MOTOROLA
Freescale Semiconductor, Inc.
Order this document
by MMA1220D/D
SEMICONDUCTOR TECHNICAL DATA
MMA1220D
Low G
Micromachined Accelerometer
The MMA series of silicon capacitive, micromachined accelerometers
features signal conditioning, a 4–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.
Features
MMA1220D: Z AXIS SENSITIVITY
MICROMACHINED
ACCELEROMETER
± 8g
Freescale Semiconductor, Inc...
• Integral Signal Conditioning
• Linear Output
• Ratiometric Performance
16
• 4th Order Bessel Filter Preserves Pulse Shape Integrity
9
• Calibrated Self–test
1
• Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status
8
• Transducer Hermetically Sealed at Wafer Level for Superior Reliability
16 LEAD SOIC
CASE 475–01
• Robust Design, High Shock Survivability
Typical Applications
• Vibration Monitoring and Recording
Pin Assignment
• Appliance Control
• Mechanical Bearing Monitoring
N/C
• Computer Hard Drive Protection
N/C
• Computer Mouse and Joysticks
N/C
ST
• Virtual Reality Input Devices
VOUT
STATUS
VSS
VDD
• Sports Diagnostic Devices and Systems
ORDERING INFORMATION
Device
Temperature Range
MMA1220D
–40 to +85°C
Case No.
Package
Case 475–01
SOIC–16
16
15
14
13
12
11
10
1
2
3
4
5
6
7
8
9
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM
VDD
G–CELL
SENSOR
ST
SELF–TEST
INTEGRATOR
GAIN
CONTROL LOGIC &
EPROM TRIM CIRCUITS
FILTER
OSCILLATOR
TEMP
COMP
VOUT
CLOCK GEN.
VSS
STATUS
Figure 1. Simplified Accelerometer Functional Block Diagram
REV 0
Motorola Sensor Device Data
Motorola, Inc. 2001
For More Information On This Product,
Go to: www.freescale.com
1
Freescale Semiconductor, Inc.
MMA1220D
MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.)
Symbol
Value
Unit
Powered Acceleration (all axes)
Rating
Gpd
1500
g
Unpowered Acceleration (all axes)
Gupd
2000
g
Supply Voltage
VDD
–0.3 to +7.0
V
Ddrop
1.2
m
Tstg
– 40 to +105
°C
Drop Test(1)
Storage Temperature Range
NOTES:
1. Dropped onto concrete surface from any axis.
Freescale Semiconductor, Inc...
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
2
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.
For More Information On This Product,
Go to: www.freescale.com
Motorola Sensor Device Data
Freescale Semiconductor, Inc.
MMA1220D
OPERATING CHARACTERISTICS
(Unless otherwise noted: –40°C
v TA v +85°C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1))
Characteristic
Operating Range(2)
Supply Voltage(3)
Supply Current
Operating Temperature Range
Acceleration Range
Freescale Semiconductor, Inc...
Output Signal
Zero g (VDD = 5.0 V)(4)
Zero g
Sensitivity (TA = 25°C, VDD = 5.0 V)(5)
Sensitivity
Bandwidth Response
Nonlinearity
Noise
RMS (10 Hz – 1 kHz)
Clock Noise (without RC load on output)(6)
Self–Test
Output Response
Input Low
Input High
Input Loading(7)
Response Time(8)
Symbol
Min
Typ
Max
Unit
VDD
IDD
TA
gFS
4.75
3.0
40
—
5.00
5.0
—
8.0
5.25
6.0
+85
—
V
mA
°C
g
VOFF
VOFF,V
S
SV
f –3dB
NLOUT
2.25
0.45 VDD
237.5
46.5
150
1.0
2.5
0.50 VDD
250
50
250
—
2.75
0.55 VDD
262.5
53.5
350
+3.0
V
V
mV/g
mV/g/V
Hz
% FSO
nRMS
nCLK
—
—
—
2.0
6.0
—
mVrms
mVpk
0.3 VDD
0.3 VDD
VDD
200
10
V
V
V
µA
ms
DVST
*
*
VIL
VIH
IIN
tST
0.2 VDD
VSS
0.7 VDD
50
—
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
fmin
50
—
260
kHz
tDELAY
VFSO
CL
ZO
—
VSS+0.25
—
—
2.0
—
—
300
—
VDD 0.25
100
—
*
ms
V
pF
Ω
VXZ,YZ
fPKG
—
—
—
10
5.0
—
% FSO
kHz
Clock Monitor Fail Detection Frequency
Output Stage Performance
Electrical Saturation Recovery Time(9)
Full Scale Output Range (IOUT = 200 µA)
Capacitive Load Drive(10)
Output Impedance
Mechanical Characteristics
Transverse Sensitivity(11)
Package Resonance
*
*
—
—
—
100
2.0
*
*
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 VDD/2 and for negative acceleration the output will decrease below VDD/2.
5. The device is calibrated at 20g, 100 Hz. Sensitivity limits apply to 0 Hz acceleration.
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.
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 by a rising edge on self–test, unless a fault condition continues to exist.
*
^
Motorola Sensor Device Data
For More Information On This Product,
Go to: www.freescale.com
3
Freescale Semiconductor, Inc.
MMA1220D
Freescale Semiconductor, Inc...
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 processes (masking and etching). It can be modeled as two
stationary plates with a moveable plate in–between. The
center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2).
When the center plate deflects, the distance from it to one
fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is
a measure of acceleration.
