Low Power, Low Profile
±
1.5
g
Dual Axis Accelerometer with
2
I C Interface
MXC6232xE/F
FEATURES
RoHS compliant
I
2
C Slave, FAST (≤400 KHz.) mode interface
1.8V compatible I/O
Embedded Power up/down and self-test function
On-chip temperature sensor
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, Mouse, Smart Pens
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 MXC6232xE/F 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
MXC6232xE/F measures acceleration with a full-scale
range of
±1.5
g
and a sensitivity of 512counts/g (E) or
128counts/g (F) @3.0 V at 25
°C
. It can measure both
dynamic acceleration (e.g. vibration) and static
acceleration (e.g. gravity). The MXC6232xE/F design is
based on heat convection and requires no solid proof mass.
MXC6232xE/F FUNCTIONAL BLOCK DIAGRAM
The MXC6232xE/F 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 -40°C to +105°C.
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 MXC6232xE/F provides I
2
C digital output with 400
KHz, fast mode operation.
The maximum noise floor is 1mg/
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: +1 978 738 0900
Fax: +1 978 738 0196
www.memsic.com
MEMSIC MXC6232xE/F Rev.A
Page 1 of 9
4/11/2010
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
Conditions
Each Axis
Best fit straight line
Min
±1.5
Typ
0.5
±1.0
±2.0
512
128
Max
1.0
Units
g
% of FS
degrees
%
counts/g
counts/g
%
MXC6232xE
MXC6232xF
Sensitivity Change Over Temperature
∆
from 25°C at -40°C
∆
from 25°C at +105°C
Zero
g
Offset Bias Level
MXC6232xE
MXC6232xF
Zero
g
Offset TC
∆
from 25°C
Tout
MXC6232xE
MXC6232xF
Tout Sensitivity
MXC6232xE
MXC6232xF
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
486
118
-60
1996
492
3195
0.196
0.753
538
138
155
2048
512
0.4
3375
840
0.217
0.833
0.5
0.5
17
1.0
75
3.0
1.8
2100
532
3555
0.244
0.936
1.0
19
100
100
3.6
2.5
1.0
+105
counts
counts
mg/°C
counts
counts
°C/count
°C/count
mg/
Hz
mg
Hz
G
µA
mS
V
mA
µA
°C
@ 1Hz. BW
@ -3dB
@ 2.7 V – 3.6 V
15
2.7
-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 MXC6232xE/F
Rev.A
Page 2 of 9
4/11/2010
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 MXC6232xE/F
Rev.A
Page 3 of 9
4/11/2010
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
Ordering Guide
MXC6232xEP
Package type:
Code
P
B
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).
Type
LCC8
RoHS compliant
LCC8, Pb-free
RoHS compliant
Resolution
12bits
10bits
Performance Grade:
Code
Temp
E
-40~105°C
F
-40~105°C
Address code: 0~7
Number Address
0
20H
1
22H
2
24H
3
26H
4
28H
5
2AH
6
2CH
7
2EH
All parts are shipped in tape and reel packaging.
Caution:
ESD (electrostatic discharge) sensitive device.
MEMSIC MXC6232xE/F
Rev.A
Page 4 of 9
4/11/2010
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 that the proof mass in the MEMSIC sensor is a gas.
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.
COMPENSATION FOR THE CHANGE IN
SENSITIVITY OVER TEMPERATURE
All thermal accelerometers display the same sensitivity
change with temperature. The sensitivity change depends
on variations in heat transfer that are governed by the laws
of physics. The sensitivity change is governed by the
following equation (and shown in following figure in
°C):
S
i
x T
i3.50
= S
f
x T
f3.50
where S
i
is the sensitivity at any initial temperature T
i
, and
S
f
is the sensitivity at any other final temperature T
f
with
the temperature values in
°K.
2.5
Sensitivity (normalized)
2.0
1.5
1.0
0.5
0.0
-40
-20
0
20
40
60
80
100
Temperature (C)
Thermal Accelerometer Sensitivity
MXC6232xE/F PIN DESCRIPTIONS
VDD
– 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.
In gaming applications where the game or controller is
typically used in a constant temperature environment,
sensitivity might not need to be compensated in hardware
or software. Any compensation for this effect could be
done instinctively by the game player.
For applications where sensitivity changes of a few percent
are acceptable, the above equation can be approximated
with a linear function. Using a linear approximation, an
external circuit that provides a gain adjustment of –
1.1%/°C would keep the sensitivity within 10% of its room
temperature value over a 0°C to +50°C range.
For applications that demand high performance, a low cost
micro-controller can be used to implement the above
equation. A reference design using a Microchip MCU (p/n
16F873/04-SO) and MEMSIC developed firmware is
available by contacting the factory. With this reference
design, the sensitivity variation over the full temperature
range (-40°C to +105°C) can be kept below 3%. Please
visit the MEMSIC web site at
www.memsic.com
for
reference design information on circuits and programs
including look up tables for easily incorporating sensitivity
compensation.
MEMSIC MXC6232xE/F
Rev.A
Page 5 of 9
4/11/2010
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