Low Power, Low Profile
±
2
g
Dual Axis Accelerometer with
2
I C Interface
MXC6232xM
FEATURES
RoHS compliant
I
2
C Slave, FAST (≤400 KHz.) mode interface
1.8V compatible IO
Embedded Power up/down and self-test function
On-chip temperature sensor available
Eight customer defined 7-bit addresses
2.7 V to 3.6 V single supply continuous operation
Monolithic CMOS IC
Low power consumption: typically <2 mA @ 3.0 V
Resolution better than 1 mg
On chip mixed signal processing
>50,000
g
shock survival rating
Low profile LCC package: 5mm
X
5mm
X
1.55mm
TEMP
TP
Internal
Oscillator
VREF
Temperature
Sensor
TEMP
Coarse
Gain Adj.
Fine Gain
Adj.
No
Connection
A/D
No
Connection
VDD
CLK
PD
CLK
Heater
Control
X aixs
CLK
Coarse
Gain Adj.
Temp
Comp.
CLK TEMP CLK
Fine Gain
Adj.
Temp
Comp.
IIC Convertor
SCL
SDA
A/D
CLK
CLK
Y aixs
Acceleration
Sensor
CLK
CLKTEMP
GND
APPLICATIONS
Information Appliances –
Cell Phones, PDA’s, Computer
Peripherals
Consumer –
LCD Projectors, Pedometers, Blood Pressure
Monitor, Digital Cameras
Gaming
– Joystick/RF Interface/Menu Selection/Tilt
Sensing
GPS
–
Electronic Compass Tilt Correction, Dead
Reckoning Assist
GENERAL DESCRIPTION
The MXC6232xM is low cost, dual axis accelerometers
fabricated on a standard, submicron CMOS process. It is a
complete sensing system with on-chip mixed signal
processing and integrated I
2
C bus, allowing the device to
be connected directly to a microprocessor eliminating the
need for A/D converters or timing resources. The
MXC6232xM measures acceleration with a full-scale
range of
±2
g
and a sensitivity of 512counts/g @3.0 V at
25
°C
. It can measure both dynamic acceleration (e.g.
vibration) and static acceleration (e.g. gravity). The
MXC6232xM design is based on heat convection and
requires no solid proof mass.
MXC6232xM FUNCTIONAL BLOCK DIAGRAM
This design eliminates the stiction problems associated
with legacy technologies and provides shock survival
greater than 50,000g’s. Memsic’s solid state design leads
to significantly lower failure rates in customer applications
and lower loss due to handling during manufacturing and
assembly processes
The MXC6232xM is packaged in a hermetically sealed,
low profile LCC surface mount package (5 mm x 5 mm x
1.55 mm) and is available in operating temperature ranges
of and-40°C to +85°C.
The MXC6232xM provides I
2
C digital output with 400
KHz, fast mode operation.
The maximum noise floor is 1 mg/
Hz
allowing signals
below 1mg to be resolved at 1 Hz bandwidth
Information furnished by MEMSIC is believed to be accurate and reliable. However, no
responsibility is assumed by MEMSIC for its use, or 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.
One Technology Drive Suite 325,Andover MA01810,USA
Tel: 978.738.0900
Fax: 978.738.0196
www.memsic.com
MEMSIC MXC6232xM Rev.B
Page 1 of 9
2/6/2013
ELECTRICAL CHARACTERISTICS
(Measurements @ 25°C, Acceleration = 0
g
unless otherwise noted; V
DD
= 3.0V unless
otherwise specified)
Parameter
Measurement Range
1
Nonlinearity
Alignment Error
2
Transverse Sensitivity
3
Sensitivity
Sensitivity Change Over Temperature
Zero
g
Offset Bias Level
Zero
g
Offset TC
Tout
Tout Sensitivity
Noise Density, RMS
Resolution
Frequency Response
Self-test
Output Drive Capability
Turn-On Time
4
Operating Voltage Range
Supply Current
Power Down Current
Operating Temperature Range
NOTES:
1
2
Conditions
Each Axis
Best fit straight line
Min
±2.0
Typ
0.5
±1.0
±2.0
512
Max
1.0
Units
G
% of FS
degrees
%
counts/g
%
counts
mg/°C
counts
counts/°C
mg/
Hz
mg
Hz
G
µA
mS
V
mA
µA
°C
486
∆
from 25°C
-15
1996
∆
from 25°C
2550
2.00
within 20Hz
@ 1Hz. BW
@ -3dB
@ 2.7 V – 3.6 V
2.7
15
1.7
538
+10
2100
2870
2.60
1.0
1.0
19
2.7
100
100
3.6
2.5
1.0
+85
2048
0.8
2710
2.33
0.7
0.5
17
2.2
75
3.0
1.8
-40
Guaranteed by measurement of initial offset and sensitivity
Alignment error is specified as the angle between the true and indicated axis
of sensitivity
Cross axis sensitivity is the algebraic sum of the alignment and the inherent
sensitivity errors
4
3
Output settled to within
±
17mg
MEMSIC MXC6232xM
Rev.B
Page 2 of 9
2
/6/2013
I
2
C INTERFACE I/O CHARACTERISTICS
Parameter
Logic Input Low Level
Logic Input High Level
Hysteresis of Schmitt input
Logic Output Low Level
Input Leakage Current
SCL Clock Frequency
START Hold Time
START Setup Time
LOW period of SCL
HIGH period of SCL
Data Hold Time
Data Setup Time
Rise Time
Fall Time
Bus Free Time Between STOP and
START
STOP Setup Time
Symbol
V
IL
V
IH
V
hys
V
OL
I
i
f
SCL
t
HD;STA
t
SU;STA
t
LOW
t
HIGH
t
HD;DAT
t
SU;DAT
t
r
t
f
t
BUF
t
SU;STO
Test Condition
Min.
