Page 1
LIS332AX
MEMS inertial sensor:
3-axis ±2 g absolute analog-output ultracompact accelerometer
Features
■ Single voltage supply operation
■ ±2 g full-scale
■ Excellent stability over temperature
■ Absolute 0-g level and sensitivity
■ Factory-trimmed device sensitivity and
0-g level
■ Power-down mode
■ Embedded self-test
■ 10000 g high shock survivability
■ ECOPACK® RoHS and “Green” compliant
(see Section 7)
Applications
■ Tilting applications
■ Free-fall detection
■ Gaming
■ Anti-theft systems
■ Inertial navigation and motion tracking
LGA-16
The IC interface is manufactured using a CMOS
process that allows a high level of integration to
design a dedicated circuit trimmed to better match
the sensing element characteristics.
The LIS332AX has a full-scale of
capable of measuring accelerations over a
maximum bandwidth of 2.0 kHz. The device
bandwidth may be reduced by using external
capacitors. The self-test capability allows the user
to check the functioning of the system.
ST is already in the field with several hundred
million sensors which have received excellent
acceptance from the market in terms of quality,
reliability and performance.
(3x3x1.0mm)
±2 g, and is
Description
The LIS332AX is an ultracompact low-power 3axis linear accelerometer that includes a sensing
element and an IC interface to provide an analog
signal to the external world.
The sensing element, capable of detecting the
The LIS332AX is provided in a plastic land grid
array (LGA) package.
Several years ago ST successfully pioneered the
use of this package for accelerometers. Today, ST
has the widest manufacturing capability and
strongest expertise in the world for production of
sensors in plastic LGA packages.
acceleration, is manufactured using a dedicated
process developed by ST to produce inertial
sensors and actuators in silicon.
Table 1. Device summary
February 2010 Doc ID 16932 Rev 1 1/14
Part number Temperature range, ° C Package Packing
LIS332AX -40°C to +85°C LGA-16 Tray
LIS332AXTR -40°C to +85°C LGA-16 Tape and reel
www.st.com
14
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Contents LIS332AX
Contents
1 Block diagram and pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Pin connections and description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Mechanical and electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Mechanical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1 Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2 Zero-g level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3 Self-test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.4 Output impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5 Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1 Sensing element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.2 IC interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.3 Factory calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6 Application hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1 Soldering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.2 Output response vs. orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2/14 Doc ID 16932 Rev 1
Page 3
LIS332AX Block diagram and pin description
1 Block diagram and pin description
Figure 1. Block diagram
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1.1 Pin connections and description
Figure 2. Pin connection
3(
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2OUTX
2OUTY
2OUTZ
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Doc ID 16932 Rev 1 3/14
Page 4
Block diagram and pin description LIS332AX
Table 2. Pin description
Pin # Pin name Function
1 NC Internally not connected
2 res Connect to Vdd
3 NC Not connected
4 ST Self-test (logic 0: normal mode; logic 1: self-test mode)
5 PD Power-down (logic 0: normal mode; logic 1: power-down mode)
6 GND 0 V supply
7 NC Not connected
8 NC Not connected
9 Voutz Output voltage Z channel
10 NC Not connected
11 Vouty Output voltage Y channel
12 NC Not connected
13 Voutx Output voltage X channel
14 NC Not connected
15 res Connect to Vdd
16 Vdd Power supply
4/14 Doc ID 16932 Rev 1
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LIS332AX Mechanical and electrical specifications
2 Mechanical and electrical specifications
2.1 Mechanical characteristics
@ Vdd=3 V, T=25 °C unless otherwise noted
Table 3. Mechanical characteristics
Symbol Parameter Test condition Min. Typ.
(4)
(4)
(6)
(2)
Delta from +25 °C ±0.01 %/°C
T = 25°C 1.25-3.5% 1.25 1.25+3.5% V
Delta from +25 °C ±0.2 mg/°C
Best fit straight line ±0.5 % FS
Vdd=3 V 100 µg/
T = 25 °C
X axis
T = 25 °C
Y axis
T = 25 °C
Z axis
X, Y, Z axis 2.0 kHz
(7)
(Vst=Logic1)
=2.0 kHz. Sensor bandwidth=1/(2*π*32kΩ*C
RES
Ar Acceleration range
So Sensitivity
SoDr
Sensitivity change vs.
temperature
(3)
Voff Zer o-g level
OffDr
Zero-g level change
vs. temperature
NL Non linearity
CrossAx Cross-axis
Acceleration noise
An
density
Self-test output
Vt
voltage change
Fres
Top
Sensing element
resonant frequency
Operating
temperature range
(5)
Wh Product weight 30 mgram
1. Typical specifications are not guaranteed
2. Guaranteed by wafer level test and measurement of initial offset and sensitivity
3. Zero-g level and Sensitivity are absolute to supply voltage
4. Guaranteed by design
5. Contribution to the measuring output of an inclination/acceleration along any perpendicular axis
6. “Self-test output voltage change” is defined as Vout
7. Minimum resonance frequency F
(a)
(1)
Max. Unit
±2.0 g
0.363 - 5% 0.363 0.363 + 5% V/g
±2 %
40 550 mV
40 550 mV
40 550 mV
-40 +85 °C
-Vout
(Vst=Logic0)
LOAD
), with C
LOAD
>2.5 nF
Hz
a. The product is factory calibrated at 3 V. The operational power supply range is specified in Table 4.
