MOTOROLA
SEMICONDUCTOR TECHNICAL DATA Order Number: MMA2301 D
Rev. 2, 06/2004
© Motorola, Inc. 2004
REV 2
Surface Mount Micromachined
Accelerometer
The MMA series of silicon capacitive, micromachined accelerometers features
signal conditioning, a four-pole low pass filter and temperature compensation.
Zero-g offse t ful l s cale s p an and fil ter c ut-o f f are fa ctory set and require no e xte rnal
devices. A full system self-test capability verifies system functionality.
Features
• Integ ral Sign al Cond itioning
• Linear Output
• Ratiometric Performance
• Fourth Or der Bessel Filter Preserves Pulse Shape Integrity
• Calibrated Self-test
• Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status
• Trans ducer He rme tic al ly Seal ed at Wafer Level for Superior Reliabi li ty
• Robust Design, High Shocks Survivability
Typical Applications
• Vibration Monitoring and Recording
• Impact Monitoring
ORDERING INFORMATION
Figure 1. Simplified Accelerometer Functional Block Diagram
Device Temperature
Range Package
MMA2301D – 40 to +125°C SOIC-16
MMA2301DR2 – 40 to +125°C SOIC-16, Tape & Reel
MMA2301D
16 LEAD SOIC
CASE 475-01
MMA2301 D: X-AXIS SENSITIV ITY
MICROMACHINED
ACCELEROMETER
±200g
PIN ASSIGNMENT
N/C
N/C
N/C
ST
VOUT
STATUS
VSS
VDD
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
G-Cell
Sensor Integrator Gain Filter Temp
Self-Test Control Logic &
EPROM
Trim Circuits Clock
Gen.
Oscillator
VDD
VOUT
VSS
ST
Status
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MMA2301D Motorola Sensor Device Data
2
Maximum Ratings
(Maximum ratings are the limits to which the device can be exposed without causing permanent damage.)
NOTES:
1. Dropped onto concrete s urface from any axis.
ELECTRO STATIC DISCHARGE (ESD)
WARNING: This device is sensitive to electrostatic
discharge.
Although the Motorola accelerometers contain internal 2kV
ESD prote ction circ uitry, e xtra precau tion m ust be t aken b y the
user to prot ect the chip from ESD. A charg e of ov er 2 000 vol t s
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.
Rating Symbol Value Unit
Powered Acceleration (all axes) Gpd 1500 g
Unpowered Acceleration (all axes) Gupd 2000 g
Supply Voltage VDD –0.3 to +7.0 V
Drop Test (1) Ddrop 1.2 m
Storage Temperature Range Tstg –40 to +125 °C
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Motorola Sensor Device Data MMA2301D
3
NOTES:
1. For a loaded output the measurements are observed after an RC filter consisting of a 1 kΩ resi st or and a 0.01 µF capacitor to gr ou nd.
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 VDD/2 and for negative acceleration the output will decrease below VDD/2.
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 mar gin (60°) to guarantee output amplifier stability.
11. A meas ure 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.
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
Operating Range(2)
Supply Voltage(3)
Supply Current
Operating Temperature Range
Acceleration Range
VDD
IDD
TA
gFS
4.75
3.0
-40
—
5.0
—
—
225
5.25
6.0
+125
—
V
mA
°C
g
Output Signal
Zero g (TA = 25°C, VDD = 5.0 V)(4)
Zero g
Sensitivity (TA = 25°C, VDD = 5.0 V)(5)
Sensitivity
Bandwidth Response
Nonlinearity
VOFF
VOFF,V
S
SV
f-3dB
NLOUT
2.4
0.46 VDD
9.5
1.86
360
-1.0
2.5
0.50 VDD
10.0
2.0
400
—
2.6
0.54 VDD
10.5
2.14
440
1.0
V
V
mV/g
mV/g/V
Hz
% FSO
Noise
RMS (.01-1 kHz)
Power Spectral Density
Clock Noise (without RC load on output)(6)
nRMS
nPSD
nCLK
—
—
—
—
110
2.0
2.8
—
—
mVrms
µV/(Hz1/2)
mVpk
Self-Test
Output Response
Input Low
Input High
Input Loading(7)
Response Time(8)
gST
VIL
VIH
IIN
tST
24
VSS
0.7 x VDD
-30
—
30
—
—
-100
2.0
36
0.3 x VDD
VDD
-260
10
g
V
V
µA
ms
Status(12)(13)
Output Low (Iload = 100 µA)
Output High (Iload = 100 µA) VOL
VOH
—
VDD -0.8 —
—0.4
—V
V
Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V
Clock Monitor Fail Detection Frequency fmin 50 — 260 kHz
Output Stage Performance
Electrical Saturation Recovery Time(9)
Full Scale Output Range (IOUT = 200 µA)
Capacitive Load Drive(10)
Output Impedance
tDELAY
VFSO
CL
ZO
—
0.25
—
—
0.2
—
—
300
—
VDD -0.25
100
—
ms
V
pF
Ω
Mechanical Characteristics
Transverse Sensitivity(11)
Package Resonance VXZ,YZ
fPKG
—
——
10 5.0
—% FSO
kHz
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MMA2301D Motorola Sensor Device Data
4
PRINCIPLE OF OPERATION
The Motorola accelerometer is a surface-micromachined
integrated-circuit accelerometer.
