MXA2500J [ETC]
Ultra Low Cost, ±1.0 g Dual Axis Accelerometer with Absolute Outputs; 超低成本， 【 1.0克双轴加速度计输出的绝对
| 型号： | MXA2500J |
| 厂家： | 
ETC |
| 描述： | Ultra Low Cost, ±1.0 g Dual Axis Accelerometer with Absolute Outputs |
| 文件： | 总8页 (文件大小：303K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Ultra Low Cost,
±1.0 g Dual Axis Accelerometer
with Absolute Outputs
MXA2500J/K
FEATURES
RoHS Compliant
Sck
(optional)
Internal
Oscillator
Temperature
Sensor
Tout
Dual axis accelerometer
Voltage
Reference
Monolithic CMOS construction
On-chip mixed mode signal processing
Resolution better than 2 mg
30Hz bandwidth
Vref
CLK
Continous
Self Test
Heater
Control
2.70V to 5.25V single supply operation
Low height surface mount package
Low Pass
Filter
X axis
Aout X
Aout Y
Factory Adjust
Offset & Gain
APPLICATIONS
Consumer Electronics
Low Pass
Filter
Y axis
•
Cell phones, PDAs, MP3 Players, Gaming
consoles
2-AXIS
SENSOR
•
•
•
•
•
•
Screen and image orientation
Tilt and motion input
Menu navigation
Auto power on/off
Active HDD protection
Pedometer
Vdd
Gnd
Vda
MXA2500J/K FUNCTIONAL BLOCK DIAGRAM
The MXA2500J/K design is based on heat convection
and requires no solid proof mass. This eliminates
stiction and particle problems, leading to significantly
lower failure rates and lower loss due to handling
during assembly.
Security
•
•
•
Tamper detection
Catastrophic event detection
Black box event recorders
The MXA2500J/K provides two absolute analog
outputs.
Office Equipment
•
•
Computer Peripherals
Mouse input
The typical noise floor is 1.0 mg/ Hz allowing signals
below 2mg to be resolved at 1Hz bandwidth. The
MXA2500J/K has an inherent low pass frequency
response with a 30Hz 3dB cutoff frequency, which
eliminates unwanted higher frequency vibrations from
obscuring the measurement. The MXA2500J/K is
available in a LCC surface mount package (5.5mm x
5.5mm x 1.40mm height, with maximum height of
1.50mm). It is operational over a 0°C to +70°C (J)
and -40°C to +85°C (K) temperature range.
GENERAL DESCRIPTION
The MXA2500J/K is an ultra low cost, dual axis
accelerometer fabricated on a standard, submicron
CMOS process. The MXA2500J/K measures
acceleration with a full-scale range of ±1.0 g and a
sensitivity of 500mV/g @3V power supply at 25°C. It
can measure both dynamic acceleration (e.g.,
vibration) and static acceleration (e.g., gravity).
Information furnished by MEMSIC is believed to be accurate and reliable.
However, no responsibility is assumed by MEMSIC 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 MEMSIC.
©MEMSIC, Inc.
