概述
数据手册AD22284-A-R2 概述
Dual-Axis, High-g, MEMS Accelerometers 双轴，高g ， MEMS加速度计
AD22284-A-R2 数据手册
通过下载AD22284-A-R2数据手册来全面了解它。这个PDF文档包含了所有必要的细节，如产品概述、功能特性、引脚定义、引脚排列图等信息。
PDF下载Dual-Axis, High-g,
iMEMS® Accelerometers
ADXL278
FEATURES
GENERAL DESCRIPTION
Complete dual-axis acceleration measurement system on
a single monolithic IC
Available in 35 g/ 35 g, 50 g/ 50 g, or 70 g/ 35 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 ADXL278 is a low power, complete, dual-axis
accelerometer with signal conditioned voltage outputs that are
on a single monolithic IC. This product measures acceleration
with a full-scale range of (X-axis/Y-axis) ±±3 g/±±3 g, ±35 g/
±35 g, or ±75 g/±±3 g (minimum). The ADXL278 can also
measure both dynamic acceleration (vibration) and static
acceleration (gravity).
The ADXL278 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
Low noise
effective solution useful for a wide variety of other applications.
The ADXL278 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 power consumption
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
The ADXL278 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
ADXL278
400Hz
BESSEL
FILTER
DIFFERENTIAL
SENSOR
DEMOD
AMP
X
EXC
OUT
V
S
V
DD
V
TIMING
GENERATOR
DD2
DD3
V
400Hz
BESSEL
FILTER
DIFFERENTIAL
SENSOR
DEMOD
AMP
Y
EXC
OUT
SELF-TEST
Figure 1.
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 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
Fax: 781.461.3113
www.analog.com
©2005 Analog Devices, Inc. All rights reserved.
ADXL278
TABLE OF CONTENTS
Specifications..................................................................................... ±
Power Supply Decoupling ............................................................8
Self-Test ..........................................................................................8
Clock Frequency Supply Response .............................................8
Signal Distortion ...........................................................................8
Outline Dimensions..........................................................................9
Ordering Guide .............................................................................9
Absolute Maximum Ratings............................................................ 4
ESD Caution.................................................................................. 4
Pin Configuration and Function Descriptions............................. 3
Theory of Operation ........................................................................ 7
Applications....................................................................................... 8
REVISION HISTORY
5/05—Rev. 0 to Rev. A
Rev. A | Page 2 of 12
ADXL278
SPECIFICATIONS1
At TA = −45°C to +153°C, 3.5 V dc ± 3ꢀ, acceleration = 5 g, unless otherwise noted.
Table 1.
Model No. AD22284 Model No. AD22285
Model No. AD22286
Axis Min Typ Max
Parameter
Conditions
Min
Typ Max
Min
Typ Max
Unit
SENSOR
Output Full-Scale Range
IOUT ≤ 1ꢀꢀ ꢁA
37
55
X
Y
7ꢀ
37
g
g
Nonlinearity
Package Alignment Error
Sensor-to-Sensor
Alignment Error
ꢀ.2
1
ꢀ.1
2
ꢀ.2
1
ꢀ.1
2
ꢀ.2
1
ꢀ.1
2
%
Degree
Degree
Cross-Axis Sensitivity
Resonant Frequency
Sensitivity, Ratiometric
(Over Temperature)
−5
+5
−5
+5
−5
+5
%
kHz
24
24
38
24
VDD = 5 V,
1ꢀꢀ Hz
52.25 55
57.75 36.1
39.9
X
Y
25.65 27
28.35 mV/g
52.25 55
57.75 mV/g
OFFSET
Zero-g Output Voltage
VOUT − VDD/2,
VDD = 5 V
−15ꢀ
+15ꢀ
3
−15ꢀ
+15ꢀ
3
X
Y
−1ꢀꢀ
−15ꢀ
+1ꢀꢀ mV
+15ꢀ mV
(Over Temperature)2
NOISE
Noise Density
