STMICROELECTRONICS LIS2L02AQ

LIS2L02AQ
INERTIAL SENSOR:
2Axis - 2g/6g LINEAR ACCELEROMETER
1
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■
■
■
■
■
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2
Figure 1. Package
FEATURES
2.4V TO 5.25V SINGLE SUPPLY OPERATION
0.5mg RESOLUTION OVER 100Hz BW
2g/6g USER SELECTABLE FULL-SCALE
OUTPUT VOLTAGE, OFFSET AND
SENSITIVITY RATIOMETRIC TO THE
SUPPLY VOLTAGE
FACTORY TRIMMED DEVICE SENSITIVITY
AND OFFSET
EMBEDDED SELF TEST
HIGH SHOCK SURVIVABILITY
DESCRIPTION
The LIS2L02AQ is a dual-axis 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 to detect the acceleration, is manufactured using a dedicated process
called THELMA (Thick Epi-Poly Layer for Microactuators and Accelerometers) developed by ST to produce inertial sensors and actuators in silicon.
QFN-44
Table 1. Order Codes
Part Number
Package
LIS2L02AQ
QFN-44
2g, 6g and it is capable of measuring accelerations
over a maximum bandwidth of 4.0 KHz for both the X
and Y axis. The device bandwidth may be reduced by
using external capacitances. A self-test capability allows the user to check the functioning of the system.
The LIS2L02AQ is available in plastic SMD package
and it is specified over a temperature range extending from -40°C to +85°C.
The LIS2L02AQ belongs to a family of products suitable for a variety of applications:
– Motion activated functions in mobile terminals
The IC interface instead is manufactured using a
CMOS process that allows high level of integration to
design a dedicated circuit which is trimmed to better
match the sensing element characteristics.
The LIS2L02AQ has a user selectable full scale of
– Gaming and Virtual Reality input devices
– Virtual reality input devices
– Antitheft systems and Inertial Navigation
– Appliance Control and Robotics
Figure 2. Block Diagram
CHARGE
AMPLIFIER
S1X
S1Y
rot
MUX
Routx
Voutx
Routy
Vouty
S/H
DEMUX
S2Y
S2X
S/H
VOLTAGE & CURRENT
REFERENCE
November 2004
TRIMMING CIRCUIT
&
TEST INTERFACE
CLOCK
&
PHASE GENERATOR
Rev. 3
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LIS2L02AQ
Figure 3. Pin Description
N°
Pin
1 to 3
NC
4
GND
Function
Internally not connected
0V supply
5
Vdd
6
Vouty
Power supply
7
ST
8
Voutx
9-13
NC
Internally not connected
14
PD
Power Down (Logic 0: normal mode; Logic 1: Power-Down mode)
15
NC
Internally not connected
16
FS
Full Scale selection (Logic 0: 2g Full-scale; Logic 1: 6g Full-scale)
17-18
Reserved
19
NC
20
Reserved
21
NC
22-23
Reserved
24-25
NC
Internally not connected
26
Reserved
Connect to Vdd or GND
27
Reserved
Leave unconnected or connect to Vdd
28
Reserved
Leave unconnected or connect to GND
29-44
NC
Output Voltage
Self Test (Logic 0: normal mode; Logic 1: Self-test)
Output Voltage
Leave unconnected
Internally not connected
Leave unconnected
Internally not connected
Leave unconnected
Internally not connected
1
Y
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
Figure 4. Pin Connection (Top view)
NC
NC
NC
NC
NC
NC
GND
NC
Vdd
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Reserved
ST
Reserved
Voutx
Reserved
Reserved
NC
Reserved
Reserved
Reserved
Reserved
Reserved
FS
NC
NC
NC
NC
NC
PD
NC
NC
DIRECTION OF THE
DETECTABLE
ACCELERATIONS
NC
LIS2L02AQ
Vouty
NC
X
LIS2L02AQ
Table 2. Electrical Characteristics
(Temperature range -40°C to +85°C) All the parameters are specified @ Vdd =3.3V, T=25°C unless
otherwise noted
Symbol
Parameter
Test Condition
Min.
Max.
Unit
Vdd
Supply voltage
3.3
5.25
V
Idd
Supply current
mean value
PD pin connected
to GND
0.85
1.5
mA
Supply current in Power Down
Mode
rms value
PD pin connected
to Vdd
2
5
µA
Zero-g level2
T = 25°C
Vdd/2
Vdd/2+10%
V
Zero-g level Vs temperature
Delta from +25°C
Acceleration range3
FS pin connected
to GND
FS pin connected
to Vdd
IddPdn
Voff
OffDr
Ar
So
SoDr
NL
2.4
Typ.1
Vdd/2-10%
±1.5
mg/°C
±1.8
±2.0
g
±5.4
±6.0
g
Sensitivity2
Full-scale = 2g
Vdd/5–10%
Vdd/5
Vdd/5+10%
Full-scale = 6g
Vdd/15–10%
Vdd/15
Vdd/15+10%
Sensitivity drift Vs
temperature
Delta from +25°C
±0.01
Non Linearity4
Best fit straight line
Full-scale = 2g
X, Y axis
±0.3
±1.5
% FS
±2
±4
%
4.0
4.8
KHz
CrossAx Cross-Axis5
fuc
Sensing Element Resonant
Frequency6
X, Y axis
an
Acceleration noise density
Vdd=3.3V;
Full-scale = 2g
Vt
Vst
Rout
Self test output voltage delta
change7,8,9
Self test input
Output impedance
3.2
V/g
V/g
%/°C
µg/
50
Hz
T = 25°C
Vdd=3.3V
Full-scale = 2g
X axis
-20
40
mV
T = 25°C
Vdd=3.3V
Full-scale = 2g
Y axis
20
-40
mV
Logic 0 level
0
0.8
V
Logic 1 level
2.2
Vdd
V
140
kΩ
80
110
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LIS2L02AQ
Table 2. Electrical Characteristics (continued)
(Temperature range -40°C to +85°C) All the parameters are specified @ Vdd =3.3V, T=25°C unless
otherwise noted
Symbol
Cload
Ton
Parameter
Capacitive load
Test Condition
Typ.1
Max.