Doc ID 16932 Rev 1 5/14
Page 6
Mechanical and electrical specifications LIS332AX
2.2 Electrical characteristics
@ Vdd=3 V, T=25 °C unless otherwise noted
Table 4. Electrical characteristics
Symbol Parameter Test condition Min. Typ.
Vdd Supply voltage 2.16 3 3.6 V
Idd Supply current
Mean value
PD pin connected to GND
(b)
.
(1)
300 µA
Max. Unit
IddPdn
Vst
Vpd
Rout
Supply current in
power-down mode
Self-test input
Power-down input
Output impedance of
Voutx, Vo uty, Vou tz
PD pin connected to Vdd 1 µA
Logic 0 level 0 0.2*Vdd
Logic 1 level 0.8*Vdd Vdd
32 kΩ
Capacitive load drive
Cload
fo r Vou tx, Vouty,
(2)
Voutz
2.5 nF
Turn-on time
To n
at exit from
C
in µF 160*C
LOAD
+0.3 ms
LOAD
Power-down mode
1. Typical specifications are not guaranteed
2. Minimum resonance frequency Fres=2.0kHz. Device bandwidth=1/(2*π*32kΩ*Cload), with Cload>2.5nF
V
b. The product is factory calibrated at 3 V. The operational power supply range is specified in Table 4.
6/14 Doc ID 16932 Rev 1
Page 7
LIS332AX Absolute maximum ratings
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 5. Absolute maximum ratings
Symbol Ratings Maximum value Unit
Vdd Supply voltage -0.3 to 6 V
Vin Input voltage on any control pin (PD, ST) -0.3 to Vdd +0.3 V
A
A
T
Acceleration (any axis, powered, Vdd=3V)
POW
Acceleration (any axis, not powered)
UNP
Storage temperature range -40 to +125 °C
STG
ESD Electrostatic discharge protection
Note: Supply voltage on any pin should never exceed 6.0 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
3000 g for 0.5 ms
10000 g for 0.1 ms
3000 g for 0.5 ms
10000 g for 0.1 ms
4 (HBM) kV
1.5 (CDM) kV
200 (MM) V
Doc ID 16932 Rev 1 7/14
Page 8
Terminology LIS332AX
4 Terminology
4.1 Sensitivity
Sensitivity describes the gain of the sensor and can be determined by applying 1 g
acceleration to it. Because the sensor can measure DC accelerations, this can be done
easily by pointing the selected axis towards the ground, noting the output value, rotating the
sensor 180 degrees (pointing towards the sky) and noting the output value again. By doing
so, a ±1 g acceleration is applied to the sensor. Subtracting the larger output value from the
smaller one, and dividing the result by 2, produces the actual sensitivity of the sensor. This
value changes very little over temperature (see sensitivity change vs. temperature) and over
time. The sensitivity tolerance describes the range of sensitivities of a large number of
sensors.
4.2 Zero-g level
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 0 g on both the X and Y axes,
whereas the Z axis will measure 1 g. A deviation from the ideal 0-g level (1250 mV, in this
case) is called Zero-g offset. Offset is to some extent a result of stress to the MEMS 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” in Table 3: Mechanical characteristics). The
Zero-g level of an individual sensor is also very stable over its lifetime. The Zero-g level
tolerance describes the range of Zero-g levels of a group of sensors.
4.3 Self-test
Self-test (ST) provides a means of testing of the mechanical and electrical parts of the
sensor, allowing the seismic mass to be moved by through 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 exhibits a voltage change in its DC levels. 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 in Table 3, then the sensor is working properly and
the parameters of the interface chip are within the defined specifications.
4.4 Output impedance
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 2.5 nF and the internal
resistor. Due to the 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 close to the resonant frequency of the sensor. In
general, the smallest possible bandwidth for a particular application should be chosen to
obtain the best results.
8/14 Doc ID 16932 Rev 1
Page 9
LIS332AX Functionality
5 Functionality
The LIS332AX is a 3-axis ultracompact low-power, analog output linear accelerometer
packaged in an LGA package. The complete device includes a sensing element and an IC
interface capable of taking information from the sensing element providing an analog signal
to the external world.
5.1 Sensing element
A proprietary process is used to create a surface micro-machined accelerometer. The
technology allows the creation of suspended silicon structures which are attached to the
substrate at several points called “anchors” and are free to move in the direction of the
sensed acceleration. To be compatible with traditional packaging techniques, a cap is
placed on top of the sensing element to prevent blocking of the moving parts during the
moulding phase of plastic encapsulation.
When an acceleration is applied to the sensor, the proof mass shifts 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 a few pF, and when an acceleration
is applied the maximum variation of the capacitive load is in the fF range.
5.2 IC interface
The complete signal processing utilizes a fully differential structure, while the final stage
converts the differential signal into a single-ended signal to be compatible with external
applications.
