AD ADXL206

Precision, ±5 g, Dual-Axis,
High Temperature iMEMS Accelerometer
ADXL206
FEATURES
GENERAL DESCRIPTION
High performance, dual-axis accelerometer
on a single IC
−40°C to +175°C ambient temperature range
Long life: guaranteed 1000 hours at TA = 175°C
13 mm × 8 mm × 2 mm side-brazed ceramic dual in-line
package
1 mg resolution at 60 Hz
Low power: 700 μA at VS = 5 V (typical)
High zero g bias repeatability
High sensitivity accuracy
Bandwidth adjustment with a single capacitor
Single-supply operation
RoHS-compliant
Compatible with Sn/Pb and Pb-free solder processes
The ADXL206 is a precision, low power, complete dual-axis
iMEMS® accelerometer for use in high temperature environments. The accelerometer integrates the sensor with signal
conditioned voltage outputs on a single, monolithic IC.
The ADXL206 measures acceleration with a full-scale range
of ±5 g. The ADXL206 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
Capacitors CX and CY at the XOUT and YOUT pins, respectively.
Bandwidths of 0.5 Hz to 2.5 kHz can be selected to suit the
application.
APPLICATIONS
Geological exploration tilt and vibration measurement
Extreme high temperature industrial products
The ADXL206 is available in a 13 mm × 8 mm × 2 mm, 8-lead,
side-brazed ceramic dual in-line package (SBDIP).
FUNCTIONAL BLOCK DIAGRAM
+5V
VS
ADXL206
CDC
AC
AMP
DEMOD
OUTPUT
AMP
OUTPUT
AMP
SENSOR
COM
ST
RFILT
32kΩ
YOUT
XOUT
CY
CX
09600-001
RFILT
32kΩ
Figure 1.
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 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.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2011 Analog Devices, Inc. All rights reserved.
ADXL206
TABLE OF CONTENTS
Features .............................................................................................. 1 Theory of Operation .........................................................................9 Applications ....................................................................................... 1 Performance ...................................................................................9 General Description ......................................................................... 1 Applications Information .............................................................. 10 Functional Block Diagram .............................................................. 1 Power Supply Decoupling ......................................................... 10 Revision History ............................................................................... 2 Setting the Bandwidth Using CX and CY ................................. 10 Specifications..................................................................................... 3 Self-Test ....................................................................................... 10 Absolute Maximum Ratings............................................................ 4 Design Trade-Offs for Selecting Filter Characteristics:
Noise/Bandwidth Trade-Off ........................................................ 10 Thermal Resistance ...................................................................... 4 ESD Caution .................................................................................. 4 Pin Configuration and Function Descriptions ............................. 5 Typical Performance Characteristics ............................................. 6 Using the ADXL206 with Operating Voltages
Other Than 5 V .......................................................................... 11 Using the ADXL206 As a Dual-Axis Tilt Sensor ................... 11 Outline Dimensions ....................................................................... 12 Ordering Guide .......................................................................... 12 REVISION HISTORY
4/11—Revision 0: Initial Version
Rev. 0 | Page 2 of 12
ADXL206
SPECIFICATIONS
TA = −40°C to +175°C, VS = 5 V, CX = 0.1 μF, acceleration = 0 g, unless otherwise noted. 1
Table 1.
