MOTOROLA MMA6231Q 10g dual axis micromachined accelerometer Datasheet

Freescale Semiconductor, Inc.
MOTOROLA
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SEMICONDUCTOR TECHNICAL DATA
±10g Dual Axis
Micromachined Accelerometer
MMA6231Q
MMA6233Q
The MMA6200 series of low cost capacitive micromachined accelerometers feature signal conditioning, a 1-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.
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Low Noise
Low Cost
Low Power
2.7 V to 3.6 V Operation
6mm x 6mm x 1.98 mm QFN
Integral Signal Conditioning with Low Pass Filter
Linear Output
Ratiometric Performance
Self-Test
Robust Design, High Shocks Survivability
MMA6230Q Series: X-Y AXIS SENSITIVITY
MICROMACHINED ACCELEROMETER
±10 g
Bottom View
Typical Applications
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Pedometer
Appliance Control
Impact Monitoring
Vibration Monitoring and Recording
Position & Motion Sensing
Freefall Detection
Smart Portable Electronics
16 LEAD QFN
CASE 1477-01
Pin Assignment
Device Name
IDD
Case No.
Package
N/C
YOUT
Bandwidth
Response
N/C
ORDERING INFORMATION
XOUT
Top View
16 15 14 13
MMA6231Q
300 Hz
1.2 mA
1477-01
QFN-16, Tube
N/C
1
12 ST
MMA6231QR2
300 Hz
1.2 mA
1477-01
QFN-16,Tape & Reel
N/C
MMA6233Q
900 Hz
2.2 mA
1477-01
QFN-16, Tube
MMA6233QR2
900 Hz
2.2 mA
1477-01
QFN-16,Tape & Reel
10
N/C
VSS 4
9
N/C
REV 0
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5
6
7
8
N/C
N/C
N/C
11
N/C
2
VDD 3
N/C
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Features
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VDD
G-CELL
SENSOR
ST
SELF-TEST
X-INTEGRATOR
X-GAIN
CONTROL LOGIC &
EEPROM TRIM CIRCUITS
Y-INTEGRATOR
X-FILTER
OSCILLATOR
Y-GAIN
Y-FILTER
X-TEMP
COMP
XOUT
CLOCK GEN
Y-TEMP
COMP
YOUT
VSS
Freescale Semiconductor, Inc...
Figure 1. Simplified Accelerometer Functional Block Diagram
MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.)
Rating
Symbol
Value
Unit
Maximum Acceleration (all axis)
gmax
±2000
g
Supply Voltage
VDD
-0.3 to +3.6
V
Drop Test1
Ddrop
1.2
m
Tstg
-40 to +125
°C
Storage Temperature Range
NOTE:
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
2000 V 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.
Motorola Sensor Device Data
MMA6200 Series
2
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Operating Characteristics
Unless otherwise noted: -20°C < TA < 85°C, 3.0 V < VDD < 3.6 V, Acceleration = 0g, Loaded output1
Characteristic
Symbol
Min
Typ
Max
Unit
VDD
2.7
3.3
3.6
V
MMA6231Q
IDD
—
1.2
1.5
mA
MMA6233Q
IDD
—
2.2
3.0
mA
Operating Temperature Range
TA
-20
—
+85
°C
Acceleration Range
gFS
—
10
—
g
VOFF
1.485
1.65
1.815
V
Operating Range2
Supply Voltage3
Supply Current
Output Signal
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Zero g (TA = 25°C, VDD = 3.3 V)4
Zero g
Sensitivity (TA = 25°C, VDD = 3.3 V)
Sensitivity
VOFF, TA
—
2.0
—
mg/°C
S
111
120
129
mV/g
S, TA
—
0.015
—
%/°C
f_3dB
—
300
—
Hz
Bandwidth Response
MMA6231Q
MMA6233Q
f_3dB
—
900
—
Hz
NLOUT
-1.0
—
+1.0
% FSO
MMA6231Q RMS (0.1 Hz – 1 kHz)
nRMS
—
0.7
—
mVrms
MMA6233Q RMS (0.1 Hz – 1 kHz)
nRMS
—
0.6
—
MMA6231Q
nPSD
—
50
—
MMA6233Q
nPSD
—
30
—
Output Response
gST
2.0
—
—
g
Input Low
VIL
—
—
0.3 VDD
V
Nonlinearity
Noise
Power Spectral Density RMS (0.1 Hz – 1 kHz)
ug/√Hz
Self-Test
Input High
VIH
0.7 VDD
—
VDD
V
RPO
43
57
71
kΩ
tST
—
2.0
—
ms
VFSO
VSS +0.25
—
VDD -0.25
V
CL
—
—
100
pF
ZO
—
50
300
Ω
MMA6231Q
