Ultra Low Cost,
±1.0
g
Dual Axis Accelerometer
with Absolute Outputs
MXA2500J/K
FEATURES
RoHS Compliant
Dual axis accelerometer
Monolithic CMOS construction
On-chip mixed mode signal processing
Resolution better than 2 mg
30Hz bandwidth
2.70V to 5.25V single supply operation
Low height surface mount package
Sck
(optional)
Internal
Oscillator
Temperature
Sensor
Voltage
Reference
Continous
Self Test
Tout
CLK
Vref
Heater
Control
X axis
Low Pass
Filter
Aout X
APPLICATIONS
Consumer Electronics
•
Cell phones, PDAs, MP3 Players, Gaming
consoles
•
Screen and image orientation
•
Tilt and motion input
•
Menu navigation
•
Auto power on/off
•
Active HDD protection
•
Pedometer
Security
•
Tamper detection
•
Catastrophic event detection
•
Black box event recorders
Office Equipment
•
Computer Peripherals
•
Mouse input
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).
2-AXIS
SENSOR
Factory Adjust
Offset & Gain
Low Pass
Filter
Y axis
Aout Y
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.
The MXA2500J/K provides two absolute analog
outputs.
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.
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
Fax: 978.738.0196
www.memsic.com
MEMSIC MXA2500J/K Rev.A
Page 1 of 8
2/17/2006
MXA2500J/K SPECIFICATIONS
(Measurements @ 25°C, Acceleration = 0
g
unless otherwise noted; V
DD
,
V
DA
= 3.0V unless otherwise specified)
MXA2500J
Parameter
SENSOR INPUT
Measurement Range
1
Nonlinearity
Alignment Error
2
Transverse Sensitivity
3
SENSITIVITY
Sensitivity, Analog Outputs at
pins A
OUTX
and A
OUTY
Change over Temperature
ZERO
g
BIAS LEVEL
0
g
Offset
0
g
Voltage
0
g
Offset over Temperature
Each Axis
@3.0V supply
∆
from 25°C
Each Axis
∆
from 25°C
∆
from 25°C, based on
500mV/g
Without frequency
compensation
25
450
500
550
10
+0.3
1.40
450
500
550
20
+0.3
1.40
mV/g
%
g
V
mg/°C
mV/°C
mg/
Conditions
Each Axis
±1.0
Best fit straight line
1.0
±1.0
±2.0
2.0
±1.0
1.0
±1.0
±2.0
2.0
g
% of
FS
degree
s
%
Min
Typ
Max
Min
MXA2500K
Typ
Max
Units
-0.3
1.10
0.00
1.25
±3.0
±1.5
-0.3
1.10
0.00
1.25
±3.0
±1.5
NOISE PERFORMANCE
Noise Density, rms
FREQUENCY RESPONSE
3dB Bandwidth -
uncompensated
TEMPERATURE OUTPUT
T
out
Voltage
Sensitivity
VOLTAGE REFERENCE
V
Ref
Change over Temperature
Current Drive Capability
SELF TEST
Continuous Voltage at A
OUTX
,
A
OUTY
under Failure
A
OUTX
and A
OUTY
OUTPUTS
Normal Output Range
Current
Turn-On Time
4
POWER SUPPLY
Operating Voltage Range
Supply Current
TEMPERATURE RANGE
Operating Range
NOTES
1.0
1.0
Hz
30
35
25
30
35
Hz
1.15
4.6
@2.7V-5.25V supply
Source
@3.0V Supply, output
rails to
supply voltage
@3.0V Supply
Source or sink, @ 2.7V-
5.25V supply
@3.0V Supply
2.7
@ 3.0V
0
0.1
2.4
1.25
5.0
2.5
0.1
1.35
5.4
2.65
100
1.15
4.6
2.4
1.25
5.0
2.5
0.1
1.35
5.4
2.65
100
V
mV/°K
V
mV/°C
µA
V
3.0
3.0
2.9
100
300
5.25
4.8
+70
0.1
2.9
100
300
V
µA
mS
2.7
4.8
-40
5.25
V
mA
°C
105
Guaranteed by measurement of initial offset and sensitivity.
Alignment error is specified as the angle between the true and
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.
2
1
MEMSIC MXA2500J/K Rev.A
Page 2 of 8
2/17/2006
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage (V
DD
, V
DA
)
………………...-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
Package
θ
JA
θ
JC
LCC8
110°C/W 22°C/W
Device Weight
< 1 gram
Ordering Guide
Model
MXA2500JV
MXA2500KV
Temperature
Range
0~70
°C
-40~85
°C
Package Style
LCC8,
RoHS compliant
LCC8,
RoHS compliant
Pin Description:
Pin
Name
1
T
OUT
2
A
OUTY
3
Gnd
4
V
DA
5
A
OUTX
6
V
ref
7
Sck
8
V
DD
LCC8 Package
Description
Temperature (Analog Voltage)
Y-Axis Acceleration Signal
Ground
Analog Supply Voltage
X-Axis Acceleration Signal
2.5V Reference
Connect to Ground
Digital Supply Voltage
*LCC parts are shipped in tape and reel packaging.
Caution
ESD (electrostatic discharge) sensitive device.
THEORY OF OPERATION
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.
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.
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
accelerometer, one to measure acceleration in the x-
axis and one to measure acceleration in the y-axis.
8
1
2
3
M E M S IC
7
X +g
6
5
4
Y +g
Top View
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.
MEMSIC MXA2500J/K Rev.A
Page 3 of 8
2/17/2006
TYPICAL CHARACTERISTICS, % OF UNITS (@ 25°C, V
DD
= 3V)
OffsetX Distribution
14%
12%
10%
8%
6%
4%
2%
0%
1.126 1.159 1.192 1.225 1.258 1.291 1.324 1.357 1.390
14%
12%
10%
8%
6%
4%
2%
0%
OffsetY Distribution
1.126 1.159 1.192 1.225 1.258 1.291 1.324 1.357 1.390
SenX Distribution
60%
60%
SenY Distribution
50%
50%
40%
40%
30%
30%
20%
20%
10%
10%
0%
465
474
484
493
502
512
521
531
540
0%
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 OffsetX vs. Temp
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
0
10
20
30
40
50
60
T(C)
70
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
0
10
Normalized OffsetY vs. Temp
T(C)
20
30
40
50
60
70
Normalized SenX vs. Temp
1.06
1.06
Normalized SenY vs. Temp
1.04
1.04
1.02
1.02
1.00
1.00
0.98
0.98
0.96
T(C)
0
10
20
30
40
50
60
70
0.96
T(C)
0.94
0
10
20
30
40
50
60
70
0.94
MEMSIC MXA2500J/K Rev.A
Page 5 of 8
2/17/2006
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