The g–cell plates form two back–to–back capacitors
(Figure 3). As the center plate moves with acceleration, the
distance between the plates changes and each capacitor’s
value will change, (C = Aε/D). Where A is the area of the
plate, ε is the dielectric constant, and D is the distance
between the plates.
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.
Acceleration
Figure 2. Transducer
Physical Model
4
Figure 3. Equivalent
Circuit 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.
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 = 1/2 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.
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.
Status
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
• 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.
For More Information On This Product,
Go to: www.freescale.com
Motorola Sensor Device Data
Freescale Semiconductor, Inc.
PCB Layout
BASIC CONNECTIONS
Pinout Description
ST
VOUT
STATUS
Freescale Semiconductor, Inc...
VSS
VDD
16
15
14
13
12
11
10
N/C
9
N/C
ACCELEROMETER
N/C
N/C
STATUS
N/C
N/C
N/C
N/C
N/C
N/C
Description
1 thru 3
VSS
Redundant connections to the internal
VSS and may be left unconnected.
4
ST
Logic input pin used to initiate self–
test.
5
VOUT
STATUS
Output voltage of the accelerometer.
8
9 thru 13
Trim pins
Used for factory trim.
Leave unconnected.
14 thru 16
—
No internal connection.
Leave unconnected.
VDD
1 kΩ
C 0.01 µF
C 0.1 µF
VRH
VSS
C 0.1 µF
VDD
0.1 µF
Figure 5. Recommended PCB Layout for Interfacing
Accelerometer to Microcontroller
NOTES:
The power supply ground.
• Use a 0.1 µF capacitor on VDD to decouple the power
source.
The power supply input.
6
MMA1220D
LOGIC
INPUT
VSS
A/D IN
R
Logic output pin used to indicate fault.
VSS
VDD
VDD
VOUT
P0
POWER SUPPLY
Pin Name
7
ST
C
Pin No.
6
P1
MICROCONTROLLER
1
2
3
4
5
6
7
8
N/C
MMA1220D
4 ST
8 VDD
VOUT
C1
0.1 µF
7 VSS
5
• 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 5.
STATUS
R1
1 kΩ
OUTPUT
SIGNAL
C2
0.01 µF
Figure 4. SOIC Accelerometer with Recommended
Connection Diagram
Motorola Sensor Device Data
• 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).
• 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.
For More Information On This Product,
Go to: www.freescale.com
5
Freescale Semiconductor, Inc.
MMA1220D
ACCELERATION SENSING DIRECTIONS
DYNAMIC ACCELERATION
N/C
N/C
N/C
+g
[ VOUT > 2.75 ]
ST
VOUT
STATUS
VSS
VDD
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
16–Pin SOIC Package
Freescale Semiconductor, Inc...
–g
N/C pins are recommended to be left FLOATING
[ VOUT < 2.75 ]
STATIC ACCELERATION
Direction of Earth’s gravity field.*
+1g
VOUT = 2.75V
0g
0g
VOUT = 2.50V
VOUT = 2.50V
–1g
VOUT = 2.25V
* When positioned as shown, the Earth’s gravity will result in a positive 1g output
6
For More Information On This Product,
Go to: www.freescale.com
Motorola Sensor Device Data
Freescale Semiconductor, Inc.
MMA1220D
PACKAGE DIMENSIONS
–A–
16
9
P 8 PL
0.13 (0.005)
–B–
1
M
T A
B
M
M
8
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER
SIDE.
5. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
PROTRUSION SHALL BE 0.13 (0.005) TOTAL IN
EXCESS OF D DIMENSION AT MAXIMUM
MATERIAL CONDITION.
D 16 PL
0.13 (0.005)
M
T A
M
B
M
R
X 45 _
K
J
Freescale Semiconductor, Inc...
C
–T–
SEATING
PLANE
K
G
F
M
DIM
A
B
C
D
F
G
J
K
M
P
R
MILLIMETERS
MIN
MAX
10.15
10.45
7.40
7.60
3.30
3.55
0.35
0.49
0.76
1.14
1.27 BSC
0.25
0.32
0.10
0.25
0_
7_
10.16
10.67
0.25
0.75
INCHES
MIN
MAX
0.400
0.411
0.292
0.299
0.130
0.140
0.014
0.019
0.030
0.045
0.050 BSC
0.010
0.012
0.004
0.009
0_
7_
0.400
0.420
0.010
0.029
CASE 475–01
ISSUE A
16 LEAD SOIC
Motorola Sensor Device Data
For More Information On This Product,
Go to: www.freescale.com
7
Freescale Semiconductor, Inc...
MMA1220D
Freescale Semiconductor, Inc.
Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or
guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the
application or use of any product 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 under its patent rights nor the rights of others. Motorola products are
not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications
intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where
personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application,
Buyer shall indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs,
damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated
with such unintended or unauthorized use, even if such claim alleges that Motorola was negligent regarding the design or manufacture of the
part. Motorola and
are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal Opportunity/Affirmative Action Employer.
How to reach us:
USA / EUROPE / Locations Not Listed: Motorola Literature Distribution;
P.O. Box 5405, Denver, Colorado 80217. 1–303–675–2140 or 1–800–441–2447
Technical Information Center: 1–800–521–6274
JAPAN: Motorola Japan Ltd.; SPS, Technical Information Center, 3–20–1,
Minami–Azabu. Minato–ku, Tokyo 106–8573 Japan. 81–3–3440–3569
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://www.motorola.com/semiconductors/
8
◊
For More Information On This Product,
Go to: www.freescale.com
Motorola Sensor Device Data
MMA1220D/D