800 Turnpike Street, Suite 202 , North Andover, MA 01845
Tel: 978.738.0900
www.memsic.com
Fax: 978.738.0196
MEMSIC MXA2500J/K Rev.A
Page 1 of 8
2/17/2006
MXA2500J/K SPECIFICATIONS (Measurements @ 25°C, Acceleration = 0 g unless otherwise noted; VDD,
DA = 3.0V unless otherwise specified)
V
MXA2500J
Typ
MXA2500K
Typ
Parameter
Conditions
Units
Min
Max
Min
Max
SENSOR INPUT
Measurement Range1
Nonlinearity
Each Axis
g
% of
FS
degree
s
±1.0
±1.0
Best fit straight line
1.0
2.0
1.0
2.0
Alignment Error2
±1.0
±2.0
±1.0
±2.0
Transverse Sensitivity3
%
SENSITIVITY
Each Axis
Sensitivity, Analog Outputs at
pins AOUTX and AOUTY
Change over Temperature
ZERO g BIAS LEVEL
0 g Offset
@3.0V supply
∆ from 25°C
Each Axis
450
500
550
10
450
500
550
20
mV/g
%
-0.3
1.10
0.00
1.25
±3.0
±1.5
+0.3
1.40
-0.3
1.10
0.00
1.25
±3.0
±1.5
+0.3
1.40
g
V
0 g Voltage
0 g Offset over Temperature
∆ from 25°C
∆ from 25°C, based on
500mV/g
mg/°C
mV/°C
NOISE PERFORMANCE
Noise Density, rms
mg/
Without frequency
compensation
1.0
30
1.0
30
Hz
FREQUENCY RESPONSE
3dB Bandwidth -
25
35
25
35
Hz
uncompensated
TEMPERATURE OUTPUT
Tout Voltage
Sensitivity
1.15
4.6
1.25
5.0
1.35
5.4
1.15
4.6
1.25
5.0
1.35
5.4
V
mV/°K
VOLTAGE REFERENCE
VRef
Change over Temperature
@2.7V-5.25V supply
Source
2.4
2.5
0.1
2.65
100
2.4
2.5
0.1
2.65
100
V
mV/°C
µA
Current Drive Capability
SELF TEST
Continuous Voltage at AOUTX
AOUTY under Failure
,
@3.0V Supply, output
rails to
3.0
3.0
V
supply voltage
AOUTX and AOUTY OUTPUTS
Normal Output Range
Current
@3.0V Supply
Source or sink, @ 2.7V-
5.25V supply
0.1
2.9
100
0.1
2.9
100
V
µA
Turn-On Time4
@3.0V Supply
300
4.8
300
4.8
mS
POWER SUPPLY
Operating Voltage Range
Supply Current
TEMPERATURE RANGE
Operating Range
2.7
0
5.25
+70
2.7
-40
5.25
105
V
mA
@ 3.0V
°C
NOTES
1
Guaranteed by measurement of initial offset and sensitivity.
Alignment error is specified as the angle between the true and
2
indicated axis of sensitivity.
3
Transverse sensitivity is the algebraic sum of the alignment and
the inherent sensitivity errors.
4
Output settled to within +/-17mg.
MEMSIC MXA2500J/K Rev.A
Page 2 of 8
2/17/2006
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage (VDD, VDA)
………………...-0.5 to
+7.0V
Storage Temperature …….………… -65°C to +150°C
Acceleration ……………………………………..50,000
g
*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.
Package Characteristics
Pin Description: LCC8 Package
Package
Device Weight
< 1 gram
θJA
θJC
Pin
1
2
3
4
Name
TOUT
AOUTY
Gnd
VDA
Description
LCC8
110°C/W 22°C/W
Temperature (Analog Voltage)
Y-Axis Acceleration Signal
Ground
Analog Supply Voltage
X-Axis Acceleration Signal
2.5V Reference
Ordering Guide
Model
Temperature
Range
Package Style
5
6
AOUTX
Vref
MXA2500JV
MXA2500KV
0~70°C
LCC8,
RoHS compliant
LCC8,
7
8
Sck
VDD
Connect to Ground
Digital Supply Voltage
-40~85°C
RoHS compliant
THEORY OF OPERATION
*LCC parts are shipped in tape and reel packaging.
The MEMSIC device is a complete dual-axis
acceleration measurement system fabricated on a
monolithic CMOS IC process. The device operation is
based on heat transfer by natural convection and
operates like other accelerometers having a proof
mass except it is a gas in the MEMSIC sensor.
Caution
ESD (electrostatic discharge) sensitive device.
A single heat source, centered in the silicon chip is
suspended across a cavity. Equally spaced
aluminum/poly-silicon thermopiles (groups of
thermocouples) are located equidistantly on all four
sides of the heat source (dual axis). Under zero
acceleration, a temperature gradient is symmetrical
about the heat source, so that the temperature is the
same at all four thermopiles, causing them to output
the same voltage.
8
1
2
3
7
6
5
X +g
4
Y +g
Top View
Acceleration in any direction will disturb the
temperature profile, due to free convection heat
transfer, causing it to be asymmetrical. The
temperature, and hence voltage output of the four
thermopiles will then be different. The differential
voltage at the thermopile outputs is directly
proportional to the acceleration. There are two
identical acceleration signal paths on the
Note: The MEMSIC logo’s arrow indicates the +X sensing
direction of the device. The +Y sensing direction is rotated
90° away from the +X direction.
accelerometer, one to measure acceleration in the x-
axis and one to measure acceleration in the y-axis.
