LIS2L02AQ3
MEMS INERTIAL SENSOR: 2-axis - 2g/6g LINEAR ACCELEROMETER
Features
2.4V TO 5.25V SINGLE SUPPLY OPERATION LOW POWER CONSUMPTION 2g/6g USER SELECTABLE FULL-SCALE 0.3mg RESOLUTION OVER 100Hz BANDWIDTH EMBEDDED SELF TEST AND POWER DOWN OUTPUT VOLTAGE, OFFSET AND SENSITIVITY RATIOMETRIC TO THE SUPPLY VOLTAGE HIGH SHOCK SURVIVABILITY ECO-PACK COMPLIANT
QFN-44
to design a dedicated circuit which is trimmed to better match the sensing element characteristics. The LIS2L02AQ3 has a user selectable full scale of 2g, 6g and it is capable of measuring accelerations over a bandwidth of 1.5 KHz for all axes. The device bandwidth may be reduced by using external capacitances. A self-test capability allows to check the mechanical and electrical signal path of the sensor. The LIS2L02AQ3 is available in plastic SMD package and it is specified over an extended temperature range of -40C to +85C. The LIS2L02AQ3 belongs to a family of products suitable for a variety of applications: Mobile terminals Gaming and Virtual Reality input devices Free-fall detection for data protection Antitheft systems and Inertial Navigation Appliance and Robotics.
Description
The LIS2L02AQ3 is a low-power 2-axis linear capacitive accelerometer that includes a sensing element and an IC interface able to take the information from the sensing element and to provide an analog signal to the external world. The sensing element, capable of detecting the acceleration, is manufactured using a dedicated process developed by ST to produce inertial sensors and actuators in silicon. The IC interface is manufactured using a standard CMOS process that allows high level of integration
Order codes
Par t number LIS2L02AQ3 LIS2L02AQ3TR Temp range, C -40C to +85C -40C to +85C Package QFN-44 QFN-44 Packing Tray Tape & Reel
July 2005
CD00059664
Rev 1 1/17
www.st.com
17
LIS2L02AQ3
C onte nts
1 Block Diagram & Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 1.2 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2
Mechanical and Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 2.2 2.3 2.4 Mechanical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3
Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1 3.2 3.3 Sensing element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 IC Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Factor y calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4
Application hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Soldering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5
Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1 5.2 5.3 Mechanical Characteristics at 25C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Mechanical Characteristics derived from measurement in the -40C to +85C temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Electrical characteristics at 25C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6 7
Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
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1 Block Diagram & Pin Description
1
1.1
Block Diagram & Pin Description
Block diagram
Figure 1. Block Diagram
X+ Y+ CHARGE AMPLIFIER S/H
Routx Voutx
a
YX-
MUX
DEMUX
Routy Vouty S/H
SELF TEST
REFERENCE
TRIMMING CIRCUIT
CLOCK
1.2
Pin Description
Figure 2. Pin Connection (Top view)
NC NC NC NC NC NC NC NC NC NC NC
1 Y
NC NC NC GND Vdd Vouty
NC NC NC NC
LIS2L02AQ3
NC Reserved Reserved Reserved NC NC Reserved
X
ST Voutx NC
DIRECTION OF THE DETECTABLE ACCELERATIONS
NC NC
FS
Reserved
Reserved
Reserved
Reserved
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Reserved
NC
NC
PD
NC
NC
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1 Block Diagram & Pin Description
LIS2L02AQ3
Table 1.
Pin # 1 to 3 4 5 6 7 8 9-13 14 15 16 17-18 19 20 21 22-23 24-25 26 27 28 29-44
Pin description
Pin Name NC G ND Vdd Vouty ST Voutx NC PD NC FS Reser ved Reser ved Reser ved NC Reser ved NC Reser ved Reser ved Reser ved NC Inter nally not connected 0V supply Power supply Output Voltage, y-channel Self Test (Logic 0: normal mode; Logic 1: Self-test) Output Voltage, x-channel Inter nally not connected Power Down (Logic 0: normal mode; Logic 1: Power-Down mode) Inter nally not connected Full Scale selection (Logic 0: 2g Full-scale; Logic 1: 6g Full-scale) Leave unconnected Leave unconnected Leave unconnected Inter nally not connected Leave unconnected Inter nally not connected Connect to Vdd or GND Leave unconnected or connect to Vdd Leave unconnected or connect to GND Inter nally not connected Function
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2 Mechanical and Electrical Specifications
2
2.1
Table 2.
Mechanical and Electrical Specifications
Mechanical Characteristics
Mechanical Characteristics1 (Temperature range -40C to +85C) All the parameters are specified @ Vdd =3.3V, T = 25C unless otherwise noted.
