ADW22279ZC-RL7 [ADI]
Single-Axis, High-g, iMEMS ccelerometers; 单轴，高g ，公司的iMEMS ccelerometers
| 型号： | ADW22279ZC-RL7 |
| 厂家： | 
ADI |
| 描述： | Single-Axis, High-g, iMEMS ccelerometers |
| 文件： | 总12页 (文件大小：171K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Single-Axis, High-g,
iMEMS® Accelerometers
ADXL78
FEATURES
GENERAL DESCRIPTION
Complete acceleration measurement system on a single
monolithic IC
Available in 35 g, 50 g, or 70 g output full-scale ranges
Full differential sensor and circuitry for high resistance
to EMI/RFI
Environmentally robust packaging
Complete mechanical and electrical self-test on
digital command
The ADXL78 is a low power, complete single-axis accelerometer
with signal conditioned voltage outputs that are on a single
monolithic IC. This product measures acceleration with a full-
scale range of ±±3 g, ±35 g, or ±75 g (minimum). It can also
measure both dynamic acceleration (vibration) and static
acceleration (gravity).
The ADXL78 is the fourth-generation surface micromachined
iMEMS® accelerometer from ADI with enhanced performance
and lower cost. Designed for use in front and side impact airbag
applications, this product also provides a complete cost-
Output ratiometric to supply
Sensitive axes in the plane of the chip
High linearity (0.2% of full scale)
Frequency response down to dc
effective solution useful for a wide variety of other applications.
The ADXL78 is temperature stable and accurate over the
automotive temperature range, with a self-test feature that fully
exercises all the mechanical and electrical elements of the
sensor with a digital signal applied to a single pin.
Low noise
Low power consumption (1.3 mA)
Tight sensitivity tolerance and 0 g offset capability
Largest available prefilter clipping headroom
400 Hz, 2-pole Bessel filter
Single-supply operation
Compatible with Sn/Pb and Pb-free solder processes
Qualified for automotive applications
The ADXL78 is available in a 3 mm × 3 mm × 2 mm,
8-terminal ceramic LCC package.
APPLICATIONS
Vibration monitoring and control
Vehicle collision sensing
Shock detection
FUNCTIONAL BLOCK DIAGRAM
V
S
ADXL78
TIMING
GENERATOR
V
DD
V
DD2
400Hz
BESSEL
FILTER
DIFFERENTIAL
DEMOD
AMP
X
EXC
OUT
SENSOR
SELF-TEST
Figure 1.
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 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 registeredtrademarks arethe property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
www.analog.com
©2010 Analog Devices, Inc. All rights reserved.
ADXL78
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications........................................................................................8
Power Supply Decoupling ............................................................8
Self-Test ..........................................................................................8
Clock Frequency Supply Response .............................................8
Signal Distortion ...........................................................................8
Outline Dimensions..........................................................................9
ADXL78 Ordering Guide.............................................................9
Automotive Products....................................................................9
Applications....................................................................................... 1
General Description......................................................................... 1
Functional Block Diagram .............................................................. 1
Specifications..................................................................................... ±
Absolute Maximum Ratings............................................................ 4
ESD Caution.................................................................................. 4
Pin Configuration and Function Descriptions............................. 3
Theory of Operation ........................................................................ 7
REVISION HISTORY
7/10—Rev. A to Rev. B
Updated Format .................................................................Universal
Change to Features Section ............................................................. 1
Updated Outline Dimensions......................................................... 9
Changes to Ordering Guide ............................................................ 9
Added Automotive Products Section ............................................ 9
5/05—Rev. 0 to Rev. A
Rev. B | Page 2 of 12
ADXL78
SPECIFICATIONS1
At TA = −45°C to +153°C, 3.5 V dc ± 3ꢀ, acceleration = 5 g, unless otherwise noted.
Table 1.
