LIS3L02AS4
MEMS INERTIAL SENSOR: 3-Axis - 2g/6g LINEAR ACCELEROMETER
1
Features
2.4V TO 3.6V SINGLE SUPPLY OPERATION LOW POWER CONSUMPTION 2g/6g USER SELECTABLE FULL-SCALE 0.5mg RESOLUTION OVER 100Hz BANDWIDTH EMBEDDED SELF TEST AND POWER DOWN OUTPUT VOLTAGE, OFFSET AND SENSITIVITY RATIOMETRIC TO THE SUPPLY VOLTAGE HIGH SHOCK SURVIVABILITY LEAD FREE AND ECOPACK COMPATIBLE
Figure 1. Package
SO24
Table 1. Order Codes
Part Number E-LIS3L02AS4 E-LIS3L02AS4TR Package SO24 SO24 Finishing Tube Tape & Reel
2
Description
The LIS3L02AS4 is a low-power three axes linear 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 to design a dedicated circuit which is trimmed to better match the sensing element characteristics. The LIS3L02AS4 has a user selectable full scale of Figure 2. Block Diagram
X+ Y+ Z+
2g, 6g and it is capable of measuring accelerations over a bandwidth of 1.5KHz 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 LIS3L02AS4 is available in plastic SMD package and it is specified over an extended temperature range of -40C to +85C. The LIS3L02AS4 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
Routx CHARGE AMPLIFIER S/H
Voutx
a
ZYX-
MUX
DEMUX
Routy S/H
Vouty
Routz S/H
Voutz
SELF TEST
REFERENCE
TRIMMING CIRCUIT
CLOCK
December 2005
Rev. 2 1/14
LIS3L02AS4
Table 2. Pin Description
N 1 to 5 6 7 8 9 10 11 12 13 14-15 16 17 18 19 to 24 Pin NC GN D Vd d Vouty ST Voutx PD Voutz FS Reser ved Reser ved Reser ved Reser ved NC Internally not connected 0V supply Power supply Output Voltage Self Test (Logic 0: normal mode; Logic 1: Self-test) Output Voltage Power Down (Logic 0: normal mode; Logic 1: Power-Down mode) Output Voltage Full Scale selection (Logic 0: 2g Full-scale; Logic 1: 6g Full-scale) Leave unconnected or connect to Vdd Connect to Vdd or ground Leave unconnected or connect to Vdd Leave unconnected or connect to ground Internally not connected Function
Figure 3. Pin Connection (Top view)
NC NC DIRECTION OF THE DETECTABLE ACCELERATIONS
X
13
NC NC NC NC NC NC
Reserved Reserved Reserved Reserved Reserved FS
NC NC NC GND
Y
1
Vdd Vouty
Z
ST Voutx PD Voutz
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Table 3. Mechanical Characteristics1 (Temperature range -40C to +85C). All the parameters are specified @ Vdd =3.3V, T=25C unless otherwise noted
Symbol Ar So SoDr Voff OffDr NL Parameter Acceleration Range Sensit ivit y
4 3
Test Condition FS pin connected to GND FS pin connected to Vdd Full-scale = 2g Full-scale = 6g Delta from +25C T = 25C Delta from +25C Best fit straight line Full-scale = 2g X, Y axis Best fit straight line; Full-scale = 2g Z axis
Min. 1.8 5.4 Vdd/510% Vdd/1510%
Typ.2 2.0 6.0 Vdd/5 Vdd/15 0.01
Max.
Unit g g
Vdd/5+10% Vdd/15+10%
V/g V/g %/C
Sensitivity Change Vs Temperature Zero-g Level4 Zero-g level Change Vs Temperature Non Linearity5
Vdd/2-10%
Vdd/2 1.1 0.3
Vdd/2+10%
V mg / C
1.5
% FS
0.6
2
% FS
CrossAx Cross-Axis6 An Vt Acceleration Noise Density Self test Output Voltage Change7,8,9 Vdd=3.3V; Full-scale = 2g T = 25C Vdd=3.3V Full-scale = 2g X axis T = 25C Vdd=3.3V Full-scale = 2g Y axis T = 25C Vdd=3.3V Full-scale = 2g Z axis Fres Sensing Element Resonance Frequency10 Operating Temperature Range Product Weight all axes -20
2 50 - 50
4
% g/ H z
-100
mV
20
50
100
mV
20
50
100
mV
1.5
K Hz
Top Wh
-40 0.6
+85
C gram
Notes: 1. The product is factory calibrated at 3.3V. The device can be powered from 2.4V to 3.6V. Voff, So and Vt parameters will vary with supply voltage. 2. Typical specifications are not guaranteed 3. Verified 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. Contribution to the measuring output of an 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.
