MMA2301D [MOTOROLA]
Surface Mount Micromachined Accelerometer; 表面贴装微机械加速度计
| 型号： | MMA2301D |
| 厂家： | 
MOTOROLA |
| 描述： | Surface Mount Micromachined Accelerometer |
| 文件： | 总7页 (文件大小：146K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Freescale Semiconductor, Inc.
MOTOROLA
Order Number: MMA2301D
Rev. 2, 06/2004
SEMICONDUCTOR TECHNICAL DATA
Surface Mount Micromachined
Accelerometer
MMA2301D
The MMA series of silicon capacitive, micromachined accelerometers features
signal conditioning, a four-pole low pass filter and temperature compensation.
Zero-g offset full scale span and filter cut-off are factory set and require no external
devices. A full system self-test capability verifies system functionality.
MMA2301D: X-AXIS SENSITIVITY
MICROMACHINED
ACCELEROMETER
±200g
Features
•
•
•
•
•
•
•
•
Integral Signal Conditioning
Linear Output
Ratiometric Performance
Fourth Order Bessel Filter Preserves Pulse Shape Integrity
Calibrated Self-test
Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status
Transducer Hermetically Sealed at Wafer Level for Superior Reliability
Robust Design, High Shocks Survivability
Typical Applications
•
•
Vibration Monitoring and Recording
Impact Monitoring
16 LEAD SOIC
CASE 475-01
ORDERING INFORMATION
Device
Temperature
Range
Package
PIN ASSIGNMENT
MMA2301D
– 40 to +125°C SOIC-16
MMA2301DR2
– 40 to +125°C SOIC-16, Tape & Reel
16
15
14
13
12
11
10
9
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
ST
1
2
3
4
5
6
7
8
V
OUT
STATUS
V
SS
DD
V
V
V
DD
G-Cell
Sensor
Temp
Integrator
Gain
Filter
OUT
ST
Control Logic &
EPROM
Trim Circuits
Clock
Gen.
Oscillator
Self-Test
V
SS
Status
Figure 1. Simplified Accelerometer Functional Block Diagram
REV 2
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© Motorola, Inc. 2004
Freescale Semiconductor, Inc.
Maximum Ratings
(Maximum ratings are the limits to which the device can be exposed without causing permanent damage.)
Rating
Symbol
Value
1500
Unit
g
Powered Acceleration (all axes)
Unpowered Acceleration (all axes)
Supply Voltage
G
pd
G
V
2000
g
upd
DD
–0.3 to +7.0
1.2
V
(1)
Drop Test
D
m
drop
Storage Temperature Range
T
–40 to +125
°C
stg
NOTES:
1. Dropped onto concrete surface from any axis.
ELECTRO STATIC DISCHARGE (ESD)
WARNING: This device is sensitive to electrostatic
discharge.
Although the Motorola accelerometers contain internal 2kV
ESD protection circuitry, extra precaution must be taken by the
user to protect the chip from ESD. A charge of over 2000 volts
can accumulate on the human body or associated test
equipment. A charge of this magnitude can alter the
performance or cause failure of the chip. When handling the
accelerometer, proper ESD precautions should be followed to
avoid exposing the device to discharges which may be
detrimental to its performance.
MMA2301D
2
Motorola Sensor Device Data
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Freescale Semiconductor, Inc.