Model No. AD22279
Model No. AD22280
Model No. AD22281
Parameter
Conditions
1ꢀꢀ ꢁμ
Min
Typ Max
Min
Typ Max
Min
Typ Max
Unit
SENSOR
Output Full-Scale Range IOUT
Nonlinearity
Package μlignment Error
Cross-μxis Sensitivity
Resonant Frequency
Sensitivity, Ratiometric
(Over Temperature)
≤
37
55
7ꢀ
g
%
Degree
%
kHz
mV/g
ꢀ.2
1
2
ꢀ.2
1
2
ꢀ.2
1
2
−5
+5
−5
+5
39.9
−5
+5
24
24
38
24
VDD = 5 V, 1ꢀꢀ Hz 52.25 55
57.75
36.1
25.65 27
28.35
OFFSET
Zero-g Output Voltage
VOUT − VDD/2,
VDD = 5 V
−2ꢀꢀ
+2ꢀꢀ
3
−15ꢀ
+15ꢀ
3
−15ꢀ
+15ꢀ
3.5
mV
(Over Temperature)2
NOISE
Noise Density
1ꢀ Hz − 4ꢀꢀ Hz,
5 V
1.1
5
1.4
5
1.8
5
mg/√Hz
Clock Noise
mV p-p
FREQUENCY RESPONSE
−3 dB Frequency
−3 dB Frequency Drift
2-pole Bessel
36ꢀ
4ꢀꢀ 44ꢀ
2
36ꢀ
4ꢀꢀ 44ꢀ
2
36ꢀ
4ꢀꢀ 44ꢀ
2
Hz
Hz
25°C to
TMIN or TMμX
SELF-TEST
Output Change
V
DD = 5 V
44ꢀ
3.5
55ꢀ 66ꢀ
3ꢀ4
3.5
38ꢀ 456
216
3.5
27ꢀ 324
mV
3
(Cube vs. VDD
)
Logic Input High
Logic Input Low
Input Resistance
VDD = 5 V
VDD = 5 V
Pull-down
V
V
kΩ
1
1
1
3ꢀ
5ꢀ
3ꢀ
5ꢀ
3ꢀ
5ꢀ
resistor to GND
OUTPUT μMPLIFIER
Output Voltage Swing
Capacitive Load Drive
PREFILTER HEμDROOM
CFSR @ 4ꢀꢀ kHz
IOUT
=
4ꢀꢀ ꢁμ
ꢀ.25
1ꢀꢀꢀ
VDD − ꢀ.25 ꢀ.25
1ꢀꢀꢀ
VDD − ꢀ.25 ꢀ.25
1ꢀꢀꢀ
VDD − ꢀ.25
V
pF
g
28ꢀ
5
4ꢀꢀ
4
56ꢀ
3
V/V
V
V
POWER SUPPLY (VDD
)
4.75
3.5
5.25
6
4.75
3.5
5.25
6
4.75
3.5
5.25
6
Functional Range
Quiescent Supply Current VDD = 5 V
TEMPERμTURE RμNGE
1.3
2
1.3
2
1.3
2
mμ
°C
−4ꢀ
+1ꢀ5
−4ꢀ
+1ꢀ5
−4ꢀ
+1ꢀ5
1 μll minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed.
2 Zero g output is ratiometric.
3 Self-test output at VDD = (Self-Test Output at 5 V) × (VDD/5 V)3.
Rev. B | Page 3 of 12
ADXL78
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
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.
Rating
μcceleration (μny μxis, Unpowered)
μcceleration (μny μxis, Powered)
VS
4ꢀꢀꢀ g
4ꢀꢀꢀ g
−ꢀ.3 V to +7.ꢀ V
(COM − ꢀ.3 V) to
(VS + ꢀ.3 V)
μll Other Pins
Output Short-Circuit Duration
(μny Pin to Common)
Operating Temperature Range
Storage Temperature
Indefinite
ESD CAUTION
−65°C to +15ꢀ°C
−65°C to +15ꢀ°C
Rev. B | Page 4 of 12
ADXL78
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
V
DD2
8
NC
NC
1
2
3
7
6
5
V
X
DD
ADXL78
TOP VIEW
OUT
(Not to Scale)
COM
NC
4
ST
NC = NO CONNECT
Figure 2. Pin Configuration
Table 3. Pin Function Descriptions
Pin No.
