerations up to
5 g. Three resistors are used to
configure the output buffer amplifier to set scale factors from
200 mV/g to 1 V/g. External capacitors may be added to the
resistor network to provide 1 or 2 poles of filtering. No addi-
tional active components are required to interface directly to
most analog to digital converters (ADCs).
The device features a TTL compatible self-test function that
can electrostatically deflect the sensor beam at any time to verify
that the sensor and its electronics are functioning correctly.
The ADXL05 is available in a hermetic 10-pin TO-100 metal
can, specified over the 0
C to +70
C commercial, and 40
C to
+85
C industrial temperature ranges. Contact factory for avail-
ability of automotive grade devices.
*Patents pending.
Analog Devices, Inc., 1996
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
GENERAL DESCRIPTION
The ADXL05 is a complete acceleration measurement system
on a single monolithic IC. The ADXL05 will measure accelera-
tions with full-scale ranges of
5 g to
1 g or less. Typical noise
FUNCTIONAL BLOCK DIAGRAM
SENSOR
REFERENCE
6
9
10
8
3
2
1
5
7
4
DEMODULATOR
BUFFER
AMP
PREAMP
OSCILLATOR
ADXL05
C2
OSCILLATOR
DECOUPLING
CAPACITOR
C3
+5V
DEMODULATOR
CAPACITOR
C1
C1
COM
R1
VPR
VIN
R3
VREF
OUTPUT
R2
+3.4V
VOUT
SELF-TEST
(ST)
+1.8V
ADXL05SPECIFICATIONS
ADXL05J/A
Parameter
Conditions
Min
Typ
Max
Units
SENSOR INPUT
Measurement Range
Guaranteed Full Scale
5
+5
g
Nonlinearity
Best Fit Straight Line, 5 g FS
0.2
% of FS
Alignment Error
1
1
Degrees
Transverse Sensitivity
2
2
%
SENSITIVITY
Initial Sensitivity at V
PR
+25
C
175
200
225
mV/g
Initial Sensitivity at V
OUT
+25
C, R3/R1 = 5
0.875
1.000
1.125
V/g
Temperature Drift
3
0.5
% of Reading
ZERO g BIAS LEVEL
at V
PR
Initial Offset
1.50
1.80
2.10
V
vs. Temperature
3
25/40
mV
vs. Supply
V
S
= 4.75 V to 5.25 V
10
32
mV/V
NOISE PERFORMANCE
at V
PR
Voltage Noise Density
BW = 4 Hz to 1 kHz
500
1000
g/
Hz
Noise in 100 Hz Bandwidth
5
mg rms
Noise in 10 Hz Bandwidth
1.6
mg rms
FREQUENCY RESPONSE
3 dB Bandwidth
4
C1 = 0.022
F (See Figure 9)
1000
1600
Hz
3 dB Bandwidth
4
C1 = 0.010
F
4
kHz
Sensor Resonant Frequency
12
kHz
SELF TEST INPUT
Output Change at V
PR
5
ST Pin from Logic "0" to "1"
0.85
1.00
1.15
V
Logic "1" Voltage
2.0
V
Logic "0" Voltage
0.8
V
Input Resistance
To Common
50
k
+3.4 V REFERENCE
Output Voltage
3.350
3.400
3.450
V
Output Temperature Drift
3
5
mV
Power Supply Rejection
DC, V
S
= +4.75 V to +5.25 V
1
10
mV/V
Output Current
Sourcing
500
A
PREAMPLIFIER OUTPUT
Voltage Swing
0.25
V
S
1.4
V
Current Output
Source or Sink
30
80
A
Capacitive Load Drive
100
pF
BUFFER AMPLIFIER
Input Offset Voltage
6
Delta from Nominal 1.800 V
10
25
mV
Input Bias Current
5
20
nA
Open-Loop Gain
DC
80
dB
Unity Gain Bandwidth
200
kHz
Output Voltage Swing
I
OUT
=
100
A
0.25
V
S
0.25
V
Capacitive Load Drive
1000
pF
Power Supply Rejection
DC, V
S
= +4.75 V to +5.25 V
1
10
mV/V
POWER SUPPLY
Operating Voltage Range
4.75
5.25
V
Quiescent Supply Current
8.0
10.0
mA
TEMPERATURE RANGE
Operating Range J
0
+70
C
Specified Performance A
40
+85
C
Automotive Grade*
40
+125
C
NOTES
1
Alignment error is specified as the angle between the true and indicated axis of sensitivity, (see Figure 2).