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 signal produced is
then sent to three different S&Hs, one for each channel, and made available to the outside.
All the analog parameters (output offset voltage and sensitivity) are absolute with respect to
the voltage supply. Increasing or decreasing the voltage supply will not cause a change in
the sensitivity and the offset. The feature allows the coupling of the sensor with an ADC,
having a fixed voltage reference independent from Vdd.
5.3 Factory calibration
The IC interface is factory-calibrated for sensitivity (So) and Zero-g level (Voff). The trimming
values are stored in the device in a non-volatile structure. Any time the device is turned on,
the trimming parameters are downloaded to the registers to be employed during normal
operation. This allows the user to use the device without further calibration.
Doc ID 16932 Rev 1 9/14
Page 10
Application hints LIS332AX
6 Application hints
Figure 3. LIS332AX electrical connection
6DD
/PTIONAL
8
6OU T X
6OU T Y
6OUTZ
4OP VIEW
$IRECTION
OFTHE
DETECTABLE
ACCELERATION
0ININDICATOR
9
:
S
34
0$
,)3!8
TOPVIEW
'.$
'.$
N&
'.$
P
&
#LOADX
#LOADY
#LOADZ
$IGITALSIGNALS
!-V
Power supply decoupling capacitors (100 nF ceramic or polyester + 10 µF aluminum) should
be placed as near as possible to the device (common design practice).
The LIS332AX allows band limiting of Voutx, Vouty and Voutz through the use of external
capacitors. The recommended frequency range spans from DC up to 2.0 kHz. Capacitors
must be added at the output pins to implement low-pass filtering for anti-aliasing and noise
reduction. The equation for the cut-off frequency ( f
f
------------------------------------------------------------------------=
t
2π R
out
Taking into account that the internal filtering resistor (R
) of the external filters is:
t
1
C
load
xyz,,()⋅⋅
) has a nominal value of 32 kΩ, the
out
equation for the external filter cut-off frequency may be simplified as follows:
load
5µF
Hz[]=
xyz,,()
-------------------------------------- -
f
t
C
The tolerance of the internal resistor can vary ±20% (typ) from its nominal value of 32 kΩ;
thus the cut-off frequency will vary accordingly. A minimum capacitance of 2.5 nF for C
LOAD
(x, y, z) is required.
10/14 Doc ID 16932 Rev 1
Page 11
LIS332AX Application hints
Table 6. Filter capacitor selection, C
Cut-off frequency Capacitor value
1 Hz 5 µF
10 Hz 0.5 µF
20 Hz 250 nF
50 Hz 100 nF
100 Hz 50 nF
200 Hz 25 nF
500 Hz 10 nF
6.1 Soldering information
The LGA package is compliant with the ECOPACK®, RoHs and “Green” standard.
It is qualified for soldering heat resistance according to JEDEC J-STD-020C.
Leave “Pin 1 Indicator” unconnected during soldering.
Land pattern and soldering recommendations are available at www.st.com.
LOAD
(x,y,z)
6.2 Output response vs. orientation
Figure 4. Output response vs. orientation
X=1.25V (0g)
Y=1.61V (+1g)
Z=1.25V (0g)
X=1.61V (+1g)
Y=1.25V (0g)
Z=1.25V (0g)
TOP VIEW
X=1.25V (0g)
Y=0.89V (-1g)
Z=1.25V (0g)
X=0.89V (-1g)
Y=1.25V (0g)
Z=1.25V (0g)
Bottom
To p
To p
Bottom
Earth’ surface
X=1.25V (0g)
Y=1.25V (0g)
Z=1.61V (+1g)
X=1.25V (0g)
Y=1.25V (0g)
Z=0.89V (-1g)
Doc ID 16932 Rev 1 11/14
Page 12
Package information LIS332AX
7 Package information
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com. ECOPACK
is an ST trademark.
Figure 5. LGA-16: mechanical data and package dimensions
Dimensions
Ref.
A1 1.000 0.0394
A2 0.7850.0309
A3 0.200 0.0079
D1 2.850 3.000 3.150 0.1122 0.1181 0.1240
E1 2.850 3.000 3.150 0.1122 0.1181 0.1240
L1 1.000 1.060 0.0394 0.0417
L2 2.000 2.060 0.07870.0811
N1 0.500 0.0197
N2 1.000 0.0394
M 0.040 0.100 0.160 0.0016 0.0039 0.0063
P1 0.875 0.0344
P2 1.275 0.0502
T1 0.290 0.350 0.410 0.0114 0.0138 0.0161
T2 0.190 0.250 0.310 0.0075 0.0098 0.0122
d0.150 0.0059
k 0.050 0.0020
mm inch
Min. Typ. Max. Min. Typ. Max.
Land Grid Array Package
Outline and
mechanical data
LGA-16(3x3x1.0mm)
12/14 Doc ID 16932 Rev 1
DRAFT
7983231
Page 13
LIS332AX Revision history
8 Revision history
Table 7. Document revision history
Date Revision Changes
02-Feb-2010 1 Initial release
Doc ID 16932 Rev 1 13/14
Page 14
LIS332AX
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14/14 Doc ID 16932 Rev 1
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