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LIS244ALH
MEMS inertial sensor
high performance 2-axis ±2/±6g ultracompact linear accelerometer
Features
■ 2.4 V to 3.6 V single supply operation
■ ±2 g / ±6 g user selectable full-scale
■ Low power consumption
■ Output voltage, offset and sensitivity are
ratiometric to the supply voltage
■ Factory trimmed device sensitivity and offset
■ Embedded self test
■ RoHS/ECOPACK
■ High shock survivability ( 10000 g )
®
compliant
Description
The LIS244ALH is an ultra compact consumer
low-power two-axis linear accelerometer that
includes a sensing element and an IC interface
able to take the information from the sensing
element and 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 an ST
proprietary CMOS process with high level of
integration. The dedicated circuit is trimmed to
better match the sensing element characteristics.
LGA16
The LIS244ALH has a dynamically user
selectable full-scale of ±2 g / ±6 g and it is
capable of measuring accelerations over a
maximum bandwidth of 2.0 kHz for all axes. The
device bandwidth may be reduced by using
external capacitances. The self-test capability
allows the user to check the functioning of the
system.
The LIS244ALH is available in Land Grid Array
package (LGA) manufactured by ST.
It is guaranteed to operate over an extended
temperature range of -40 °C to +85 °C.
The LIS244ALH belongs to a family of products
suitable for a variety of applications:
– Mobile terminals
– Gaming and virtual reality input devices
– Antitheft systems and inertial navigation
– Appliance and robotics.
(4x4x1.5mm)
Table 1. Device summary
Order code Temp range [° C] Package Packing
LIS244ALH -40 to +85 LGA-16 Tray
LIS244ALHTR -40 to +85 LGA-16 Tape and reel
February 2008 Rev 2 1/16
www.st.com
16
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Content LIS244ALH
Content
1 Block diagram and pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Mechanical and electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Mechanical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.4 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3 Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1 Sensing element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2 IC interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3 Factory calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4 Application hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1 Soldering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2 Output response vs. orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2/16
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LIS244ALH List of figures
List of figures
Figure 1. Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 2. Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3. LIS244ALH electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 4. Output response vs. orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Figure 5. LGA16: mechanical data and package dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3/16
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List of tables LIS244ALH
List of tables
Table 1. Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Table 2. Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Table 3. Mechanical characteristics @ Vdd =3.3 V, T = 25 °C unless otherwise noted. . . . . . . . . . . 7
Table 4. Electrical characteristics @ Vdd =3.3 V, T = 25 °C unless otherwise noted. . . . . . . . . . . . . 8
Table 5. Absolute maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Table 6. Filter capacitor selection, C
Table 7. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
(x,y) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
load
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Page 5
LIS244ALH Block diagram and pin description
1 Block diagram and pin description
1.1 Block diagram
Figure 1. Block diagram
X+
Y+
a
Y-
X-
SELF TEST
1.2 Pin description
Figure 2. Pin connection
MUX
REFERENCE
CHARGE
AMPLIFIER
DEMUX
TRIMMING CIRCUIT
S/H
S/H
Routx
Routy
CLOCK
VoutX
VoutY
1
X
(TOP VIEW)
DIRECTIONS OF THE
DETECTABLE
ACCELERATIONS
Vdd
NC
13 16
VoutX
12
NC
VoutY
Y
NC
8
NC
Res
NC
5
GNDNCPD
1
FS
ST
NC
49
Res
(BOTTOM VIEW)
5/16
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Block diagram and pin description LIS244ALH
Table 2. Pin description
Pin # Pin name Function
1 FS Full scale selection (Logic 0: ±2g Full-scale; Logic 1: ±6g Full-scale)
2 ST Self test (Logic 0: normal mode; Logic 1: Self-test mode)
3 NC Internally not connected
4 Res Leave Unconnected or Connect to Vdd
5 PD Power Down (Logic 0: normal mode; Logic 1: Power-Down mode)
6 NC Internally not connected
7 GND 0V supply
8 NC Internally not connected
9 NC Internally not connected
10 VoutY Output voltage Y channel
11 NC Internally not connected
12 VoutX Output voltage X channel
13 NC Internally not connected
14 Vdd Power supply
15 Res Connect to Vdd
16 NC Internally not connected
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LIS244ALH Mechanical and electrical specifications
2 Mechanical and electrical specifications
2.1 Mechanical characteristics
Table 3. Mechanical characteristics @ Vdd =3.3 V, T = 25 °C unless otherwise noted
± 2
(2)
Max. Unit
Symbol Parameter Test condition Min. Typ.