Parameter Test Condition FS pin connected to GND FS pin connected to Vdd Full-scale = 2g Full-scale = 6g Delta from +25C T = 25C Vdd/2-6% Min. 1.8 5.4 Vdd/510% Vdd/1510% Typ.2 2.0 6.0 Vdd/5 Vdd/15 0.01 Vdd/2 0.2 0.3 2 Vdd=3.3V; Full-scale = 2g 30 1.5 4 Vdd/2+6% Vdd/5+10% Vdd/15+10% Max. Unit g g V/g V/g %/C V mg/C % FS % g ----------Hz
Symbol
Ar
Acceleration Range
3
So
Sensitivity4 Sensitivity Change Vs Temperature Zero-g Level4
SoDr Voff OffDr NL
Zero-g Level Change Vs Delta from +25C Temperature Non Linearity5 Best fit straight line Full-scale = 2g
CrossAx Cross-Axis6 An Acceleration Noise Density
Vt
T = 25C Vdd=3.3V Full-scale = 2g Self Test Output Voltage X axis Change7,8,9 T = 25C Vdd=3.3V Full-scale = 2g Y axis
20
50
100
mV
-20
-50
-100
mV
Fres Top Wh
Sensing Element all axes Resonance Frequency10 Operating Temperature Range Product Weight
1.5 -40 0.2 +85
KHz C gram
Note: 1 The product is factory calibrated at 3.3V. The device can be powered from 2.4V to 5.25V. Voff, So and Vt parameters will vary with supply voltage. 2 Typical specifications are not guaranteed
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2 Mechanical and Electrical Specifications
LIS2L02AQ3
3 Guaranteed by wafer level test and measurement of initial offset and sensitivity 4 Zero-g level and sensitivity are essentially ratiometric to supply voltage 5 Guaranteed by design 6 Contr ibution to the measuring output of the inclination/acceleration along any perpendicular axis 7 Self test "output voltage change" is defined as Vout(Vst=Logic1)-Vout(Vst=Logic0) 8 Self test "output voltage change" varies cubically with supply voltage 9 When full-scale is set to 6g, self-test "output voltage change" is one third of the specified value 10 Minimum resonance frequency Fres=1.5KHz. Sensor bandwidth=1/(2**110K*Cload) with Cload>1nF.
2.2
Table 3.
Electrical Characteristics
Electrical Characteristics1 (Temperature range -40C to +85C) All the parameters are specified @ Vdd =3.3V, T=25C unless otherwise noted
Parameter Supply Voltage Supply Current Supply Current in Power Down Mode Self Test Input Logic 1 level Rout Output Impedance Capacitive Load Drive3 Tur n-On Time at Exit From Power Down Mode Operating Temperature Range Cload in F -40 2.2 80 320 550*Cload+0.3 +8 5 110 Vdd 140 V k pF ms C mean value PD pin connected to GND r ms value PD pin connected to Vdd Logic 0 level Vst 0 Test Condition M i n. 2.4 Typ.2 3.3 0.85 Max. 5.25 1.5 U ni t V mA
Symbol Vdd Idd
IddPdn
2
5 0.8
A V
Clo a d Ton Top
Note: 1 The product is factory calibrated at 3.3V 2 Typical specifications are not guaranteed 3 Minimum resonance frequency Fres=1.5KHz. Sensor bandwidth=1/(2**110K*Cload) with Cload>1nF
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2 Mechanical and Electrical Specifications
2.3
Absolute maximum ratings
Stresses above those listed as "absolute maximum ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device under these conditions is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. Table 4.
Symbol Vdd Vin APOW Supply voltage Input Voltage on Any Control pin (FS, PD, ST) Acceleration (Any axis, Powered, Vdd=3.3V) 10000g for 0.1 ms 3000g for 0.5 ms Acceleration (Any axis, Not powered) 10000g for 0.1 ms Storage Temperature Range -40 to +125 2KV HBM ESD Electrostatic Discharge Protection 200V MM 1500V CDM C
Absolute maximum ratings
Ratings Maximum Value -0.3 to 7 -0.3 to Vdd +0.3 3000g for 0.5 ms Unit V V
AUNP TSTG
This is a Mechanical Shock sensitive device, improper handling can cause permanent damages to the part This is an ESD sensitive device, improper handling can cause permanent damages to the part
2.4
Terminology
Sensitivity describes the gain of the sensor and can be determined by applying 1g acceleration to it. As the sensor can measure DC accelerations this can be done easily by pointing the axis of interest towards the center of the earth, note the output value, rotate the sensor by 180 degrees (point to the sky) and note the output value again thus applying 1g acceleration to the sensor. Subtracting the larger output value from the smaller one and dividing the result by 2 will give the actual sensitivity of the sensor. This value changes very little over temperature (see sensitivity change vs. temperature) and also very little over time. The Sensitivity Tolerance describes the range of Sensitivities of a large population of sensors. Zero-g level describes the actual output signal if there is no acceleration present. A sensor in a steady state on a horizontal surface will measure 0g in X axis and 0g in Y axis. The output is ideally for a 3.3V powered sensor Vdd/2 = 1650mV. A deviation from ideal 0-g level (1650mV in this case) is called Zero-g offset. Offset of precise MEMS sensors is to some extend a result of stress to the sensor and therefore the offset can slightly change after mounting the sensor onto a printed circuit board or exposing it to extensive mechanical stress. Offset changes little over temperature - see "Zero-g level change vs. temperature" - the Zero-g level of an individual sensor is very stable over lifetime. The Zero-g level tolerance describes the range of zero-g levels of a population of sensors.