Parameter
SENSOR INPUT
Measurement Range 2
Nonlinearity
Package Alignment Error
Alignment Error
Cross-Axis Sensitivity
SENSITIVITY (RATIOMETRIC) 3
Sensitivity at XOUT, YOUT
Sensitivity Change Due to Temperature 4
ZERO g BIAS LEVEL (RATIOMETRIC)
0 g Voltage at XOUT, YOUT
0 g Bias Repeatability
NOISE PERFORMANCE
Noise Density
FREQUENCY RESPONSE 5
CX, CY Range 6
RFILT Tolerance
Sensor Resonant Frequency
SELF-TEST 7
Logic Input Low
Logic Input High
ST Input Resistance to Ground
Output Change at XOUT, YOUT
OUTPUT AMPLIFIER
Output Swing Low
Output Swing High
LIFESPAN
Usable Life Expectancy
POWER SUPPLY
Operating Voltage Range
Supply Current
Turn-On Time 8
Test Conditions/Comments
Each axis
Min
Typ
Max
g
% FS
Degrees
Degrees
%
±5
±0.2
±1
±0.1
±1.5
X sensor to Y sensor
VS = 5 V
VS = 5 V
296
312
±0.3
Unit
328
mV/g
%
VS = 5 V, TA = 25°C
−40°C ≤ TA ≤ +175°C
2.5 ± 0.025
±10
V
mg
VS = 5 V, TA = 25°C
110
μg/√Hz rms
0.002
24
ST pin Logic 0 to Logic 1
No load
4
30
150
0.05
TA = 175°C
32
5.5
50
250
10
40
μF
kΩ
kHz
1
V
V
kΩ
mV
350
0.2
4.5
V
V
1000
Hours
4.75
0.7
20
1
5.25
1.5
V
mA
ms
Minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed.
Guaranteed by measurement of initial offset and sensitivity.
3
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.
4
Defined as the output change from ambient temperature to maximum temperature or from ambient temperature to minimum temperature.
5
Actual frequency response controlled by user-supplied external capacitors (CX, CY).
6
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.
7
Self-test response changes cubically with VS.
8
Larger values of CX, CY increase turn-on time. Turn-on time is approximately 160 × CX or CY + 4 ms, where CX and CY are in microfarads (μF).
2
Rev. 0 | Page 3 of 12
ADXL206
ABSOLUTE MAXIMUM RATINGS
THERMAL RESISTANCE
Table 2.
Parameter
Acceleration (Any Axis)
Unpowered
Powered
VS
All Other Pins
Output Short-Circuit Duration
(Any Pin to Common)
Ambient Operating Temperature
Range (TA)
Storage Temperature Range
θJA is specified for the worst-case conditions, that is, for a device
soldered in a printed circuit board (PCB) for surface-mount
packages.
Rating
500 g
500 g
−0.3 V to +7.0 V
(COM − 0.3 V) to
(VS + 0.3 V)
Indefinite
Table 3. Thermal Resistance
Package Type
8-Lead SBDIP
θJA
120
θJC
20
ESD CAUTION
−55°C to +175°C
−65°C to +200°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.
CRITICAL ZONE
TL TO TP
tP
TP
TL
tL
TSMAX
TSMIN
tS
RAMP-DOWN
PREHEAT
TIME 25°C TO PEAK
TIME
09600-002
TEMPERATURE
RAMP-UP
Figure 2. Recommended Soldering Profile
Table 4. Recommended Soldering Profile Limits
Profile Feature
Average Ramp Rate (TL to TP)
Preheat
Minimum Temperature (TSMIN)
Maximum Temperature (TSMAX)
Time (TSMIN to TSMAX), tS
Ramp-Up Rate (TSMAX to TL)
Time Maintained Above Liquidous (tL)
Liquidous Temperature (TL)
Peak Temperature (TP)
Time Within 5°C of Actual Peak Temperature (tP)
Ramp-Down Rate (TP to TL)
Time 25°C to Peak Temperature
Sn63/Pb37
3°C/sec max
Pb-Free
3°C/sec max
100°C
150°C
60 sec to 120 sec
3°C/sec max
60 sec to 150 sec
183°C
240°C + 0°C/−5°C
10 sec to 30 sec
6°C/sec max
6 minutes max
150°C
200°C
60 sec to 150 sec
3°C/sec max
60 sec to 150 sec
217°C
260°C + 0°C/−5°C
20 sec to 40 sec
6°C/sec max
8 minutes max
Rev. 0 | Page 4 of 12
Unit
°C/W
ADXL206
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
NC
2
COM
3
YOUT
+X
8
ADXL206
7
6
TOP VIEW
4 (Not to Scale) 5
ST
VS2
VS
XOUT
NC = NO CONNECT. DO NOT
CONNECT TO THIS PIN.