tRESPONSE
—
2.0
—
ms
MMA6233Q
tRESPONSE
—
0.7
—
ms
Pull-Down
Resistance5
Response Time6
Output Stage Performance
Full-Scale Output Range (IOUT = 200 µA)
Capacitive Load Drive7
Output Impedance
Power-Up Response Time
Mechanical Characteristics
VZX, YX, ZY
-5.0
—
+5.0
% FSO
Transverse Sensitivity8
NOTES:
1. For a loaded output, the measurements are observed after an RC filter consisting of a 1.0 kΩ resistor and a 0.1 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 2.7 and 3.6 V, 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. For negative acceleration, the output will decrease below VDD/2.
5. The digital input pin has an internal pull-down resistance to prevent inadvertent self-test initiation due to external board level leakages.
6. Time for the output to reach 90% of its final value after a self-test is initiate.
7. Preserves phase margin (60°) to guarantee output amplifier stability.
8. A measure of the device’s ability to reject an acceleration applied 90° from the true axis of sensitivity.
Motorola Sensor Device Data
MMA6200 Series
3
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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 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
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.
The g-cell plates form two back-to-back capacitors
(Figure 2). 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 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
SPECIAL FEATURES
Filtering
These Motorola accelerometers contain an onboard
single-pole switched capacitor filter. 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 allowing the
verification of the mechanical and electrical integrity of
the accelerometer at any time before or after installation.
A fourth plate is used in the g-cell as a self-test plate.
When a logic high input to the self-test pin is applied, 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
ASIC and a proportional output voltage results. This procedure assures both the mechanical (g-cell) and electronic sections of the accelerometer are functioning.
Motorola accelerometers include fault detection circuitry and a fault latch. Parity of the EEPROM bits becomes odd in number.
Self-test is disabled when EEPROM parity error occurs.
Ratiometricity
Ratiometricity simply means the output offset voltage
and sensitivity will scale linearly with applied supply voltage. That is, as supply voltage is increased, 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.
Figure 2. Simplified Transducer Physical Model
Motorola Sensor Device Data
MMA6200 Series
4
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16 15 14 13
N/C
12 ST
1
10
N/C
VSS 4
9
N/C
5
6
7
8
N/C
N/C
N/C
11
N/C
2
VDD 3
N/C
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N/C
Pin
Name
1, 5 - 7, 13, 16
N/C
14
15
XOUT
R
1 kΩ
YOUT
VSS
VDD
R
1 kΩ
A/D IN
C 0.1 µF
A/D IN
C 0.1 µF
C 0.1 µF
VSS
C 0.1 µF
VDD
VRH
C 0.1 µF
POWER SUPPLY
Figure 3. Pinout Description
Pin No.
P0
ST
MICROCONTROLLER
N/C
YOUT
N/C
XOUT
Top View
ACCELEROMETER
BASIC CONNECTIONS
Description
Figure 5. Recommend PCB Layout for Interfacing
Accelerometer to Microcontroller
Notes:
No internal connection.
Leave unconnected.
1. Use 0.1 µF capacitor on VDD to decouple the power
source.
YOUT
Output voltage of the accelerometer. Y
Direction.
2. Physical coupling distance of the accelerometer to
the microcontroller should be minimal.