Mnemonic
Description
1
2
3
4
5
6
7
8
NC
NC
COM
ST
NC
XOUT
VDD
VDD2
Do Not Connect
Do Not Connect
Common
Self-Test
Do Not Connect
X Channel Output
3.5 V to 6 V
3.5 V to 6 V
Rev. B | Page 5 of 12
ADXL78
CRITICAL ZONE
TO T
tP
T
L
P
T
P
RAMP-UP
T
L
tL
T
SMAX
T
SMIN
tS
RAMP-DOWN
PREHEAT
t25°C TO PEAK
TIME
Figure 3. Recommended Soldering Profile
Table 4. Recommended Soldering Profile
Profile Feature
Sn63/Pb37
Pb-Free
μVERμGE RμMP RμTE (TL TO TP)
PREHEμT
3°C/s max
3°C/s max
Minimum Temperature (TSMIN
)
1ꢀꢀ°C
15ꢀ°C
Maximum Temperature (TSMμX
TIME (TSMIN TO TSMμX), tS
TSMμX TO TL
)
15ꢀ°C
2ꢀꢀ°C
6ꢀ s − 12ꢀ s
6ꢀ s − 15ꢀ s
Ramp-Up Rate
3°C/s
3°C/s
TIME MμINTμINED μBOVE LIQUIDOUS (TL)
Liquidous Temperature (TL)
Time (tL)
183°C
6ꢀ s − 15ꢀ s
217°C
6ꢀ s − 15ꢀ s
26ꢀ°C + ꢀ°C/−5°C
2ꢀ s − 4ꢀ s
6°C/s max
8 min max
PEμK TEMPERμTURE (TP)
24ꢀ°C + ꢀ°C/−5°C
1ꢀ s − 3ꢀ s
TIME WITHIN 5°C OF μCTUμL PEμK TEMPERμTURE (tP)
RμMP-DOWN RμTE
TIME 25°C TO PEμK TEMPERμTURE
6°C/s max
6 min max
PIN 8
XXXXX
XXXX
X
= 2.462V
OUT
22280
X
= 2.500V
X
= 2.500V
OUT
OUT
2 2 2 8 0
X X X X
X
= 2.538V
OUT
X X X X X
X
= 2.500V
OUT
EARTH'S SURFACE
Figure 4. Output Response vs. Orientation
Rev. B | Page 6 of 12
ADXL78
THEORY OF OPERATION
The ADXL78 provides a fully differential sensor structure and
circuit path, resulting in the industry’s highest resistance to
EMI/RFI effects. This latest generation uses electrical feedback
with zero-force feedback for improved accuracy and stability.
The sensor resonant frequency is significantly higher than the
signal bandwidth set by the on-chip filter, avoiding the signal
analysis problems caused by resonant peaks near the signal
bandwidth.
ANCHOR
MOVABLE
FRAME
PLATE
CAPACITORS
UNIT
SENSING
CELL
FIXED
PLATES
UNIT
FORCING
CELL
MOVING
PLATE
Figure 3 is a simplified view of one of the differential sensor
elements. Each sensor includes several differential capacitor
unit cells. Each cell is composed of fixed plates attached
to the substrate and movable plates attached to the frame.
Displacement of the frame changes the differential capacitance,
which is measured by the on-chip circuitry.
ANCHOR
Figure 5. Simplified View of Sensor Under Acceleration
Complementary 455 kHz square waves drive the fixed plates.
Electrical feedback adjusts the amplitudes of the square waves
such that the ac signal on the moving plates is 5. The feedback
signal is linearly proportional to the applied acceleration. This
unique feedback technique ensures that there is no net
electrostatic force applied to the sensor. The differential
feedback control signal is also applied to the input of the filter,
where it is filtered and converted to a single-ended signal.