1ꢀ Hz − 4ꢀꢀ Hz,
5 V
1.1
5
1.4
5
X
Y
1.8
3.5
3
mg/√Hz
1.1
5
mg/√Hz
Clock Noise
mV p-p
FREQUENCY RESPONSE
−3 dB Frequency
−3 dB Frequency Drift
2-pole Bessel
36ꢀ
44ꢀ
4ꢀꢀ 44ꢀ
2
36ꢀ
3ꢀ4
4ꢀꢀ
2
44ꢀ
456
1
36ꢀ
216
4ꢀꢀ 44ꢀ
2
Hz
Hz
25°C to
TMIN or TMAX
SELF-TEST
Output Change
(Cube vs. VDD)3
VDD = 5 V
55ꢀ 66ꢀ
38ꢀ
5ꢀ
X
Y
27ꢀ 324
55ꢀ 66ꢀ
mV
44ꢀ
3.5
mV
V
V
Logic Input High
Logic Input Low
Input Resistance
VDD = 5 V
VDD = 5 V
Pull-down
3.5
3ꢀ
3.5
3ꢀ
1
1
5ꢀ
3ꢀ
5ꢀ
kΩ
resistor to GND
OUTPUT AMPLIFIER
Output Voltage Swing
IOUT = 4ꢀꢀ ꢁA ꢀ.25
1ꢀꢀꢀ
VDD
ꢀ.25
−
ꢀ.25
VDD
ꢀ.25
−
ꢀ.25
VDD
ꢀ.25
−
V
Capacitive Load Drive
PREFILTER HEADROOM
CFSR @ 4ꢀꢀ kHz
1ꢀꢀꢀ
1ꢀꢀꢀ
pF
g
28ꢀ
6
4ꢀꢀ
4.5
56ꢀ
3
6
V/V
V/V
V
POWER SUPPLY (VDD)
Functional Range
4.75
3.5
5.25
6
4.75
3.5
5.25
6
4.75
3.5
5.25
6
V
Quiescent Supply Current
TEMPERATURE RANGE
VDD = 5 V
2.2
2.9
2.2
2.9
2.2
2.9
mA
−4ꢀ
+1ꢀ5
−4ꢀ
+1ꢀ5
−4ꢀ
+1ꢀ5 °C
1 All 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. A | Page 3 of 12
ADXL278
ABSOLUTE MAXIMUM RATINGS
Table 2.
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.
Parameter
Rating
Acceleration (Any Axis, Unpowered)
Acceleration (Any Axis, Powered)
VS
4,ꢀꢀꢀ g
4,ꢀꢀꢀ g
−ꢀ.3 V to +7.ꢀ V
(COM − ꢀ.3 V) to
(VS + ꢀ.3 V)
All Other Pins
Output Short-Circuit Duration
(Any Pin to Common)
Indefinite
Operating Temperature Range
Storage Temperature
−65°C to +15ꢀ°C
−65°C to +15ꢀ°C
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4ꢀꢀꢀ V readily accumulate on the
human body and test equipment and can discharge without detection. Although this product 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.
Rev. A | Page 4 of 12
ADXL278
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
V
DD2
8
V
1
2
3
7
6
5
V
X
DD3
DD
ADXL278
Y
OUT
OUT
TOP VIEW
(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
VDD3
YOUT
COM
ST
NC
XOUT
VDD
3.5 V to 6 V
Y Channel Output
Common
Self-Test
Do Not Connect
X Channel Output
3.5 V to 6 V
VDD2
3.5 V to 6 V
Rev. A | Page 5 of 12
ADXL278
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
AVERAGE RAMP RATE (TL TO TP)
PREHEAT
3°C/s max
3°C/s max
Minimum Temperature (TSMIN
)
1ꢀꢀ°C
15ꢀ°C
Maximum Temperature (TSMAX
TIME (TSMIN TO TSMAX), tS
TSMAX TO TL
)
15ꢀ°C
2ꢀꢀ°C
6ꢀ s − 12ꢀ s
6ꢀ s − 15ꢀ s
Ramp-Up Rate
3°C/s
3°C/s
TIME MAINTAINED ABOVE 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
PEAK TEMPERATURE (TP)
24ꢀ°C + ꢀ°C/−5°C
1ꢀ s − 3ꢀ s
TIME WITHIN 5°C OF ACTUAL PEAK TEMPERATURE (tP)
RAMP-DOWN RATE
6°C/s max
TIME 25°C TO PEAK TEMPERATURE
6 min max
PIN 8
XXXXX
XXXX
X
Y
= 2.462V
OUT
OUT
= 2.500V
22285
X
Y
= 2.500V
= 2.538V
X
Y
= 2.500V
= 2.462V
OUT
OUT
OUT
OUT
2 2 2 8 5
X
= 2.538V
= 2.500V
OUT
X X X X
X X X X X
Y
OUT
X
Y
= 2.500V
= 2.500V
OUT
OUT
EARTH'S SURFACE
Figure 4. Output Response vs. Orientation
Rev. A | Page 6 of 12
ADXL278
THEORY OF OPERATION
The ADXL278 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 255 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. A | Page 7 of 12
ADXL278
APPLICATIONS
POWER SUPPLY DECOUPLING
155 Hz. If the power supply clock is at exactly the same frequency
as the accelerometer clock, the term appears as an offset.
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 255 kHz internal clock frequency (or any harmonic
thereof), noise on the supply can cause interference on the
ADXL278’s output. If additional decoupling is needed, a 35 Ω
(or smaller) resistor or ferrite bead cany be inserted in the
supply line. Additionally, a larger bulk bypass capacitor (in the
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.