FS pin connected to
(3)
Ar Acceleration range
GND
(1)
FS pin connected to Vdd ± 6
Full-scale = ±2 g Vdd/5 - 5% Vdd/5 Vdd/5 + 5%
So Sensitivity
SoDr
Sensitivity change vs
temperature
Voff Zero-g level
OffDr
Zero-g level change vs
temperature
NL Non linearity
CrossAx Cross-axis
Acceleration noise
An
density
Self test output voltage
Vt
change
Fres
Top
Sensing element
resonant frequency
Operating temperature
range
(4)
(4)
(5)
(6)
(7),(8),(9)
Full-scale = ±6 g Vdd/15 - 10% Vdd/15
Vdd/15 +
10%
Delta from +25 °C ± 0.01 %/°C
Full-scale = ±2 g
T = 25 °C
Vdd/2 - 4% Vdd/2 Vdd/2 + 4% V
Delta from +25 °C ±0.4 mg/°C
Best fit straight line
Full-scale = ±2 g
±0.5 % FS
±2 %
Vdd = 3.3 V;
Full-scale = ±2 g
X axis
T = 25 °C; Vdd=3.3 V
Y axis
T = 25 °C; Vdd=3.3 V
X,Y axis 2.0 KHz
(10)
50 µg/
140 mV
-140 mV
-40 +85 °C
Wh Product weight 0.040 gram
1. The product is factory calibrated at 3.3 V. The operational power supply range is from 2.4 V to 3.6 V. Voff, So and Vt
parameters will vary with supply voltage.
2. Typical specifications are not guaranteed.
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 at the calibration level ±8%.
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
8. “Self test output voltage change” varies cubically with supply voltage.
9. When Full-scale is set to ±6 g, “Self test output voltage change” is one third of the specified value at ±2 g.
10. Minimum resonance frequency Fres=2.0 KHz. Sensor bandwidth=1/(2*π*110kΩ*Cload), with Cload>1 nF.
(Vst=Logic1)
-Vout
(Vst=Logic0)
.
g
V/g
Hz
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Mechanical and electrical specifications LIS244ALH
2.2 Electrical characteristics
Table 4. Electrical characteristics @ Vdd =3.3 V, T = 25 °C unless otherwise noted
Symbol Parameter Test condition Min. Typ.
(2)
(1)
Max. Unit
Vdd Supply voltage 2.4 3.3 3.6 V
Normal mode 680
Idd Supply current
Power-down mode 1 5
Vfs
Vst
Vpd
Rout
Cload
To n
To p
1. The product is factory calibrated at 3.3 V.
2. Typical specifications are not guaranteed.
3. Minimum resonance frequency Fres=2.0 KHz. Device bandwidth=1/(2*π*110 kΩ*Cload), with Cload>1 nF.
Full-scale input
Self-test input
Power-down input
Output impedance of
VoutX, VoutY
Capacitive load drive
(3)
for VoutX, VoutY
Turn-on time at exit of
Power-down mode
Operating temperature
range
Logic 0 level 0 0.3*Vdd V
Logic 1 level 0.7*Vdd Vdd V
90 110 130 KΩ
1nF
Cload expressed in µF
550*Cload+
0.3
-40 +85 ºC
µA
ms
8/16
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LIS244ALH 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 5. Absolute maximum rating
Symbol Ratings Maximum value Unit
Vdd Supply voltage -0.3 to 6 V
Vin Input voltage on any control pin (FS, ST, PD) -0.3 to Vdd +0.3 V
A
Acceleration (any axis, powered, Vdd = 3.3 V)
POW
3000 g for 0.5 ms
10000 g for 0.1 ms
A
T
ESD Electrostatic discharge protection
Acceleration (any axis, not powered)
UNP
Storage temperature range -40 to +125 °C
STG
3000 g for 0.5 ms
10000 g for 0.1 ms
4 (HBM) KV
1.5 (CDM) KV
400 (MM) 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
9/16
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Mechanical and electrical specifications LIS244ALH
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 = 1650 mV. A deviation from ideal 0-g
level (1650 mV 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.