2
Transverse sensitivity is measured with an applied acceleration that is 90
from the indicated axis of sensitivity. Transverse sensitivity is specified as the percent of
transverse acceleration that appears at the V
PR
output. This is the algebraic sum of the alignment and the inherent sensor sensitivity errors, (see Figure 2).
3
Specification refers to the maximum change in parameter from its initial at +25
C to its worst case value at T
MIN
to T
MAX
.
4
Frequency at which response is 3 dB down from dc response assuming an exact C1 value is used. Maximum recommended BW is 6 kHz using a 0.010
F capacitor, refer to
Figure 9.
5
Applying
logic high to the self-test input has the effect of applying an acceleration of 5 g to the ADXL05.
6
Input offset voltage is defined as the output voltage differential from 1.800 V when the amplifier is connected as a follower. The voltage at this pin has a temperature drift
proportional to that of the 3.4 V reference.
*Contact factory for availability of automotive grade devices.
All min and max specifications are guaranteed. Typical specifications are not tested or guaranteed.
Specifications subject to change without notice.
(T
A
= T
MIN
to T
MAX
, T
A
= +25 C for J Grade Only, V
S
= +5 V, @ Acceleration = 0
g,
unless otherwise noted)
2
REV. B
BUFFER
AMP
C3
0.1F
+5V
V
OUT
0.022F
C1
C1
+3.4V
REF
COM
1.8V
6
8
9
10
1
2
3
4
0.022F
C2
PRE-AMP
V
PR
R2
R3
V
IN
5
ADXL05
R1
NOMINAL VALUES:
R1 = 49.9k
R3 = 100k
(G=2)
R2 = 255k
(G=2)
DC COUPLED CONNECTION ( 2
g Full Scale)
(@ V
OUT
Terminal (Pin 9), unless otherwise noted. 0
g Bias Level = +2.5 V, C1 = 0.022 F, R2 = 2.57 R3)
ADXL05J/A
Parameter
Conditions
Min
Typ
Max
Units
Buffer Gain
G = R3/R1*
2
FULL-SCALE RANGE
2
+2
g
SENSITIVITY
@
+25
C
350
400
450
mV/g
Temperature Drift
T
MIN
to T
MAX
0.5
% of Reading
ZERO g BIAS LEVEL
@ +25
C
1.75
2.5
3.2
V
Temperature Drift
+25
C to T
MIN
or T
MAX
50/80
mV
FREQUENCY RESPONSE
dc
1000
Hz
*Note: Resistor tolerance will affect system accuracy. Use of
1% (or better) metal film resistors is recommended.
AC COUPLED CONNECTION ( 1.5
g Full Scale)
(@ V
OUT
Terminal (Pin 9), unless otherwise noted. 0
g Bias Level = +2.5 V, C1 = 0.022 F, R2 = 2.57 R3
ADXL05J/A
Parameter
Conditions
Min
Typ
Max
Units
Buffer Gain
G = R3/R1*
5
FULL-SCALE RANGE
1.5
+1.5
g
SENSITIVITY
@
+25
C
875
1000
1,125
mV/g
Temperature Drift
T
MIN
to T
MAX
0.5
% of Reading
ZERO g BIAS LEVEL
@ +25
C
2.5
V
Temperature Drift
+25
C to T
MIN
or T
MAX
2/5
mV
FREQUENCY RESPONSE
C4 = 3.3
F, R1 = 49.9 k
1
1000
Hz
*Note: Resistor tolerance will affect system accuracy. Use of
1% (or better) metal film resistors is recommended.
System Performance SpecificationsADXL05
BUFFER
AMP
C3
0.1F
+5V
V
OUT
0.022F
C1
C1
+3.4V
REF
COM
1.8V
6
8
9
10
1
2
3
4
0.022F
C2
PRE-AMP
V
PR
R2
R3
V
IN
5
ADXL05
R1
C4
NOMINAL VALUES:
R1 = 49.9k
R3 = 249k
R2 = 640k
REV. B
3
ADXL05
REV. B
4
Package Characteristics
Package
JA
JC
Device Weight
10-Pin TO-100
130
C/W
30
C/W
5 Grams
ORDERING GUIDE
Model
Temperature Range
ADXL05JH
0
C to +70
C
ADXL05AH
40
C to +85
C
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 +7.0 V
Output Short Circuit Duration
(V
PR
, 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
permanent 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.
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 ADXL05 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
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 DESCRIPTION
+5 V
The power supply input pin.