MEMSIC MXA2500J/K Rev.A
Page 3 of 8
2/17/2006
TYPICAL CHARACTERISTICS, % OF UNITS (@ 25°C, VDD = 3V)
OffsetX Distribution
OffsetY Distribution
14%
14%
12%
12%
10%
8%
6%
4%
2%
0%
10%
8%
6%
4%
2%
0%
1.126 1.159 1.192 1.225 1.258 1.291 1.324 1.357 1.390
1.126 1.159 1.192 1.225 1.258 1.291 1.324 1.357 1.390
SenX Distribution
SenY Distribution
60%
50%
40%
30%
20%
10%
0%
60%
50%
40%
30%
20%
10%
0%
465
474
484
493
502
512
521
531
540
465
474
484
493
502
512
521
531
540
MEMSIC MXA2500J/K Rev.A
Page 4 of 8
2/17/2006
OVER TEMPERATURE CHARACTERISTICS
Normalized OffsetY vs. Temp
Normalized OffsetX vs. Temp
1.20
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
T(C)
T(C)
0
10
20
30
40
50
60
70
0
10
20
30
40
50
60
70
Normalized SenX vs. Temp
Normalized SenY vs. Temp
1.06
1.04
1.02
1.00
0.98
0.96
0.94
1.06
1.04
1.02
1.00
0.98
0.96
0.94
T(C)
T(C)
0
10
20
30
40
50
60
70
0
10
20
30
40
50
60
70
MEMSIC MXA2500J/K Rev.A
Page 5 of 8
2/17/2006
X
PIN DESCRIPTIONS
+900
VDD – This is the supply input for the digital circuits and
the sensor heater in the accelerometer. The DC voltage
should be between 2.70 and 5.25 volts.
gravity
00
VDA – This is the power supply input for the analog
amplifiers in the accelerometer. The DC voltage should
be between 2.70 and 5.25 volts
Y
Top View
Accelerometer Position Relative to Gravity
Gnd – This is the ground pin for the accelerometer.
X-Axis
Change
Y-Axis
Change
AOUTX – This pin is the output of the x-axis
acceleration sensor. The user should ensure the load
impedance is sufficiently high as to not source/sink
>100µA.
X-Axis
Orientation
To Earth’s
Surface
X
per deg.
of tilt
(mg)
0.15
Y
per deg.
of tilt
(mg)
17.45
17.37
17.16
16.35
15.04
12.23
8.59
Output
(g)
Output
(g)
AOUTY – This pin is the output of the y-axis acceleration
sensor. The user should ensure the load impedance
is sufficiently high as to not source/sink >100µA.
(deg.)
90
85
80
70
60
45
30
20
10
5
1.000
0.996
0.985
0.940
0.866
0.707
0.500
0.342
0.174
0.087
0.000
0.000
0.087
0.174
0.342
0.500
0.707
0.866
0.940
0.985
0.996
1.000
1.37
2.88
5.86
8.59
TOUT – This pin is the buffered output of the
temperature sensor. The analog voltage at TOUT is an
indication of the die temperature. This voltage is
useful as a differential measurement of temperature
from ambient and not as an absolute measurement of
temperature.
12.23
15.04
16.35
17.16
17.37
17.45
5.86
2.88
1.37
0.15
0
Sck – This pin should be grounded.
Changes in Tilt for X- and Y-Axes
Vref – A reference voltage is available from this pin. It is
set at 2.50V typical and has 100µA of drive capability.
Minimum Resolution: The accelerometer resolution is
limited by noise. The output noise will vary with the
measurement bandwidth. With the reduction of the
bandwidth, by applying an external low pass filter, the
output noise drops. Reduction of bandwidth will improve
the signal to noise ratio and the resolution. The output
noise scales directly with the square root of the
measurement bandwidth. The maximum amplitude of
the noise, its peak- to- peak value, approximately
defines the worst-case resolution of the measurement.
The peak-to-peak noise is approximately equal to 6.6
times the rms value (with an average uncertainty
of .1%).