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 Ta bl e 3 , then the sensor is working properly and the
parameters of the interface chip are within the defined specification.
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 1 nF 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 close to the resonance frequency of
the sensor. In general the smallest possible bandwidth for a particular application should be
chosen to get the best results.
10/16
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LIS244ALH Functionality
3 Functionality
The LIS244ALH is an ultra compact low-power, analog output two-axis linear accelerometer
packaged in a LGA package. The complete device includes a sensing element and an IC
interface able to take the information from the sensing element and 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 in the fF range.
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.
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. This 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 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.
11/16
Page 12
Application hints LIS244ALH
4 Application hints
Figure 3. LIS244ALH electrical connection
Vdd
µ
F
Optional
Optional
Vout x
Vout y
1
X
(TOP VIEW)
DIRECTIONS OF THE
DETECTABLE
ACCELERATIONS
µF Aluminum)
FS
ST
16
15 14 13
1
2
LIS244ALH
(top view)
3
4
5
67
PD
GND
Digital signals
GND
100nF
8
12
11
10
9
GND
10
Cload X
Cload Y
Power supply decoupling capacitors (100 nF ceramic or polyester + 10
should be placed as near as possible to the device (common design practice).
Pin 1 indicator
Y
The LIS244ALH allows to band limit VoutX and VoutY through the use of external
capacitors. The recommended frequency range spans from DC up to 2.0 KHz. In particular,
capacitors are added at output VoutX and VoutY pins to implement low-pass filtering for
antialiasing and noise reduction. The equation for the cut-off frequency (f
filters is in this case:
f
---------------------------------------------------------------- -=
t
2π R
Taking into account that the internal filtering resistor (R
110 KΩ, the equation for the external filter cut-off frequency may be simplified as follows:
f
t
The tolerance of the internal resistor can vary typically of
110 KΩ; thus the cut-off frequency will vary accordingly. A minimum capacitance of 1 nF for
C
(x, y) is required.
load
12/16
1
outCload
1.45µF
------------------------------ -
C
load
xy,()
) of the external
t
xy,()⋅⋅
) has a nominal value equal to
out
Hz[]=
±20% within its nominal value of
Page 13
LIS244ALH Application hints
Table 6. Filter capacitor selection, C
Cut-off frequency Capacitor value
1 Hz 1500 nF
10 Hz 150 nF
20 Hz 68 nF
50 Hz 30 nF
100 Hz 15 nF
200 Hz 6.8 nF
500 Hz 3 nF
4.1 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/mems
load
(x,y)
.
4.2 Output response vs. orientation
Figure 4. Output response vs. orientation
X=2.31V (+1g)
Y=1.65V (0g)
X=1.65V (0g)
Y=0.99V (-1g)
Figure 4 shows output voltage values of LIS244ALH, powered at 3.3 V, with full-scale ±2 g.
X=1.65V (0g)
Y=2.31V (+1g)
X=0.99V (-1g)
Y=1.65V (0g)
Bottom
To p
To p
Bottom
X=1.65V (0g)
Y=1.65V (0g)
X=1.65V (0g)
Y=1.65V (0g)
Earth’s Surface
13/16
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Package information LIS244ALH
5 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
ECOPACK
®
specifications are available at: www.st.com.
Figure 5. LGA16: mechanical data and package dimensions
Dimensions
Ref.
A1 1.500 1.600 0.05910.0630
A2 1.330 0.0524
A3 0.160 0.200 0.240 0.0063 0.0079 0.0094
d0.300 0.0118
D1 3.850 4.000 4.150 0.1516 0.1575 0.1634
E1 3.850 4.000 4.150 0.1516 0.1575 0.1634
L2 1.950 0.0768
M 0.100 0.0039
N1 0.650 0.0256
N2 0.98 00.0386
P1 1.750 0.0689
P2 1.525 0.0600
T1 0.400 0.0157
T2 0.300 0.0118
k 0.050 0.0020
mm inch
Min. Typ. Max. Min. Typ. Max.
LGA16L (4x4x1.5mm)
Land Grid Array Package
®
is an ST trademark.
Outline and
mechanical data
14/16
7974136D
Page 15
LIS244ALH Revision history
6 Revision history
Table 7. Document revision history
Date Revision Changes
15-Jan-2008 1 Initial release.
19-Feb-2008 2 Updated Figure 2: Pin connection on page 5
15/16
Page 16
LIS244ALH
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