OPERATING CHARACTERISTICS
(Unless otherwise noted: -40°C ≤ TA ≤ +105°C, 4.75 ≤ VDD ≤ 5.25, Acceleration = 0g, Loaded output(1)
)
Characteristic
Symbol
Min
Typ
Max
Unit
(2)
(3)
Operating Range
Supply Voltage
Supply Current
V
4.75
3.0
-40
—
5.0
—
—
5.25
6.0
+125
—
V
mA
°C
g
DD
I
DD
Operating Temperature Range
Acceleration Range
T
g
A
225
FS
Output Signal
(4)
Zero g (T = 25°C, V = 5.0 V)
V
OFF
2.4
0.46 V
9.5
1.86
360
-1.0
2.5
0.50 V
10.0
2.0
400
—
2.6
0.54 V
10.5
2.14
440
1.0
V
V
A
DD
Zero g
V
OFF,V
DD
DD
DD
(5)
Sensitivity (T = 25°C, V = 5.0 V)
S
mV/g
mV/g/V
Hz
A
DD
Sensitivity
Bandwidth Response
Nonlinearity
S
V
f
-3dB
NL
% FSO
OUT
Noise
RMS (.01-1 kHz)
Power Spectral Density
Clock Noise (without RC load on output)
n
n
n
—
—
—
—
110
2.0
2.8
—
—
mVrms
µV/(Hz
mVpk
RMS
1/2
)
PSD
(6)
CLK
Self-Test
Output Response
Input Low
g
24
30
—
—
-100
2.0
36
0.3 x V
g
V
V
µA
ms
ST
V
V
IL
IH
IN
SS
DD
Input High
Input Loading
V
I
0.7 x V
-30
V
DD
DD
(7)
-260
10
(8)
Response Time
t
—
ST
(12)(13)
Status
Output Low (I
Output High (I
= 100 µA)
= 100 µA)
V
V
—
—
—
0.4
—
V
V
load
OL
V
-0.8
load
OH
LVD
min
DD
Minimum Supply Voltage (LVD Trip)
Clock Monitor Fail Detection Frequency
Output Stage Performance
Electrical Saturation Recovery Time
Full Scale Output Range (I
V
2.7
3.25
—
4.0
V
f
50
260
kHz
(9)
t
—
0.25
—
0.2
—
—
—
ms
V
pF
Ω
DELAY
= 200 µA)
V
V
-0.25
OUT
FSO
DD
(10)
Capacitive Load Drive
Output Impedance
C
Z
100
—
L
—
300
O
Mechanical Characteristics
(11)
Transverse Sensitivity
Package Resonance
V
f
—
—
—
10
5.0
—
% FSO
kHz
XZ,YZ
PKG
NOTES:
1. For a loaded output the measurements are observed after an RC filter consisting of a 1 kΩ resistor and a 0.01 µF capacitor to ground.
2. These limits define the range of operation for which the part will meet specification.
3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the
device may operate as a linear device but is not guaranteed to be in calibration.
4. The device can measure both + and - acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will
increase above V /2 and for negative acceleration the output will decrease below V /2.
DD
DD
5. The device is calibrated at 35g.
6. At clock frequency ≅ 70 kHz.
7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages.
8. Time for the output to reach 90% of its final value after a self-test is initiated.
9. Time for amplifiers to recover after an acceleration signal causing them to saturate.
10. Preserves phase margin (60°) to guarantee output amplifier stability.
11. A measure of the device's ability to reject an acceleration applied 90° from the true axis of sensitivity.
12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high
whenever the self-test input is high, as a means to check the connectivity of the self-test and Status pins in the application.
13. The Status pin output latches high if a Low Voltage Detection or Clock Frequency failure occurs, or the EPROM parity changes to odd. The
Status pin can be reset low if the self-test pin is pulsed with a high input for at least 100 us, unless a fault condition continues to exist.
Motorola Sensor Device Data
MMA2301D
3
For More Information On This Product,
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Freescale Semiconductor, Inc.
PRINCIPLE OF OPERATION
The Motorola accelerometer is a surface-micromachined
integrated-circuit accelerometer.