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2 Mechanical and Electrical Specifications
LIS2L02AQ3
Self Test allows to test the mechanical and electrical part of the sensor. By applying a digital signal to the ST input pin an internal reference is switched to a certain area of the sensor and creates a defined deflection of the moveable structure. The sensor will generate a defined signal and the interface chip will perform the signal conditioning. If the output signal changes with the specified amplitude than the sensor is working properly and the parameters of the interface chip are within the defined specifications. Output impedance describes the resistor inside the output stage of each channel. This resistor is part of a filter consisting of an external capacitor of at least 320pF and the internal resistor. Due to the high resistor level only small, inexpensive external capacitors are needed to generate low corner frequencies. When interfacing with an ADC it is important to use high input impedance input circuitries to avoid measurement errors. Note that the minimum load capacitance forms a corner frequency beyond the resonance frequency of the sensor. For a flat frequency response a corner frequency well below the resonance frequency is recommended. In general the smallest possible bandwidth for an particular application should be chosen to get the best results.
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3 Functionality
3
Functionality
The LIS2L02AQ3 is a high performance, low-power, analog output 2-axis linear accelerometer packaged in a QFN package. The complete device includes a sensing element and an IC interface able to take the information from the sensing element and to provide an analog signal to the external world.
3.1
Sensing element
A proprietary process is used to create a surface micro-machined accelerometer. The technology allows to carry out suspended silicon structures which are attached to the substrate in a few points called anchors and are free to move in the direction of the sensed acceleration. To be compatible with the traditional packaging techniques a cap is placed on top of the sensing element to avoid blocking the moving parts during the moulding phase of the plastic encapsulation. When an acceleration is applied to the sensor the proof mass displaces from its nominal position, causing an imbalance in the capacitive half-bridge. This imbalance is measured using charge integration in response to a voltage pulse applied to the sense capacitor. At steady state the nominal value of the capacitors are few pF and when an acceleration is applied the maximum variation of the capacitive load is up to 100fF.
3.2
IC Interface
In order to increase robustness and immunity against external disturbances the complete signal processing chain uses a fully differential structure. The final stage converts the differential signal into a single-ended one to be compatible with the external world. The signals of the sensing element are multiplexed and fed into a low-noise capacitive charge amplifier that implements a Correlated Double Sampling system (CDS) at its output to cancel the offset and the 1/f noise. The output signal is de-multiplexed and transferred to three different S&Hs, one for each channel and made available to the outside. The low noise input amplifier operates at 200 kHz while the three S&Hs operate at a sampling frequency of 66 kHz. This allows a large oversampling ratio, which leads to in-band noise reduction and to an accurate output waveform. All the analog parameters (zero-g level, sensitivity and self-test) are ratiometric to the supply voltage. Increasing or decreasing the supply voltage, the sensitivity and the offset will increase or decrease almost linearly. The self test voltage change varies cubically with the supply voltage.
3.3
Factory calibration
The IC interface is factory calibrated for sensitivity (So) and Zero-g level (Voff). The trimming values are stored inside the device by a non volatile structure. Any time the device is turned on, the trimming parameters are downloaded into the registers to be employed during the normal operation. This allows the user to employ the device without further calibration.
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4 Application hints
LIS2L02AQ3
4
Figure 3.
Application hints
LIS2L02AQ3 Electrical Connection
Vdd
44
34
Vdd
33
1
10F GND
100nF GND ST
GND
LIS2L02AQ3
(top view)
23res
12
GND
1 Y
GND
11
22
X
FS res
res res res
PD
res
DIRECTION OF THE DETECTABLE ACCELERATIONS
Optional Vout X Cload x Optional Cload y Vout Y Digital signals
Power supply decoupling capacitors (100nF ceramic or polyester + 10F Aluminum) should be placed as near as possible to the device (common design practice). The LIS2L02AQ3 allows to band limit Voutx, Vouty and Voutz through the use of external capacitors. The re-commended frequency range spans from DC up to 1.5 KHz. In particular, capacitors must be added at output pins to implement low-pass filtering for antialiasing and noise reduction. The equation for the cut-off frequency (ft) of the external filters is: 1 f t = --------------------------------------------------------------2 R o u t C l o a d ( x, y, z ) Taking into account that the internal filtering resistor (Rout) has a nominal value equal to 110kOhm, the equation for the external filter cut-off frequency may be simplified as follows: 1.45 F f t = ---------------------------------C l o a d ( x, y, z ) The tolerance of the internal resistor can vary typically of 20 % within its nominal value of 110k; thus the cut-off frequency will vary accordingly. A minimum capacitance of 320 pF for Cf(x, y, z) is required in any case.