09600-003
COM
Figure 3. Pin Configuration
Table 5. Pin Function Descriptions
Pin No.
1, 3
2
4
5
6
7
8
Mnemonic
COM
NC
YOUT
XOUT
VS
VS2
ST
Description
Common.
No Connect. Do not connect to this pin.
Y Channel Output.
X Channel Output.
Supply.
Supply. Must be connected to VS.
Self-Test.
Rev. 0 | Page 5 of 12
ADXL206
TYPICAL PERFORMANCE CHARACTERISTICS
VS = 5 V, unless otherwise noted.
70
60
PERCENT OF POPULATION (%)
50
40
30
20
10
40
30
20
20
20
80
80
70
2.57
09600-007
2.56
2.55
2.54
2.53
2.52
2.51
2.49
2.48
2.47
2.50
1.2
1.0
0.8
0.6
0.2
0
–0.2
0.4
Figure 6. X-Axis Sensitivity at TA = 25°C
Figure 9. Y-Axis Sensitivity at TA = 25°C
Rev. 0 | Page 6 of 12
0.387
09600-009
SENSITIVITY (V/g)
0.377
0.367
0.357
09600-006
0.387
0.377
0.367
0.357
0.347
0.337
0
0.327
0
0.317
10
0.307
10
0.297
–0.4
20
0.347
20
30
0.337
30
40
0.327
40
50
0.317
50
60
0.307
60
0.297
70
0.287
PERCENT OF POPULATION (%)
90
0.287
2.46
TEMPERATURE COEFFICIENT (mg/°C)
Figure 8. Y-Axis Zero g Bias Temperature Coefficient
Figure 5. X-Axis Zero g Bias Temperature Coefficient
PERCENT OF POPULATION (%)
–0.6
0
09600-008
TEMPERATURE COEFFICIENT (mg/°C)
5
09600-005
1.2
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
5
10
–0.8
10
15
–1.0
15
–1.2
PERCENT OF POPULATION (%)
25
–1.2
PERCENT OF POPULATION (%)
Figure 7. Y-Axis Zero g Bias at TA = 25°C
25
SENSITIVITY (V/g)
2.45
VOLTAGE (V)
Figure 4. X-Axis Zero g Bias at TA = 25°C
0
2.44
2.43
2.57
VOLTAGE (V)
0
09600-004
2.56
2.55
2.54
2.53
2.52
2.51
2.50
2.49
2.48
2.47
2.46
2.45
2.44
0
50
10
2.43
PERCENT OF POPULATION (%)
60
40
40
35
35
PERCENT OF POPULATION (%)
30
25
20
15
10
30
25
20
15
10
–4
–3
–2
–1
0
1
2
3
4
5
CROSS-AXIS RESPONSE (%)
0
–5
09600-010
0
–5
–3
–2
–1
0
1
2
3
4
5
CROSS-AXIS RESPONSE (%)
Figure 10. Cross-Axis Response, Z-Axis vs. X-Axis
Figure 13. Cross-Axis Response, Z-Axis vs. Y-Axis
325
325
320
320
SENSITIVITY (mV/g)
SENSITIVITY (mV/g)
–4
09600-011
5
5
315
310
305
315
310
305
–50
0
50
100
AMBIENT TEMPERATURE (°C)
150
200
300
–100
09600-016
300
–100
Figure 11. X-Axis Sensitivity over Temperature, Nine Devices
–50
0
50
100
AMBIENT TEMPERATURE (°C)
150
200
Figure 14. Y-Axis Sensitivity over Temperature, Nine Devices
100
5V
75
25
0
–25
–50
–75
X-AXIS
–100
OUTPUT
VOLTAGE (1V/DIV)
OUTPUT BIAS DRIFT (mV)
INPUT
Y-AXIS
50
0V
–125
–175
–25
0
25
50
75
100 125 150
AMBIENT TEMPERATURE (°C)
175
200
TIME (2ms/DIV)
09600-015
–200
–50
09600-014
–150
Figure 15. Turn-On Time, CX, CY = 0.1 μF, Time Scale = 2 ms/div
Figure 12. Zero g Output Bias Drift over Temperature, Eight Devices
Rev. 0 | Page 7 of 12
09600-017
PERCENT OF POPULATION (%)
ADXL206
ADXL206
20
15
10
5
0
–40
–30
–20
0
–10
10
20
OUTPUT BIAS DRIFT (mV)
10
5
–20
–10
0
10
OUTPUT BIAS DRIFT (mV)
Figure 18. Y-Axis Zero g Output Bias Drift over 1000 Hours
at TA = 175°C, Powered
0.9
100
VS = 5V
VS = 5V
0.8
80
CURRENT (mA)
70
60
50
40
30
20
0.7
0.6
0.5
0.4
0
200
300
400
500
600
700
800
CURRENT (µA)
900
1000
Figure 17. Supply Current at TA = 25°C
0.3
–50
0
50
100
AMBIENT TEMPERATURE (°C)
Figure 19. Supply Current vs. Temperature