Self-Test
The sensor provides a self-test feature that allows the
The device consists of a surface micromachined capacitive
sensing cell (g-cell) and a CMOS signal conditioning ASIC
contained in a single integrated circuit package. The sensing
element is sealed hermetically at the wafer level using a bulk
micromachined cap wafer.
verification of the mechanical and electrical integrity of the
accelerometer at any time before or after installation. This
feature is critical in applications such as automotive airbag
systems where system integrity must be ensured over the life of
the vehicle. A fourth plate is used in the g-cell as a self-test
plate. When the user applies a logic high input to the self-test
pin, a calibrated potential is applied across the self-test plate
and the moveable plate. The resulting electrostatic force
(Fe = 1/2 AV2/d2) causes the center plate to deflect. The
resultant deflection is measured by the accelerometer's control
ASIC and a proportional output voltage results. This procedure
assures that both the mechanical (g-cell) and electronic
sections of the accelerometer are functioning.
The g-cell is a mechanical structure formed from
semiconductor materials (polysilicon) using semiconductor
processes (masking and etching). It can be modeled as a set of
beams attached to a movable central mass that move between
fixed beams. The movable beams can be deflected from their
rest position by subjecting the system to an acceleration
(Figure 2).
As the beams attached to the central mass move, the
distance from them to the fixed beams on one side will increase
by the same amount that the distance to the fixed beams on the
other side decreases. The change in distance is a measure of
acceleration.
Ratiometricity
Ratiometricity simply means that the output offset voltage
and sensitivity will scale linearly with applied supply voltage.
That is, as you increase supply voltage the sensitivity and offset
increase linearly; as supply voltage decreases, offset and
sensitivity decrease linearly. This is a key feature when
interfacing to a microcontroller or an A/D converter because it
provides system level cancellation of supply induced errors in
the analog to digital conversion process.
The g-cell plates form two back-to-back capacitors
(Figure 2). As the central mass moves with acceleration, the
distance between the beams change and each capacitor's
value will change, (C = NAε/D). Where A is the area of the
facing side of the beam, ε is the dielectric constant, D is the
distance between the beams, and N is the number of beams.
Status
The CMOS ASIC uses switched capacitor techniques to
measure the g-cell capacitors and extract the acceleration data
from the difference between the two capacitors. The ASIC also
signal conditions and filters (switched capacitor) the signal,
providing a high level output voltage that is ratiometric and
proportional to acceleration.
Motorola accelerometers include fault detection circuitry and
a fault latch. The Status pin is an output from the fault latch,
OR'd with self-test, and is set high whenever one (or more) of
the following events occur:
•
•
•
Supply voltage falls below the Low Voltage Detect (LVD)
voltage threshold
Clock oscillator falls below the clock monitor minimum
frequency
Acceleration
Parity of the EPROM bits becomes odd in number.
The fault latch can be reset by a rising edge on the self-test
input pin, unless one (or more) of the fault conditions continues
to exist.
Figure 2. Simplified Transducer Physical Model versus
Transducer Physical Model
SPECIAL FEATURES
Filtering
The Motorola accelerometers contain an onboard 4-pole
switched capacitor filter. A Bessel implementation is used
because it provides a maximally flat delay response (linear
phase) thus preserving pulse shape integrity. Because the filter
is realized using switched capacitor techniques, there is no
requirement for external passive components (resistors and
capacitors) to set the cut-off frequency.
MMA2301D
4
Motorola Sensor Device Data
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Freescale Semiconductor, Inc.
BASIC CONNECTIONS
Pinout Description
PCB Layout
STATUS
P1
N/C
N/C
N/C
ST
1
2
3
4
5
6
7
16
15
14
13
12
11
10
9
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
ST
P0
V
V
SS
V
A/D In
OUT
R
1 kΩ
0.1 µF
C
C 0.01 µF
C 0.1 µF
V
V
SS
DD
OUT
DD
C 0.1 µF
STATUS
V
V
V
SS
RH
V
DD
8
Pin Descriptions
Power Supply
Pin No.
Pin Name
N/C
Description
Leave unconnected.
1 thru 3
Figure 4. Recommend PCB Layout for Interfacing
Accelerometer to Microcontroller
4
ST
Logic input pin used to initiate self-test.
Output voltage of the accelerometer.
Logic output pin to indicate fault.
The power supply ground.