XOUT
Output voltage of the accelerometer. X
Direction.
3. Flag underneath package is connected to ground.
3
VDD
Power supply input.
4
VSS
The power supply ground.
2, 8 - 11
N/C
Used for factory trim.
Leave unconnected.
5. Use an RC filter with 1.0 kΩ and 0.1 µF on the
outputs of the accelerometer to minimize clock noise
(from the switched capacitor filter circuit).
12
ST
Logic input pin used to initiate
self-test.
6. PCB layout of power and ground should not couple
power supply noise.
4. 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.
7. Accelerometer and microcontroller should not be a
high current path.
VDD
MMA6200Q
Series
3
VDD
0.1 µF
YOUT
14
1 kΩ
0.1 µF
4
12
8. 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 (16 kHz for Low IDD and 52 kHz
for Standard IDD for the sampling frequency). This
will prevent aliasing errors.
VSS
XOUT 15
ST
Logic
Input
1 kΩ
0.1 µF
Figure 4. Accelerometer with Recommended Connection
Motorola Sensor Device Data
MMA6200 Series
5
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DYNAMIC ACCELERATION
Top View
+Y
16 15 14 13
Freescale Semiconductor, Inc...
+X
1
12
2
11
3
10
4
9
5
6
7
-X
8
-Y
16-Pin QFN Package
STATIC ACCELERATION
Top View
Direction of Earth's gravity field.*
XOUT @ 0g = 1.65V
XOUT @ 0g = 1.65V
YYOUT
@ -1g = 1.53V
OUT @ -1g = 0.85V
XOUT @
@ +1g == 2.45V
XOUT
1.77V
YOUT@
@0g
0g== 1.65V
1.65V
YOUT
OUT @
XXOUT
@-1g
-1g==0.85V
1.53V
OUT @ 0g = 1.65V
YY
OUT @ 0g = 1.65V
OUT @
XXOUT
@0g0g= =1.65V
1.65V
YOUT @@
+1g
= 2.45V
+1g
= 1.77V
Y
OUT
* When positioned as shown, the Earth's gravity will result in a positive 1g output
Motorola Sensor Device Data
MMA6200 Series
6
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6
PIN 1
INDEX AREA
M
A
0.1 C
2X
0.15 C
G
0.08 C
1.98+0.1
5
6
(0.203)
(0.102)
M
0.15 C
SEATING PLANE
VIEW ROTATED 90˚ CLOCKWISE
4
0.1 C A B
16X
4.24
4.04
EXPOSED DIE
ATTACH PAD
13
(45˚)
0.1
DETAIL M
PIN 1 INDEX
16
DETAIL M
12
4.24
4.04
1
0.5
NOTES:
1. ALL DIMENSIONS ARE IN MILLIMETERS.
2. INTERPRET DIMENSIONS AND TOLERANCES
PER ASME Y14.5M, 1994.
3. THIS DIMENSION APPLIES TO METALLIZED
TERMINAL AND IS MEASURED BETWEEN 0.25MM
AND 0.30MM FROM TERMINAL TIP.
4. THIS DIMENSION REPRESENTS TERMINAL FULL
BACK FROM PACKAGE EDGE UP TO 0.1MM IS
ACCEPTABLE.
5. COPLANARITY APPLIES TO THE EXPOSED HEAT
SLUG AS WELL AS THE TERMINAL.
6. RADIUS ON TERMINAL IS OPTIONAL.
0.1 C A B
9
4
12X
8
16X
1
5
0.63
0.43
16X
VIEW M-M
0.60
0.40
0.1
M
C A B
0.05
M
C
3
CASE 1477-01
ISSUE O
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.
6.0
0.55
4.25
9
8
13
12
1.00
5
16
0.50
6.0
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C
DETAIL G
2X
B
(0.5)
(1)
1
Pin 1 ID (non metallic)
Motorola Sensor Device Data
4
Solder areas
MMA6200 Series
7
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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
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MMA6231Q
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