Rev. 0 | Page 8 of 12
150
09600-012
10
09600-013
PERCENT OF POPULATION (%)
15
0
Figure 16. X-Axis Zero g Output Bias Drift over 1000 Hours
at TA = 175°C, Powered
90
20
09600-019
PERCENT OF POPULATION (%)
25
09600-018
PERCENT OF POPULATION (%)
25
ADXL206
THEORY OF OPERATION
The ADXL206 is a complete acceleration measurement system
on a single, monolithic IC. The part contains a polysilicon, surfacemicromachined sensor and signal conditioning circuitry to implement an open-loop acceleration measurement architecture. The
output signals are analog voltages proportional to acceleration.
The ADXL206 is capable of measuring both positive and negative
accelerations to at least ±5 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 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.
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 2 mg over the −40°C to +175°C
temperature range).
Figure 12 shows the 0 g output performance of eight parts over
the −40°C to +175°C temperature range.
Figure 11 and Figure 14 show the typical sensitivity shift over
temperature for VS = 5 V. Sensitivity stability is optimized for
VS = 5 V, but it is very good over the full supply voltage range.
Rev. 0 | Page 9 of 12
ADXL206
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. In
some cases, however, 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 ADXL206
output. If additional decoupling is needed, a 100 Ω (or smaller)
resistor or ferrite bead can be inserted in the supply line of the
ADXL206. Additionally, a larger bulk bypass capacitor (in the
1 μF to 22 μF range) can be added in parallel to CDC.
SETTING THE BANDWIDTH USING CX AND CY
The ADXL206 has provisions for band-limiting the XOUT and
YOUT pins. A capacitor must be added to the pin to implement
low-pass filtering for antialiasing and noise reduction. The
equation for the 3 dB bandwidth is
f−3 dB = 1/(2π(32 kΩ) × Cx)
or more simply,
f−3 dB = 5 μF/Cx
The tolerance of the internal resistor (RFILT) can vary typically
as much as ±25% of its nominal value (32 kΩ); thus, the bandwidth varies accordingly. A minimum capacitance of 2000 pF
for CX and CY is required in all cases.
The output of the ADXL206 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 ADXL206 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). The user should 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 ADXL206 is determined by
(
) (
BW × 1.6
) (
100 × 1.6 = 1.4 mg
rms Noise = 110 μg / Hz ×
(
rms Noise = 110 μg / Hz ×
Capacitor (μF)
4.7
0.47
0.10
0.05
0.027
0.01
)
)
Often, the peak value of the noise is desired. Peak-to-peak noise
can only be estimated by statistical methods. Table 7 is useful
for estimating the probability of exceeding various peak values,
given the rms value.
Table 7. Estimation of Peak-to-Peak Noise
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 whether the accelerometer is functional. The typical change
in output is 800 mg (corresponding to 250 mV). This pin can be
left open-circuit or connected to common in normal use.