-0.5
1.4
0.2
Typ.
Max.
0.6
Unit
V
V
V
0.4
0.1Vdd<V
in
<0.9Vdd
-10
0
0.6
0.6
1.3
0.6
0
0.1
From V
IL
to V
IH
From V
IH
to V
IL
1.3
0.6
0.3
0.3
0.9
10
400
µA
kHz
µS
µS
µS
µS
µS
µS
µS
µS
µS
µS
SDA
t
f
t
LOW
t
r
t
SU;DAT
t
f
t
HD;STA
t
SP
t
r
t
BUF
SCL
t
HD;STA
S
t
HIGH
t
SU;STA
t
SU;STO
t
HD;DAT
Sr
P
S
Timing Definition
MEMSIC MXC6232xM
Rev.B
Page 3 of 9
2
/6/2013
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage (V
DD
) ………………...-0.5 V 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.
Pin Description: LCC-8 Package
Pin
Name
Description
1
NC
Do Not Connect
2
COM
Connected to Ground
3
GND
Connected to Ground
4
TEST
Do Not Connect
5
VDD2 Power Supply for I
2
C bus
6
SCL
Serial Clock Line for I
2
C bus
7
SDA
Serial Data Line for I
2
C bus
8
V
DD
2.7 V to 3.6 V
All parts are shipped in tape and reel packaging.
Caution:
ESD (electrostatic discharge) sensitive device.
I/O
NC
I
I
NC
I
I
I/O
I
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 following the right-hand rule. Small
circle indicates pin one (1).
Ordering Guide
MXC6232xMP
Package type:
Code
P
Type
LCC8
RoHS compliant
Performance Grade:
Code
Temp
M
-40~85°C
Resolution
4096counts
Address code: 0~7
Number Address
0
20H
1
22H
2
24H
3
26H
4
28H
5
2AH
6
2CH
7
2EH
Factory default address is 0 or 5,
others are available with a
minimum order quantity (MOQ) of
MEMSIC MXC6232xM
Rev.B
Page 4 of 9
2
/6/2013
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
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/polysilicon 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. Please visit the MEMSIC
website at www.memsic.com for a picture/graphic
description of the free convection heat transfer principle.
DISCUSSION OF TILT APPLICATIONS AND
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.
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).
MXC6232xM PIN DESCRIPTIONS
V
DD
– This is the supply input for the circuits and the
sensor heater in the
accelerometer
. The DC voltage should
be between 2.7 and 3.6 volts. Refer to the section on PCB
layout and fabrication suggestions for guidance on external
parts and connections recommended.
GND–
This is the ground pin for the
accelerometer
.
COM–
This pin should be connected to ground.
TEST–
Do Not Connect, factory use only.
VDD2–
This pin is the I
2
C input digital power supply, the
voltage on this pin determines the I
2
C bus logic voltage,
and is 1.8V compatible. Note: The voltage on this pin
should never go higher than the voltage on V
DD
, if VDD2
has a lower power supply voltage than V
DD
, power should
be applied to V
DD
first.
SDA–
This pin is the I
2
C serial data line, and operates in
FAST (400 KHz.) mode.
SCL–
This pin is the I
2
C serial clock line, and operates in
FAST (400 KHz.) mode.
MEMSIC MXC6232xM
Rev.B
Page 5 of 9
Accelerometer Position Relative to Gravity
MEMSIC
X-Axis
X-Axis
Orientatio
n
To Earth’s
Surface
(deg.)
90
85
80
70
60
45
30
20
10
5
0
Y-Axis
Change
per deg.
of tilt
(mg)
17.45
17.37
17.16
16.35
15.04
12.23
8.59
5.86
2.88
1.37
0.15
X
Output
(g)
Change
per deg.
of tilt
(mg)
Y
Output
(g)
1.000
0.15
0.000
0.996
1.37
0.087
0.985
2.88
0.174
0.940
5.86
0.342
0.866
8.59
0.500
0.707
12.23
0.707
0.500
15.04
0.866
0.342
16.35
0.940
0.174
17.16
0.985
0.087
17.37
0.996
0.000
17.45
1.000
Changes in Tilt for X- and Y-Axes
2
/6/2013
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