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Table 4. Electrical Characteristics1 (Temperature range -40C to +85C) All the parameters are specified @ Vdd =3.3V, T=25C unless otherwise noted
Symbol Vdd Idd Parameter Supply Voltage Supply Current mean value PD pin connected to GND rms value PD pin connected to Vdd Logic 0 level Logic 1 level Rout Cload Ton Output Impedance Capacitive Load Drive3 Cload in F 0 2 .2 80 320 550*Cload+0.3 110 Test Condition Min. 2.4 Typ.2 3.3 0.85 Max. 3.6 1.5 Unit V mA
IddPdn
Supply Current in Power Down Mode Self Test Input
2
5
A
Vst
0.8 Vdd 140
V V k pF ms
Turn-On Time at exit from Power Down mode
Notes: 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
3
Absolute Maximum Rating
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 5. Absolute Maximum Rating
Symbol Vdd Vin APOW Supply Voltage Input Voltage on any control pin (FS, PD, ST) Acceleration (Any axis, Powered, Vdd=3.3V) R a tings Maximum Value -0.3 to 7 -0.3 to Vdd +0.3 3000g for 0.5 ms 10000g for 0.1 ms AUNP Acceleration (Any axis, Not powered) 3000g for 0.5 ms 10000g for 0.1 ms TSTG ESD Storage Temperature Range Electrostatic Discharge Protection -40 to +125 2 (HBM) 200 (MM) 1500 (CDM) C kV V V Unit V V
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
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3.1 Terminology 3.1.1 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. 3.1.2 Zero-g level Describes the actual output signal if there is no acceleration present. A sensor in a steady state on an horizontal surface will measure 0g in X axis and 0g in Y axis whereas the Z axis will measure +1g. 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. 3.1.3 Self Test Self Test allows to test the mechanical and electric part of the sensor, allowing the seismic mass to be moved by means of an electrostatic test-force. The Self Test function is off when the ST pin is connected to GND. When the ST pin is tied at Vdd an actuation force is applied to the sensor, simulating a definite input acceleration. In this case the sensor outputs will exhibit a voltage change in their DC levels which is related to the selected full scale and depending on the Supply Voltage through the device sensitivity. When ST is activated, the device output level is given by the algebraic sum of the signals produced by the acceleration acting on the sensor and by the electrostatic test-force. If the output signals change within the amplitude specified inside Table 3, than the sensor is working properly and the parameters of the interface chip are within the defined specification. 3.1.4 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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4
Functionality
The LIS3L02AS4 is a high performance, low-power, analog output three axes linear accelerometer packaged in a SO24 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. 4.1 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. 4.2 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 (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 4.3 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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5
Application Hints
Figure 4. LIS3L02AS4 Electrical Connection
Vdd
10F GND
100nF GND GN D
LIS3L02AS4
(top view)
ST GND
DIRECTION OF THE DETECTABLE ACCELERATIONS
X
13
PD
FS Optional Cload z Optional Vout X Cload x Optional Cload y Vout Y Vout Z
Y
1
Z
Digital signals
Power supply decoupling capacitors (100nF ceramic + 10F Al) should be placed as near as possible to the device (common design practice). The LIS3L02AS4 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 cutoff frequency ( f t ) of the external filters is: 1 f t = ----------------------------------------------------------------------2 R o u t C l o a d ( x, y, z ) Taking in account that the internal filtering resistor (Rout) has a nominal value equal to 110 k , the equation for the external filter cut-off frequency may be simplified as follows: 1.45 F f t = ------------------------------------- [ H z ] 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 Cload(x, y, z) is required in any case.
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Table 6. Filter Capacitor Selection, Cload (x,y,z). Capacitance Value Choose.