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.
The g-cell is a mechanical structure formed from
semiconductor materials (polysilicon) using semiconductor
proc esses (maski ng and etch ing). It c an be model ed as a se t of
beams a tta ched to a mov able centr al mass t hat move b etween
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
dist ance 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.
The g-cell plates form two back-to-back capacitors
(Figure 2). As the central mass moves with acceleration, the
dist anc e betw e en the bea ms chan ge and each capac ito r' s
value will change, (C = NAε/D). Where A is the area of the
facing side of the beam, ε is the dielectric constan t, D is the
dist anc e betw e en the bea ms , and N is the numbe r of beams .
The CMOS ASIC uses switched capacitor techniques to
measur e the g-cell capac itors and extract the accel eration data
from the dif feren ce be twee n the two ca pac itors. The AS IC al so
signal conditions and filters (switched capacitor) the signal,
providing a high level output voltage that is ratiometric and
proportional to acceleration.
Figure 2. Simplified Transducer Physical Model versus
Transd ucer Physi cal 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) th us preserving puls e shape integrit y . Because the fil ter
is realized using switched capacitor techniques, there is no
requirement for external passive components (resistors and
capacitors) to set the cut-off frequency.
Self-Test
The sensor provides a self-test feature that allows the
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 = 1/2AV2/d2) causes the center plate to deflect. The
result ant deflec tion is m easured by the a cceleromete r's control
ASIC and a prop ortiona l outp ut vol tag e resu lts . This procedure
assures that both the mechanical (g-cell) and electronic
sections of the accelerometer are functioning.
Ratiometricity
Ratiometricity simply means that the output offset voltage
and sensitivity will scale linearly with applied supply voltage.
That is, as you increase su pply voltage the sensitivity a nd offset
inc rease linea rly; as supply vo ltage d ecrea ses, 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 erro rs in
the analog to digital conversion process.
Status
Motorola acceleromet ers 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
• 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.
Acceleration
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Motorola Sensor Device Data MMA2301D
5
BASIC CONNECTIONS
Pinout Description
Figure 3. SOIC Accelerometer with Recommended
Connection Diagram
Figure 4. Recommend PCB Layout for Interfacing
Accelerometer to Microcontroller
NOTES:
• Use a 0.1 µF capacitor on VDD to decouple the power
source.
• Physical coupling distance of the accelerometer to the
microcontroller should be minimal.
• Place a gro und p lane beneat h the accel erome ter to redu ce
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 switc hed
capacitor filter circuit).
• PCB layout of power and ground should not couple power
supply noise.
• Accelerometer and microcontroller should not be a high
current path.
• A/D sa mplin g rate and any externa l power suppl y switch ing
frequency should be selected such that they do not interfere
with the internal accelerometer sampling frequency. This
will prevent aliasing errors.
Pin Descriptions
Pin No. Pin Name Description
1 thru 3 N/C Leave unconnected.
4 ST Logic input pin used to initiate self-test.
5V
OUT Output voltage of the accelerometer.
6 STATUS Logic output pin to indicate fault.
7V
SS The power supply ground.