C2
Connection for an external bypass capacitor (nominally 0.022
F)
used to prevent oscillator switching noise from interfering with
other ADXL05 circuitry. Please see the section on component
selection.
C1
Connections for the demodulator capacitor, nominally 0.022
F.
See the section on component selection for application information.
COM
The power supply common (or "ground") connection.
V
REF
Output of the internal 3.4 V voltage reference.
ST
The digital self-test input. It is both CMOS and TTL compatible.
V
PR
The ADXL05 preamplifier output providing an output voltage of
200 mV per g of acceleration.
V
OUT
Output of the buffer amplifier.
V
IN
The inverting input of the uncommitted buffer amplifier.
CONNECTION DIAGRAM
10-Header (TO-100)
5
6
7
8
9
10
1
2
3
4
AXIS OF
SENSITIVITY
5
6
7
8
9
10
1
2
3
4
AXIS OF
SENSITIVITY
V
IN
V
OUT
V
PR
ST
V
REF
COM
C2
C1
C1
+5V
TOP VIEW
NOTES:
AXIS OF SENSITIVITY IS ALONG A LINE
BETWEEN PIN 5 AND THE TAB.
THE CASE OF THE METAL CAN
PACKAGE IS CONNECTED TO PIN 5
(COMMON).
ARROW INDICATES DIRECTION OF
POSITIVE ACCELERATION ALONG AXIS
OF SENSITIVITY.
ADXL05
5
REV. B
Polarity of the Acceleration Output
The polarity of the ADXL05 output is shown in the Figure 1.
When oriented to the earth's gravity (and held in place), the
ADXL05 will experience an acceleration of +1 g. This corre-
sponds to a change of approximately +200 mV at the V
PR
out-
put pin. Note that the polarity will be reversed to a negative
going signal at the buffer amplifier output V
OUT
, due to its
inverting configuration.
+1g
INDICATED POLARITY IS THAT
OCCURRING AT V
PR
.
TAB
PIN 5
+
Figure 1. Output Polarity at V
PR
Acceleration Vectors in Three Dimensions
The ADXL05 is a sensor designed to measure accelerations that
result from an applied force. The ADXL05 responds to the
component of acceleration on its sensitive X axis. Figures 2a
and 2b show the relationship between the sensitive "X" axis and
the transverse "Z" and "Y" axes as they relate to the TO-100
Z
Z
X
TRANSVERSE Z AXIS
SENSITIVE (X) AXIS
SIDE VIEW
X
TAB
PIN 5
Figure 2a. Sensitive X and Transverse Z Axis
TRANSVERSE Y AXIS
TOP VIEW
Y
X
Y
SENSITIVE (X) AXIS
X
TAB
PIN 5
Figure 2b. Sensitive X and Transverse Y Axis
GLOSSARY OF TERMS
Acceleration: Change in velocity per unit time.
Acceleration Vector: Vector describing the net acceleration
acting upon the ADXL05 (A
XYZ
).
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 ADXL05 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 (@ 5 g).
Resonant Frequency: The natural frequency of vibration of
the ADXL05 sensor's central plate (or "beam"). At its resonant
frequency of 12 kHz, the ADXL05's moving center plate has a
peak in its frequency response with a Q of 3 or 4.
Sensitivity: The output voltage change per g unit of accelera-
tion applied, specified at the V
PR
pin in mV/g.
Sensitive Axis (X): The most sensitive axis of the accelerom-
eter sensor. Defined by a line drawn between the package tab
and Pin 5 in the plane of the pin circle. See Figures 2a and 2b.
Sensor Alignment Error: Misalignment between the
ADXL05's on-chip sensor and the package axis, defined by
Pin 5 and the package tab.
Total Alignment Error: Net misalignment of the ADXL05's
on-chip sensor and the measurement axis of the application.
This error includes errors due to sensor die alignment 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 ac-
celeration that appears at the V
PR
output. For example, if the
transverse sensitivity is 1%, then a +10 g transverse acceleration
will cause a 0.1 g signal to appear at V
PR
(1% of 10 g). Trans-
verse sensitivity can result from a sensitivity of the sensor to
transverse forces or from misalignment of the internal sensor to
its package.
Transverse Y Axis: The axis perpendicular (90
) to the pack-
age axis of sensitivity in the plane of the package pin circle. See
Figure 2.
Transverse Z Axis: The axis perpendicular (90
) to both the
package axis of sensitivity and the plane of the package pin
circle. See Figure 2.
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