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Table 5.
4 Application hints
Filter Capacitor Selection, Cf (x,y,z). Capacitance value approximated closest commercial available.
Cut-off frequency 1 Hz 10 Hz 20 Hz 50 Hz 100 Hz 200 Hz 500 Hz Capacitor value 1500 nF 150 nF 68 nF 30 nF 15 nF 6.8 nF 3 nF
4.1
Soldering information
The QFN44 package is lead free and green package qualified for soldering heat resistance according to JEDEC J-STD-020C. Land pattern and soldering recommendations are available upon request.
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5 Typical performance characteristics
LIS2L02AQ3
5
5.1
Typical performance characteristics
Mechanical Characteristics at 25C
x-axis 0-g level at 3.3V Figure 5.
15
Figure 4.
15
y-axis 0-g level at 3.3V
Percent of parts (%)
Percent of parts (%)
10
10
5
5
0 1.55
1.6
1.65 0 g LEVEL (V)
1.7
1.75
0 1.55
1.6
1.65 0 g LEVEL (V)
1.7
1.75
Figure 6.
20 18 16
x-axis sensitivity at 3.3V
Figure 7.
15
y-axis sensitivity at 3.3V
Percent of parts (%)
Percent of parts (%)
14 12 10 8 6 4 2 0 0.62 0.63 0.64 0.65 0.66 0.67 sensitivity (V/g) 0.68 0.69 0.7
10
5
0 0.62
0.63
0.64
0.65 0.66 0.67 sensitivity (V/g)
0.68
0.69
0.7
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5 Typical performance characteristics
5.2
Mechanical Characteristics derived from measurement in the -40C to +85C temperature range
x-axis 0-g level change Vs temperature Figure 9.
40 35 30
Percent of parts (%)
Figure 8.
45 40 35
Percent of parts (%)
y-axis 0-g level change Vs temperature
30 25 20 15 10 5 0 1 0.8 0.6 0.4 0.2 0 0.2 Zero g level change (mg/C) 0.4 0.6
25 20 15 10 5 0 1
0.5 0 0.5 Zero g level change (mg/C)
1
Figure 10. x-axis sensitivity change Vs temperature
30
Figure 11. y-axis sensitivity change Vs temperature
30
25
25
Percent of parts (%)
Percent of parts (%)
20
20
15
15
10
10
5
5
0 20
15
10 5 sensitivity change (%/C)
0 x 10
5
3
0 20
15
10 5 0 sensitivity change (%/C)
5 x 10
3
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5 Typical performance characteristics
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5.3
Electrical characteristics at 25C
Figure 13. Current consumption at 3.3V
20 18
Figure 12. Noise density at 3.3V
35 30
16
Percent of parts (%)
Percent of parts (%)
20 22 24 26 28 Noise density (ug/sqrt(Hz)) 30 32
25 20 15 10 5
14 12 10 8 6 4 2
0 18
0 0.4
0.6
0.8 1 current consumption (mA)
1.2
1.4
Figure 14. Current consumption in power down mode at 3.3V
30
25
Percent of parts (%)
20
15
10
5
0 1.2
1.3
1.4 1.5 1.6 current consumption (uA)
1.7
1.8
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6 Package Information
6
Package Information
Figure 15. QFN-44 Mechanical Data & Package Dimensions
mm DIM. MIN. A A1 b D E e J K L P 5.04 5.04 0.38 0.48 45 REF 1.70 0.19 0.20 0.25 7.0 7.0 0.50 5.24 5.24 0.58 0.198 0.198 0.015 0.019 45 REF TYP. 1.80 MAX. 1.90 0.21 0.30 MIN. 0.067 0.007 0.008 0.01 0.276 0.276 0.020 0.206 0.206 0.023 TYP. 0.071 MAX. 0.075 0.008 0.012 inch
OUTLINE AND MECHANICAL DATA
QFN-44 (7x7x1.8mm) Quad Flat Package No lead
M
G
M
N
34 44 44 1
33
1
DETAIL "N"
23 11
22
12
DETAIL G
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SEATING PLANE
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7 Revision history
LIS2L02AQ3
7
Revision history
Date 15-July-2005 Revision 1 First issue. Cha nge s
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Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners 2005 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America www.st.com
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