Rev. B | Page 7 of 12
ADXL78
APPLICATIONS
If the difference frequency is outside of the signal bandwidth,
the filter attenuates it. However, both the power supply clock
and the accelerometer clock may vary with time or temperature,
which can cause the interference signal to appear in the output
filter bandwidth.
POWER SUPPLY DECOUPLING
For most applications, a single 5.1 μF capacitor, CDC, adequately
decouples the accelerometer from noise on the power supply.
However, in some cases, particularly where noise is present at
the 455 kHz internal clock frequency (or any harmonic
The ADXL78 addresses this issue in two ways. First, the high
clock frequency eases the task of choosing a power supply clock
frequency such that the difference between it and the accelero-
meter clock remains well outside of the filter bandwidth.
Second, the ADXL78 is the only micromachined accelerometer
to have a fully differential signal path, including differential
sensors. The differential sensors eliminate most of the power
supply noise before it reaches the demodulator. Good high
frequency supply bypassing, such as a ceramic capacitor close to
the supply pins, also minimizes the amount of interference.
thereof), noise on the supply can cause interference on the
ADXL78’s output. If additional decoupling is needed, a 35 Ω (or
smaller) resistor or ferrite bead can be inserted in the supply
line. Additionally, a larger bulk bypass capacitor (in the 1 μF to
4.7 μF range) can be added in parallel to CDC
.
SELF-TEST
The fixed fingers in the forcing cells are normally kept at the
same potential as that of the movable frame. When the self-test
digital input is activated, the voltage on the fixed fingers on one
side of the moving plate in the forcing cells is changed. This
creates an attractive electrostatic force, which causes the frame
to move toward those fixed fingers. The entire signal channel is
active; therefore, the sensor displacement causes a change in
The clock frequency supply response (CFSR) is the ratio of the
response at VOUT to the noise on the power supply near the
accelerometer clock frequency. A CFSR of ± means that the
signal at VOUT is ±× the amplitude of an excitation signal at VDD
near the accelerometer internal clock frequency. This is
analogous to the power supply response, except that the
stimulus and the response are at different frequencies. The
ADXL78’s CFSR is 15× better than a typical single-ended
accelerometer system.
VOUT. The ADXL78 self-test function is a comprehensive
method of verifying the operation of the accelerometer.
Because electrostatic force is independent of the polarity of the
voltage across capacitor plates, a positive voltage is applied in
half of the forcing cells, and its complement in the other half of
the forcing cells. Activating self-test causes a step function force
to be applied to the sensor, while the capacitive coupling term is
canceled. The ADXL78 has improved self-test functionality,
including excellent transient response and high speed switching
capabilities. Arbitrary force waveforms can be applied to the
sensor by modulating the self-test input, such as test signals to
measure the system frequency response or even crash signals to
verify algorithms within the limits of the self-test swing.
SIGNAL DISTORTION
Signals from crashes and other events may contain high
amplitude, high frequency components. These components
contain very little useful information and are reduced by the
2-pole Bessel filter at the output of the accelerometer. However,
if the signal saturates at any point, the accelerometer output
does not look like a filtered version of the acceleration signal.
The signal may saturate anywhere before the filter. For example,
if the resonant frequency of the sensor is low, the displacement
per unit acceleration is high. The sensor may reach the
mechanical limit of travel if the applied acceleration is high
enough. This can be remedied by locating the accelerometer
where it does not see high values of acceleration, and by using a
higher resonant frequency sensor such as the ADXL78.
The ST pin should never be exposed to voltages greater than
VS + 5.± V. If this cannot be guaranteed due to the system
design (for instance, if there are multiple supply voltages), then
a low VF clamping diode between ST and VS is recommended.
