MOTOROLA MMA1210D

Freescale Semiconductor, Inc.
MOTOROLA
Order number: MMA1210D
Rev 1, 1/2004
SEMICONDUCTOR TECHNICAL DATA
Surface Mount
Micromachined Accelerometer
MMA1210D
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.
MMA1210D: Z AXIS SENSITIVITY
MICROMACHINED
ACCELEROMETER
±100g
Freescale Semiconductor, Inc...
Features
•
•
•
•
•
•
•
•
Integral Signal Conditioning
Linear Output
Ratiometric Performance
4th 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
16 LEAD SOIC
CASE 475-01
PIN ASSIGNMENT
Typical Applications
•
•
Vibration Monitoring and Recording
Impact Monitoring
N/C
N/C
N/C
ST
VOUT
ORDERING INFORMATION
Device
Temperature
Range
Case No.
Package
MMA1210D
– 40 to +125°C
Case 47--01
SOIC-16
MMA1210DR2
– 40 to +125°C
Case 475-01
SOIC-16, Tape & Reel
STATUS
VSS
VDD
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
VDD
G-CELL
SENSOR
ST
SELF-TEST
INTEGRATOR
GAIN
CONTROL LOGIC &
EPROM TRIM CIRCUITS
FILTER
OSCILLATOR
TEMP
COMP
CLOCK GEN.
STATUS
Figure 1. Simplified Accelerometer Functional Block Diagram
REV 1
This document contains certain information on a new product.
Specifications and information herein are subject to change without notice.
© Motorola, Inc. 2004
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VOUT
VSS
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
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Maximum Ratings (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.)
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
Tstg
–40 to +125
°C
Storage Temperature Range
Freescale Semiconductor, Inc...
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
2
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.
Surface Mount Micromachined Accelerometer
MMA1210D
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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
VDD
4.75
3.0
–40
—
5.00
—
—
112.5
5.25
6.0
+125
—
V
mA
C
g
VOFF
VOFF,v
S
SV
f–3dB
NLOUT
2.35
0.46 VDD
19
3.72
360
–1.0
2.5
0.50 VDD
20.0
4.0
400
—
2.65
0.54 VDD
21
4.28
440
1.0
V
V
mV/g
mV/g/V
Hz
% FSO
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
55
VSS
0.7 × VDD
–30
—
75
—
—
–100
2.0
95
0.3 × 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 –.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
—
0.25
—
—
0.2
—
—
300
—
VDD–0.25
100
—
ms
V
pF
Ω
VXZ,YZ
fPKG
—
—
—
10
5.0
—
% FSO
kHz
Operating Range (2)
Supply Voltage (3)
Supply Current
Operating Temperature Range
Acceleration Range
IDD
TA
gFS
Output Signal
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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
Noise
RMS (0.1-1 kHz)
Power Spectral Density
Clock Noise (without RC load on output)(6)
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 Impedence
Mechanical Characteristics
Transverse Sensitivity(11)
Package Resonance
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 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 µs, unless a fault condition continues to exist.
MOTOROLA
Surface Mount Micromachined Accelerometer
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MMA1210D
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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
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
Figure 2. Transducer
Physical Model
Figure 3. Equivalent
Circuit Model
SPECIAL FEATURES
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.
Filtering
The Motorola accelerometers contain an onboard 4pole switched capacitor filter. A Bessel implementation is
4
Surface Mount Micromachined Accelerometer
MMA1210D
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Freescale Semiconductor, Inc.
ACCELEROMETER
BASIC CONNECTIONS
Pinout Description
Freescale Semiconductor, Inc...
N/C
N/C
N/C
ST
VOUT
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
STATUS
VSS
VDD
STATUS
P1
ST
VOUT
VSS
VDD
N/C
N/C
N/C
N/C
N/C
N/C
N/C
N/C
P0
A/D IN
R
1 kΩ
C 0.01 µF
C 0.1 µF
MICROCONTROLLER
The fault latch can be reset by a rising edge on the selftest input pin, unless one (or more) of the fault conditions
continues to exist.
VSS
C 0.1 µF
VDD
VRH
C 0.1 µF
POWER SUPPLY
Figure 5. Recommended PCB Layout for Interfacing
Accelerometer to Microcontroller
Pin No.
Pin Name
1 thru 3
—
Leave unconnected.
4
ST
Logic input pin used to
initiate self-test.
• Use a 0.1 µF capacitor on VDD to decouple the power
source.
5
VOUT
Output voltage of the
accelerometer.
• Physical coupling distance of the accelerometer to the
microcontroller should be minimal.
6
STATUS
Logic output pin to
indicate fault.
7
VSS
The power supply
ground.
• 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.
8
VDD
The power supply input.
9 thru 13
Trim pins
14 thru 16
—
LOGIC
INPUT
Used for factory trim.
Leave unconnected.
No internal connection.
Leave unconnected.
MMA1210D
VDD
Description
6
4 ST
8 VDD
C1
0.1 µF
7 VSS
VOUT 5
R1
1 kΩ
STATUS
NOTES:
• 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.
OUTPUT
SIGNAL
C2
0.01 µF
Figure 4. SOIC Accelerometer with
Recommended Connection Diagram
MOTOROLA
Surface Mount Micromachined Accelerometer
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MMA1210D
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Dynamic Acceleration Sensing Direction
+Z
Acceleration of the package
in the +Z direction (center
plate moves in the −Z
direction) will result in an
increase in the output.
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Activation of Self test moves
the center plate in the −Z
direction, resulting in an
increase in the output.
-Z
Side View
Static Acceleration Sensing Direction
Direction of Earth's gravity field.*
Side View
* When positioned as shown, the Earth's gravity will result in a positive 1g output.
6
Surface Mount Micromachined Accelerometer
MMA1210D
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PACKAGE DIMENSIONS
A
A
G/2
2 PLACES, 16 TIPS
G
NOTES:
1. ALL DIMENSIONS ARE IN MILLIMETERS.
2. INTERPRET DIMENSIONS AND TOLERANCES
PER ASME Y14.5M, 1994.
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.
0.15 T A B
16
9
B
P
1
B
8
16X
D
0.13
M
T A B
Freescale Semiconductor, Inc...
R
X 45˚
J
C
0.1
K
T
MILLIMETERS
DIM MIN
MAX
A
10.15
10.45
B
7.40
7.60
C
3.30
3.55
D
0.35
0.49
F
0.76
1.14
G
1.27 BSC
J
0.25
0.32
K
0.10
0.25
M
0˚
7˚
P
10.16
10.67
R
0.25
0.75
F
M
SEATING
PLANE
CASE 475-01
ISSUE B
16 LEAD SOIC
DATE 05/17/01
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
0.380 in.
9.65 mm
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
0.024 in.
0.610 mm
0.080 in.
2.03 mm
Figure 6. Footprint SOIC-16 (Case 475-01)
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Surface Mount Micromachined Accelerometer
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MMA1210D
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Information in this document is provided solely to enable system and software implementers to use Motorola products. There are no express or implied
copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document.
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 the Stylized M Logo are registered in the US Patent and Trademark Office. All other product or service names are the property of their
respective owners.
© Motorola, Inc. 2004
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852-26668334
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MMA1210D