8V
DD The power supply input.
9 thru 13 Trim pins Used for factory trim. Leave
unconnected.
14 thru 16 — No internal connection. Leave
unconnected.
10
11
12
13
14
15
16
9
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
8
7
6
5
4
3
2
1
N/C
N/C
N/C
ST
VOUT
STATUS
VDD
VSS
MMA2301D
ST
VDD
VSS
VOUT Output
Signal
R1
1 kΩ
5
C2
0.01 µF
4
8
7
Logic
Input
VDD
C1
0.1 µF
6Status
P0
A/D In
VRH
VSS
VDD
ST
VOUT
VSS
VDD
0.01 µF
1 kΩ
0.1 µF
Power Supply
R
C
0.1 µF
P1
STATUS
Microcontroller
Accelerometer
C
C
C
0.1 µF
PCB Layout
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MMA2301D Motorola Sensor Device Data
6
* When positioned as shown, the Earth's gravity will result in a positive 1g output.
Dynamic Acceleration Sensing Direction
10 11 12 13 14 15 16
87654321
9
Direction of Earth's gravity field.*
Front Vi ew Side View
Static Acceleration Sensing Direction
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
−x
+x
16-Pin SOIC Package
N/C pins are recommended to be left FLOATING
Top View
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.
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Motorola Sensor Device Data MMA2301D
7
PACKAGE DIMENSIONS
MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS
Surface mount board layout is a critical portion of the total
design . The footprint for the surfac e m oun t p ac k age s m us t be
the correct size to ensure proper solder connection interface
betwee n the board and th e package. Wit h the correct foo tprint,
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.
DATE 05/17/01
CASE 475-01
ISSUE B
C
K
SEATING
PLANE
T
0.1
18
16 9
P
2 PLACES, 16 TIPS
D16X
A0.15 BT
A
M
0.13 BT
A
B
A
B
G
G/2
MILLIMETERS
DIM
A
B
C
D
F
G
J
K
M
P
R
MIN
10.15
7.40
3.30
0.35
0.76
0.25
0.10
0˚
10.16
0.25
MAX
10.45
7.60
3.55
0.49
1.14
1.27 BSC
0.32
0.25
7˚
10.67
0.75
RX 45˚
J
FM
NOTES:
1.
2.
3.
4.
ALL DIMENSIONS ARE IN MILLIMETERS.
INTERPRET DIMENSIONS AND TOLERANCES
PER ASME Y14.5M, 1994.
DIMENSIONS "A" AND "B" DO NOT INCLUDE
MOLD FLASH OR PROTRUSIONS. MOLD FLASH
OR PROTRUSIONS SHALL NOT EXCEED 0.15
PER SIDE.
DIMENSION "D" DOES NOT INCLUDE DAMBAR
PROTRUSION. PROTRUSIONS SHALL NOT
CAUSE THE LEAD WIDTH TO EXCEED 0.75.
16 LEAD SOIC
Figure 5. Footprint SOIC-16 (Case 475-01)
0.380 in.
9.65 mm
0.050 in.
1.27 mm
0.024 in.
0.610 mm
0.080 in.
2.03 mm
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HOW TO REACH US:
USA/EUROPE/LOCATIONS NOT LISTED:JAPAN: Motorola Japan Ltd.; SPS, Technical Information Center
Motorola Literature Distribution 3-20-1 Minami-Azabu. Minato-ku, Tokyo 106-8573, Japan
P.O. Box 5405, Denver, Colorado 80217 81-3-3440-3569
1-800-521-6274 or 480-768-2130 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; Silicon Harbour Centre
2 Dai King Street, Tai Po Industrial Estate, Tai Po, N.T., Hong Kong
852-26668334
HOME PAGE: http://motorola.com/semiconduc tors
MMA2301D
Information in this document is provided solely to enable system and softw are implementers to use Motorola products. There are no express or implied
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Motorola reserves the ri ght to mak e changes withou t further no tice to any prod ucts herein. Moto rola makes no warranty, represe ntation o r gu arante e
regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the ap plic a tion or use o f any pr odu ct
or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be
provided in Motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating
parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. Motorola does not convey any license
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© Motorola, Inc. 2004
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