320
drive10
Turn-On Time at exit from
Power Down mode
Min.
Cload in µF
Unit
pF
550*Cload
+0.3
ms
Notes: 1. Typical specifications are not guaranteed
2. Offset and sensitivity are essentially ratiometric to supply voltage
3. Guaranteed by wafer level test and measurement of initial offset and sensitivity
4. Guaranteed by design through measurements done up to 1g
5. Contribution to the measuring output of the inclination/acceleration along the perpendicular axis
6. Guaranteed by design
7. Self test “output voltage delta change” is defined as Vout(Vst=Logic1)-Vout(Vst=Logic0)
8. Self test “output voltage delta change” varies cubically with supply voltage
9. When full-scale is set to 6g, self-test “output delta change” is one third of the specified value
10.Bandwidth=1/(2*π*110KΩ*Cload)
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 3. Absolute Maximum Rating
Symbol
Ratings
Maximum Value
Unit
Vdd
Supply voltage
-0.3 to 7
V
Vin
Input voltage on any control pin (FS, PD, ST)
-0.3 to Vdd +0.3
V
APOW
Acceleration (Any axis, Powered, Vdd=3.3V)
3000g for 0.5 ms
10000g for 0.1 ms
AUNP
Acceleration (Any axis, Unpowered)
3000g for 0.5 ms
10000g for 0.1 ms
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TOP
Operating Temperature Range
-40 to +85
°C
TSTG
Storage Temperature Range
-40 to +105
°C
ESD
Electrostatic discharge protection
2KV HBM
LIS2L02AQ
3
FUNCTIONALITY
The LIS2L02AQ is a low-cost, low-power, analog output dual-axis linear accelerometer packaged in 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
The THELMA process is utilized 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
free to move on a plane parallel to the substrate itself. 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 molding
phase.
The equivalent circuit for the sensing element is shown in the figure below; when a linear acceleration is applied,
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.
Figure 5. Equivalent electrical circuit
Cps1
Rs1
S1x
Cs1y
Cpr
Rr
Cs2y
S2x
Cps2
Rs2
Cps1
Rs1
rot
S1y
Cs1z
Cpr
Rr
Cs2z
S2y
Cps2
Rs2
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LIS2L02AQ
The nominal value of the capacitors, at steady state, is few pF and when an acceleration is applied the maximum
variation of the capacitive load is few hundredths of pF.
3.2 IC Interface
The complete signal processing uses a fully differential structure, while the final stage converts the differential
signal into a single-ended one to be compatible with the external world.
The first stage is a low-noise capacitive amplifier that implements a Correlated Double Sampling (CDS) at its
output to cancel the offset and the 1/f noise. The produced signal is then sent to two different S&Hs, one for
each channel, and made available to the outside.
The low noise input amplifier operates at 200 kHz while the two 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 (output offset voltage and sensitivity) are ratiometric to the voltage supply. Increasing
or decreasing the voltage supply, the sensitivity and the offset will increase or decrease linearly. The feature
provides the cancellation of the error related to the voltage supply along an analog to digital conversion chain.
3.3 Factory calibration
The IC interface is factory calibrated to provide to the final user a device ready to operate.
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 thus
allowing the final user to utilize the device without any need for further calibration.
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LIS2L02AQ
4
PACKAGE INFORMATION
Figure 6. QFN-44 Mechanical Data & Package Dimensions
mm
inch
OUTLINE AND
MECHANICAL DATA
DIM.
MIN.
TYP.
MAX.
MIN.
TYP.
MAX.
A
1.70
1.80
1.90
0.067
0.071
0.075
A1
0.19
0.21
0.007
b
0.20
0.30
0.008
0.01
D
7.0
0.276
E
7.0
0.276
e
0.50
0.020
0.012
J
5.04
5.24
0.198
0.206
K
5.04
5.24
0.198
0.206
L
0.38
0.58
0.015
P
0.48
45 REF
0.019
0.023
QFN-44 (7x7x1.8mm)
Quad Flat Package No lead
45 REF
SEATING PLANE
0.25
0.008
M
G
M
N
34
44
44
1
33
1
DETAIL "N"
23
11
22
12
DETAIL G
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LIS2L02AQ
Table 4. Revision History
8/9
Date
Revision
January 2004
1
First Issue
Description of Changes
February 2004
2
Values of some parameters have been changed in Electrical
characteristics table.
November 2004
3
Changed the maturity from Product Preview to Final.
Modified/added some values in the table 2 Electrical characteristics.
LIS2L02AQ
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.
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All other names are the property of their respective owners
© 2004 STMicroelectronics - All rights reserved
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