The ADXL278 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 ADXL278 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.
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 towards 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
ADXL278’s CFSR is 15× better than a typical single-ended
accelerometer system.
VOUT. The ADXL278’s 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 ADXL278 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 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.
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 ADXL278.
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
internal circuit nodes operate linearly to at least several times
the full-scale acceleration value can minimize electrical
saturation. The ADXL278 circuit is 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
Rev. A | Page 8 of 12
ADXL278
OUTLINE DIMENSIONS
1.27
7
5.00
SQ
0.50 DIAMETER
1.78
1
3
1.27
1.90
2.50
4.50
SQ
TOP VIEW
R 0.38
0.64
2.50
1.27
5
0.20
0.38 DIAMETER
BOTTOM VIEW
R 0.20
Figure 6. 8-Terminal Ceramic Leadless Chip Carrier [LCC]
(E-8)
Dimensions shown in millimeters
AXL278 ORDERING GUIDE
Parts
Measurement
Range
Specified
Voltage (V)
Temperature
Range
Package
Option
Model1
per Reel
Package Description
AD22284-A-R2
AD22284-A
AD22285-R2
AD22285
AD22286-R2
AD22286
25ꢀ
3ꢀꢀꢀ
25ꢀ
3ꢀꢀꢀ
25ꢀ
3ꢀꢀꢀ
35 g/ 35 g
35 g/ 35 g
5ꢀ g/ 5ꢀ g
5ꢀ g/ 5ꢀ g
7ꢀ g/ 35 g
7ꢀ g/ 35 g
5
5
5
5
5
5
−4ꢀ°C to +1ꢀ5°C
−4ꢀ°C to +1ꢀ5°C
−4ꢀ°C to +1ꢀ5°C
−4ꢀ°C to +1ꢀ5°C
−4ꢀ°C to +1ꢀ5°C
−4ꢀ°C to +1ꢀ5°C
8-Lead Ceramic Leadless Chip Carrier
8-Lead Ceramic Leadless Chip Carrier
8-Lead Ceramic Leadless Chip Carrier
8-Lead Ceramic Leadless Chip Carrier
8-Lead Ceramic Leadless Chip Carrier
8-Lead Ceramic Leadless Chip Carrier
E-8
E-8
E-8
E-8
E-8
E-8
1 All models are on tape and reel and are Pb-free parts.
Rev. A | Page 9 of 12
ADXL278
NOTES
Rev. A | Page 1ꢀ of 12
ADXL278
NOTES
Rev. A | Page 11 of 12
ADXL278
NOTES
©2005 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D05365–0–5/05(A)
Rev. A | Page 12 of 12
AD22284-A-R2 CAD模型
引脚图
封装焊盘图
AD22284-A-R2 相关器件
| 型号 | 制造商 | 描述 | 价格 | 文档 |
| AD22285 | ADI | Dual-Axis, High-g, MEMS Accelerometers | 获取价格 |
|
| AD22285-R2 | ADI | Dual-Axis, High-g, MEMS Accelerometers | 获取价格 |
|
| AD22286 | ADI | Dual-Axis, High-g, MEMS Accelerometers | 获取价格 |
|
| AD22286-R2 | ADI | Dual-Axis, High-g, MEMS Accelerometers | 获取价格 |
|
| AD22293Z | ADI | Precision ±1.7 g, ±5 g, ±18 g Single-/ Dual-Axis iMEMS® Accelerometer | 获取价格 |
|
| AD22293Z-RL | ADI | Precision ±1.7 g, ±5 g, ±18 g Dual-Axis iMEMS® Accelerometer | 获取价格 |
|
| AD22293ZA | ADI | Precision 1.7g, -1.7g, 5g, -5g, 18g, -18g Single-/ Dual-Axis iMEMS Accelerometer | 获取价格 |
|
| AD22300 | ADI | Single-Axis, High-g, iMEMS® Accelerometers | 获取价格 |
|
| AD22301 | ADI | Single-Axis, High-g, iMEMS ccelerometers | 获取价格 |
|
| AD22302 | ADI | Small, Low Power, Dual Axis High-g iMEMS® Accelerometer With Analog Output | 获取价格 |
|
AD22284-A-R2 相关文章
Bourns 密封通孔金属陶瓷微调电位计产品选型手册(英文版)
- 2024-09-20
- 6
Bourns 精密环境传感器产品选型手册(英文版)
- 2024-09-20
- 9
Bourns POWrTher 负温度系数(NTC)热敏电阻手册 (英文版)
- 2024-09-20
- 8
Bourns GMOV 混合过压保护组件产品选型手册(英文版)
- 2024-09-20
- 6