DISCUSSION OF TILT APPLICATIONS AND
MINIMUM RESOLUTION
Tilt Applications: One of the most popular applications
of the MEMSIC accelerometer product line is in
tilt/inclination measurement. An accelerometer uses the
force of gravity as an input to determine the inclination
angle of an object.
A MEMSIC accelerometer is most sensitive to changes
in position, or tilt, when the accelerometer’s sensitive
axis is perpendicular to the force of gravity, or parallel to
the Earth’s surface. Similarly, when the accelerometer’s
axis is parallel to the force of gravity (perpendicular to
the Earth’s surface), it is least sensitive to changes in
tilt.
EXTERNAL FILTERS
AC Coupling: For applications where only dynamic
accelerations (vibration) are to be measured, it is
recommended to ac couple the accelerometer output as
shown in following figure. The advantage of ac coupling
is that variations from part to part of zero g offset and
zero g offset versus temperature can be eliminated.
Following figure is a HPF (high pass filter) with a –3dB
1
Following table and figure help illustrate the output
changes in the X- and Y-axes as the unit is tilted from
+90° to 0°. Notice that when one axis has a small
change in output per degree of tilt (in mg), the second
axis has a large change in output per degree of tilt. The
complementary nature of these two signals permits low
cost accurate tilt sensing to be achieved with the
MEMSIC device (reference application note AN-00MX-
007).
breakpoint given by the equation: f =
. In many
2πRC
applications it may be desirable to have the HPF –3dB
point at a very low frequency in order to detect very low
frequency accelerations. Sometimes the
MEMSIC MXA2500J/K Rev.A
Page 6 of 8
2/17/2006
implementation of this HPF may result in unreasonably
large capacitors, and the designer must turn to digital
implementations of HPFs where very low frequency –
3dB breakpoints can be achieved.
Power supply
VDA
VDD
C1
C
AOUTX
Filtered
Output
R
AOUTX
0.1uF
MEMSIC
Accelerometer
C
AOUTY
AOUTY
Filtered
Output
Power Supply Noise Rejection
PCB LAYOUT AND FABRICATION SUGGESTIONS
1. The Sck pin should be grounded to minimize noise.
2. Liberal use of ceramic bypass capacitors is
recommended.
R
High Pass Filter
3. Robust low inductance ground wiring should be
used.
Low Pass Filter: An external low pass filter is useful in
low frequency applications such as tilt or inclination.
The low pass filter limits the noise floor and improves
the resolution of the accelerometer. When designing
with MEMSIC ratiometric output accelerometers
(MXR2xxx series), it is highly recommended that an
external, 200 Hz low pass filter be used to eliminate
internally generated periodic noise that is coupled to the
output of the accelerometer.
4. Care should be taken to ensure there is “thermal
symmetry” on the PCB immediately surrounding the
MEMSIC device and that there is no significant heat
source nearby.
5. A metal ground plane should be added directly
beneath the MEMSIC device. The size of the
ground plane should be similar to the MEMSIC
device’s footprint and as thick as possible.
6. Vias can be added symmetrically around the ground
plane. Vias increase thermal isolation of the device
from the rest of the PCB.
The low pass filter shown in following figure has a –3dB
1
breakpoint given by the equation: f =
. For the
2πRC
200 Hz ratiometric output device filter, C=0.1µF and
R=8kΩ, ±5%, 1/8W.
R
AOUTX
Filtered
Output
AOUTX
C
C
R
AOUTY
Filtered
Output
AOUTY
Low Pass Filter
POWER SUPPLY NOISE REJECTION
A capacitor is recommended for best rejection of power
supply noise (reference following figure). The capacitor
should be located as close as possible to the device
supply pins VDA. The capacitor lead length should be as
short as possible, and surface mount capacitors are
preferred. For typical applications, capacitors C1 can be
ceramic 0.1 µF.
MEMSIC MXA2500J/K Rev.A
Page 7 of 8
2/17/2006
Package Drawing
CERAMIC
(BLACK)
Package Outline
MEMSIC MXA2500J/K Rev.A
Page 8 of 8
2/17/2006
相关型号：
MXA6500EP
Low Profile, Low Consumption 0.5 g Dual Axis Accelerometer with Absolute Analog Outputs
ETC
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