Cut-off frequency 1 Hz 10 Hz 50 Hz 100 Hz 200 Hz 500 Hz Capacitor value 1500nF 150nF 30 nF 15 nF 6.8 nF 3 nF
5.1 Soldering information The SO24 package is lead free qualified for soldering heat resistance according to JEDEC J-STD-020C. 5.2 Output response vs orientation Figure 5. Output response vs orientation
Top Bottom
X=0.99V (-1g) Y=1.65V (0 g) Z=1.65V (0g)
X=1.65V (0g) Y=1.65V (0g) Z=0.99V (-1g)
Top Bottom
X=1.65V (0g) Y=1.65V (0g) Z=2.31V (+1g)
X=1.65V (0g) Y=2.31V (+1g) Z=1.65V (0g)
TOP VIEW
X=1.65V (0g) Y=0.99V (-1g) Z=1.65V (0g)
X=2.31V (+1g) Y=1.65V (0g) Z=1.65V (0g)
Earth's Surface
Figure 5 refers to LIS3L02AS4 device powered at 3.3V
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LIS3L02AS4
6
Typical performance Characteristics
6.1 Mechanical Characteristics at 25C. Figure 6. X axis Zero g Level at 3.3V
20 18 16 Percent of parts (%)
Figure 9. X axis Sensitivity at 3.3V
25
20 Percent of parts (%)
14 12 10 8 6 4 2 0 1.55 1.6 1.65 Zerog Level (V) 1.7 1.75
15
10
5
0 0.62
0.63
0.64
0.65 0.66 0.67 Sensitivity (V/g)
0.68
0.69
0.7
Figure 7. Y axis Zero g Level at 3.3V
20 18 16 Percent of parts (%)
Figure 10. Y axis Sensitivity at 3.3V
25
20 Percent of parts (%)
14 12 10 8 6 4 2 0 1.55 1.6 1.65 Zerog Level (V) 1.7 1.75
15
10
5
0 0.62
0.63
0.64
0.65 0.66 0.67 Sensitivity (V/g)
0.68
0.69
0.7
Figure 8. Z axis Zero g Level at 3.3V
20 18 16 Percent of parts (%)
Figure 11. Z axis Sensitivity at 3.3V
25
20 Percent of parts (%)
14 12 10 8 6 4 2 0 1.55 1.6 1.65 Zerog Level (V) 1.7 1.75
15
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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6.2 Mechanical Characteristics derived from measurement in the -40C to +85Ctemperature range Figure 12. X axis Zero g Level Change Vs. Temperature
35 30 25 20 15 10 5 0 1
Figure 15. X axis Sensitivity Change Vs. Temperature
45 40 35
Percent of parts (%)
Percent of parts (%) 0.5 0 0.5 1 Zerog level change (mg/deg. C) 1.5 2
30 25 20 15 10 5
0 0.03
0.02
0.01 0 0.01 Sensitivity Change(%/deg. C)
0.02
Figure 13. Y axis Zero g Level Change Vs. Temperature
50 45 40 Percent of parts (%)
Figure 16. Y axis Sensitivity Change Vs. Temperature
50 45 40 Percent of parts (%) 35 30 25 20 15 10 5
35 30 25 20 15 10 5 0 1 0.5 0 0.5 0g level change (mg/deg. C) 1
0 0.03
0.02
0.01 0 0.01 Sensitivity Change (%/deg. C)
0.02
Figure 14. Z axis Zero g Level Change Vs. Temperature
30
Figure 17. Z axis Sensitivity Change Vs. Temperature
40 35 30
25 Percent of parts (%) Percent of parts (%) 1 0 1 2 0g level change (mg/deg. C) 3 4
20
25 20 15 10
15
10
5
5 0 0.05
0
0.04
0.03 0.02 0.01 0 0.01 Sensitivity Change (%/deg. C)
0.02
0.03
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6.3 Electrical Characteristics at 25C Figure 18. Noise density at 3.3V (X,Y axes)
35 30 16 Percent of parts (%) Percent of parts (%) 25 20 15 10 5 0 18 14 12 10 8 6 4 2 20 22 24 26 28 Noise density (ug/sqrt(Hz)) 30 32 0 0.4 0.6 0.8 1 current consumption (mA) 1.2 1.4
Figure 20. Current consumption at 3.3V
20 18
Figure 19. Noise density at 3.3V (Z axis)
25
Figure 21. Current consumption in power down mode at 3.3V
30
20 Percent of parts (%) Percent of parts (%)
25
20
15
15
10
10
5
5
0 20
30
40 50 60 Noise density (ug/sqrt(Hz))
70
80
0 1.2
1.3
1.4 1.5 1.6 current consumption (uA)
1.7
1.8
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7
Package Information
In order to meet environmental requirements, ST offers these devices in ECOPACK packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. Figure 22. SO24 Mechanical Data & Package Dimensions
mm DIM. M IN. A A1 B C D (1) E e H h L k ddd 10.0 0.25 0.40 2.35 0.10 0.33 0.23 15.20 7.40 1.27 10.65 0.75 1.27 0.394 0.010 0.016 TYP. MAX . 2.65 0.30 0.51 0.32 15.60 7.60 MIN. 0.093 0.004 0.013 0.009 0.598 0.291 0.050 0.419 0.030 0.050 TYP. MA X. 0.104 0.012 0.200 0.013 0.614 0.299 Weight: 0.60gr inch
OUTLINE AND MECHANICAL DATA
0 (min.), 8 (max.) 0.10 0.004
(1) "D" dimension does not include mold flash, protusions or gate burrs. Mold flash, protusions or gate burrs shall not exceed 0.15mm per side.
SO24
0070769 C
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8
Revision History
Table 7. Revision History
Date Februar y 2004 1-Dec-2005 Revision 1 2 First issue Changed from Product preview to Datasheet maturity. Added Typical performance Characteristics section. Description of Changes
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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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