5
V
OUT
NOTES:
6
STATUS
•
•
•
Use a 0.1 µF capacitor on VDD to decouple the power
source.
7
8
V
V
SS
DD
Physical coupling distance of the accelerometer to the
microcontroller should be minimal.
Place a ground plane beneath the accelerometer to reduce
noise, the ground plane should be attached to all of the open
ended terminals shown in Figure 4
Use an RC filter of 1 kΩ and 0.01 µF on the output of the
accelerometer to minimize clock noise (from the switched
capacitor filter circuit).
The power supply input.
9 thru 13
Trim pins
Used for factory trim. Leave
unconnected.
14 thru 16
—
No internal connection. Leave
unconnected.
•
•
•
•
PCB layout of power and ground should not couple power
supply noise.
Accelerometer and microcontroller should not be a high
current path.
A/D sampling rate and any external power supply switching
frequency should be selected such that they do not interfere
with the internal accelerometer sampling frequency. This
will prevent aliasing errors.
6
MMA2301D
ST
V
Status
DD
Logic
Input
4
8
R1
1 kΩ
5
Output
Signal
V
V
OUT
DD
C1
0.1 µF
C2
0.01 µF
7 V
SS
Figure 3. SOIC Accelerometer with Recommended
Connection Diagram
Motorola Sensor Device Data
MMA2301D
For More Information On This Product,
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5
Freescale Semiconductor, Inc.
Dynamic Acceleration Sensing Direction
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
Acceleration of the package
in the +X direction (center
plate moves in the −X
direction) will result in an
increase in the output.
Activation of Self Test
moves the center plate in
the −X direction, resulting in
an increase in the output.
+x
−x
16-Pin SOIC Package
N/C pins are recommended to be left FLOATING
Top View
Static Acceleration Sensing Direction
8
7
6
5
4
3
2 1
Direction of Earth's gravity field.*
9 10 11 12 13 14 15 16
Front View
Side View
* When positioned as shown, the Earth's gravity will result in a positive 1g output.
MMA2301D
6
Motorola Sensor Device Data
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Freescale Semiconductor, Inc.
PACKAGE DIMENSIONS
A
A
G/2
2 PLACES, 16 TIPS
G
NOTES:
1. ALL DIMENSIONS ARE IN MILLIMETERS.
0.15 T A
B
2. INTERPRET DIMENSIONS AND TOLERANCES
PER ASME Y14.5M, 1994.
16
9
3. DIMENSIONS "A" AND "B" DO NOT INCLUDE
MOLD FLASH OR PROTRUSIONS. MOLD FLASH
OR PROTRUSIONS SHALL NOT EXCEED 0.15
PER SIDE.
4. DIMENSION "D" DOES NOT INCLUDE DAMBAR
PROTRUSION. PROTRUSIONS SHALL NOT
CAUSE THE LEAD WIDTH TO EXCEED 0.75.
B
B
P
1
8
MILLIMETERS
16X D
DIM MIN
MAX
10.45
7.60
M
0.13
T
A
B
A
B
C
D
F
10.15
7.40
3.30
0.35
0.76
3.55
0.49
1.14
R X 45˚
G
J
K
M
P
R
1.27 BSC
0.25
0.10
0˚
0.32
0.25
7˚
J
C
10.16
0.25
10.67
0.75
0.1
M
K
F
SEATING
PLANE
T
CASE 475-01
ISSUE B
16 LEAD SOIC
MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS
Surface mount board layout is a critical portion of the total
design. The footprint for the surface mount packages must be
the correct size to ensure proper solder connection interface
between the board and the package. With the correct footprint,
the packages will self-align when subjected to a solder reflow
process. It is always recommended to design boards with a
solder mask layer to avoid bridging and shorting between solder
pads.
0.050 in.
1.27 mm
0.380 in.
9.65 mm
0.024 in.
0.610 mm
0.080 in.
2.03 mm
Figure 5. Footprint SOIC-16 (Case 475-01)
Motorola Sensor Device Data
MMA2301D
7
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