The ST pin should never be exposed to voltage greater than
VS + 0.3 V. If the system design is such that this condition
cannot be guaranteed (that is, multiple supply voltages are
present), it is recommended that a clamping diode with low
forward voltage be connected between ST and VS.
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 XOUT.
At 100 Hz, the noise is
Table 6. Filter Capacitor Selection, CX and CY
Bandwidth (Hz)
1
10
50
100
200
500
DESIGN TRADE-OFFS FOR SELECTING FILTER
CHARACTERISTICS: NOISE/BANDWIDTH TRADE-OFF
Peak-to-Peak Value
2 × rms
4 × rms
6 × rms
8 × rms
% of Time That Noise Exceeds
Nominal Peak-to-Peak Value
32
4.6
0.27
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 8 gives the typical noise output of the ADXL206
for various CX and CY values.
Table 8. Typical Noise Output for Various Capacitor Values
Bandwidth (Hz)
10
50
100
500
Rev. 0 | Page 10 of 12
CX, CY
(μF)
0.47
0.1
0.047
0.01
RMS Noise
(mg)
0.4
1.0
1.4
3.1
Peak-to-Peak Noise
Estimate (mg)
2.6
6
8.4
18.7
ADXL206
USING THE ADXL206 WITH OPERATING VOLTAGES
OTHER THAN 5 V
USING THE ADXL206 AS A DUAL-AXIS TILT
SENSOR
The ADXL206 is tested and specified at VS = 5 V; however, it
can be powered with VS as low as 3 V or as high as 6 V. Some
performance parameters change as the supply voltage is varied.
One of the most popular applications of the ADXL206 is tilt
measurement. An accelerometer uses the force of gravity as an
input vector to determine the orientation of an object in space.
The ADXL206 output is ratiometric; therefore, the output
sensitivity (or scale factor) varies proportionally to the supply
voltage. The zero g bias output is also ratiometric; therefore, the
zero g output is nominally equal to VS/2 at all supply voltages.
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, the sensitivity of the accelerometer to changes in tilt is highest. When the axis of sensitivity
is parallel 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.
The output noise is not ratiometric but is absolute in volts;
therefore, the noise density decreases as the supply voltage
increases.
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. Therefore, at VS = 3 V, the typical self-test response is approximately
50 mV or about 160 mg.
Dual-Axis Tilt Sensor: Converting Acceleration to Tilt
When the accelerometer is oriented so that 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. After the output signal
from the accelerometer is converted to an acceleration that varies
between −1 g and +1 g, the output tilt in degrees is calculated
as follows:
PITCH = arcsin(AX/1 g)
ROLL = arcsin(AY/1 g)
Make sure to account for overranges. It is possible for the
accelerometer to output a signal greater than ±1 g due to
vibration, shock, or other accelerations.
Rev. 0 | Page 11 of 12
ADXL206
OUTLINE DIMENSIONS
0.528
0.520
0.512
8
5
1
INDEX
MARK
0.298
0.290
0.282
4
0.305
0.300
0.295
0.125
0.110
0.095
0.011
0.010
0.009
0.130 NOM
SEATING
PLANE
0.054
NOM
0.175 NOM
0.105
0.100
0.095
0.032
NOM
0.045
0.035
0.025
0.020
0.018
0.016
0.310
0.300
0.290
0.011
0.010
0.009
07-08-2010-B
0.105
0.095
0.085
0.320
0.310
0.300
Figure 20. 8-Lead Side-Brazed Ceramic Dual In-Line Package [SBDIP]
(D-8-1)
Dimensions shown in inches
ORDERING GUIDE
Model 1, 2
ADXL206HDZ
1
2
Number of Axes
2
Specified Voltage (V)
5
Temperature Range
−40°C to +175°C
Lead finish. Gold over nickel over tungsten.
Z = RoHS Compliant Part.
©2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D09600-0-4/11(0)
Rev. 0 | Page 12 of 12
Package Description
8-Lead SBDIP
Package Option
D-8-1