CLOCK FREQUENCY SUPPLY RESPONSE
In any clocked system, power supply noise near the clock
frequency may have consequences at other frequencies. An
internal clock typically controls the sensor excitation and the
signal demodulator for micromachined accelerometers.
Also, the electronics may saturate in an overload condition
between the sensor output and the filter input. Ensuring that
the internal circuit nodes operate linearly to at least several
times the full-scale acceleration value can minimize electrical
saturation. The ADXL78’s circuits are linear to approximately
8× full scale.
If the power supply contains high frequency spikes, they may be
demodulated and interpreted as an acceleration signal. A signal
appears as the difference between the noise frequency and the
demodulator frequency. If the power supply spikes are 155 Hz
away from the demodulator clock, there is an output term at
155 Hz. If the power supply clock is at exactly the same frequency
as the accelerometer clock, the term appears as an offset.
Rev. B | Page 8 of 12
ADXL78
OUTLINE DIMENSIONS
0.030
0.025
0.020
(PLATING OPTION 1,
SEE DETAIL A
FOR OPTION 2)
0.087
0.078
0.069
0.028
0.020 DIA
0.012
0.203
0.197 SQ
0.193
0.054
0.050
0.046
0.020
0.015
0.010
(R 4 PLCS)
1
3
7
5
0.180
0.177 SQ
0.174
0.106
0.100
0.094
0.075 REF
R 0.008
(8 PLCS)
0.008
0.006
0.004
TOP VIEW
BOTTOM VIEW
R 0.008
(4 PLCS)
0.077
0.070
0.063
0.019 SQ
DETAIL A
(OPTION 2)
Figure 6. 8-Terminal Ceramic Leadless Chip Carrier [LCC]
(E-8-1)
Dimensions shown in inches
ADXL78 ORDERING GUIDE
Parts
per
Reel
Measurement Specified
Temperature
Voltage (V) Range
Package
Option
Model1, 2, 3
Range
35 g
35 g
35 g
35 g
5ꢀ g
5ꢀ g
5ꢀ g
5ꢀ g
7ꢀ g
7ꢀ g
7ꢀ g
7ꢀ g
Package Description
μD22279-μ-R2
μD22279-μ
μDW22279ZC
25ꢀ
3,ꢀꢀꢀ
3,ꢀꢀꢀ
5
5
5
5
5
5
5
5
5
5
5
5
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
−4ꢀ°C to +1ꢀ5°C 8-Terminal Ceramic Leadless Chip Carrier
E-8-1
E-8-1
E-8-1
E-8-1
E-8-1
E-8-1
E-8-1
E-8-1
E-8-1
E-8-1
E-8-1
E-8-1
μDW22279ZC-RL7 25ꢀ
μD2228ꢀ-R2
μD2228ꢀ
μDW2228ꢀZC
25ꢀ
3,ꢀꢀꢀ
3,ꢀꢀꢀ
μDW2228ꢀZC-RL7 25ꢀ
μD22281-R2
μD22281
μDW22281ZC
25ꢀ
3,ꢀꢀꢀ
3,ꢀꢀꢀ
μDW22281ZC-RL7 25ꢀ
1 μll models are on tape and reel and are RoHS compliant parts.
2 Z = RoHS Compliant Part.
3 W = Qualified for μutomotive μpplications.
AUTOMOTIVE PRODUCTS
The ADW22279, ADW22285, and ADW22281 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 Automotive
Reliability reports for these models.
Rev. B | Page 9 of 12
ADXL78
NOTES
Rev. B | Page 1ꢀ of 12
ADXL78
NOTES
Rev. B | Page 11 of 12
ADXL78
NOTES
©2010 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05368-0-7/10(B)
Rev. B | Page 12 of 12
相关型号：
ADW22282ZD-RL7
IC SPECIALTY ANALOG CIRCUIT, CQCC8, 5 X 5 MM, 2 MM HEIGHT, ROHS COMPLIANT, CERAMIC, LCC-8, Analog IC:Other
ADI
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