STMICROELECTRONICS LIS2L01

LIS2L01
INERTIAL SENSOR:
2Axis/1g LINEAR ACCELEROMETER
PRODUCT PREVIEW
■
THE SENSITIVITY IS ADJUSTED WITH A
TOTAL ACCURACY OF ±2.5%
INTERNAL TWO POLES LOW PASS SC
FILTER WITH LINEAR OUTPUT, 30Hz
BANDWIDTH
THE OUTPUT VOLTAGE, OFFSET,
SENSITIVITY AND TEST VOLTAGE ARE
RATIOMETRIC TO THE SUPPLY VOLTAGE
DEVICE SENSITIVITY IS ON-CHIP FACTORY
TRIMMED
EMBEDDED SELF TEST
■
HIGH SHOCK SURVIVABILITY
■
■
■
■
SO-24
ORDERING NUMBER: LIS2L01
The LIS2L01 is capable of measuring acceleration in
the range of ±1g with a bandwidth of 30Hz, set by a
2nd order low pass filter. A self-test capability verifies
the system providing to the user a signal on a dedicated pin.
DESCRIPTION
The LIS2L01 is a dual channel accelerometer that includes a sensor elements and an IC interface able to
take the information from the sensor and to provide
an analog signal to the external world.
The LIS2L01 is available in plastic SMD package and
it is specified over a temperature range from 0°C to
+80°C.
The LIS2L01 is a part of family products suitable for
a variety of applications:
– Virtual reality input devices
The sensor 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 sensor and actuator in silicon.
– Computer hard disk drive protection
– Computer mouse and joysticks
The IC interface instead is manufactured using a
CMOS process that allow high level of integration to
design a dedicated circuit which is trimmed to better
match the sensor element characteristics.
– Vibration Monitoring, recording and compensation
– Appliance control
– Robotics
BLOCK DIAGRAM
Sy
CHARGE
PREAMPLIFIER
Sx
MUX
Sy
SC
FILTER
&
CDS
MUX
SC
FILTER
&
CDS
Sx
TRIMMING CIRCUIT
& POLY FUSES
VOLTAGE &
CURRENT
REFERENCE
VARIABLE GAIN
AMPLIFIER
VOUTx
VARIABLE GAIN
AMPLIFIER
VOUTy
CLOCK &
PHASE
GENERATOR
D01IN1315
April 2002
This is preliminary information on a new product now in development. Details are subject to change without notice.
1/6
LIS2L01
PIN DESCRIPTION
N°
Pin
Function
1 to 5
NC
6, 9, 10
Reserved
Leave unconnected or connect to GND
7, 8
Reserved
Leave unconnected or connect to Vdd
11, 12
NC
Internally not connected
13
Vdd
5V Supply
14
GND
0V Supply
15
VoutX
Voltage Output
16
ST
17
VoutY
18
Reserved
Leave unconnected or connect to GND
19
Reserved
Leave unconnected or connect to Vdd
20 to 24
NC
Internally not connected
Self Test
Voltage Output
Internally not connected
PIN CONNECTION (Top view)
N.C.
1
24
N.C.
N.C.
2
23
N.C.
N.C.
3
22
N.C.
N.C.
4
21
N.C.
N.C.
5
20
N.C.
DIRECTION OF THE RESERVED
DETECTABLE
RESERVED
ACCELERATION
RESERVED
6
19
RESERVED
7
18
RESERVED
8
17
VoutY
RESERVED
9
16
ST
RESERVED
10
15
VoutX
N.C.
11
14
GND
N.C.
12
13
Vdd
Y
X
D01IN1314
2/6
LIS2L01
ELECTRICAL CHARACTERISTCS (Temperature range 0°C to 80°C, supply voltage Vdd = 5V ±5%.)
Symbol
1
Parameter
Vdd
Supply voltage
Idd
Supply current
Voff
Zero-g level
Test Condition
Min.
Typ.
Max.
Unit
4.75
5
5.25
V
10
T = 25°C
ratiometric to Vdd
mA
Vdd/2
– 0.1
Vdd/2
Vdd/2
+ 0.1
V
TBD
±1
TBD
g
Ar
Acceleration range
So
Sensitivity ratiometric to Vdd
Vdd = 5V
T = 25°C
1.8
2
2.2
V/g
fuc
Upper cutoff frequency low pass
filter
-3dB/2nd order filter
27
30
33
Hz
an
Equivalent noise acceleration
Bandwidth = 0.1…30Hz
Vt
Self test output voltage
Ratiometric to Vdd
T = 25°C
@ 5V
Vst
Self test input
Logic 1 voltage
Logic 0 voltage
Cload
Capacitive load drive
Rload
Resistive load output
1
mg
TBD
V
3.75
Vss
50
Vdd
1.25
V
V
100
pF
kΩ
FUNCTIONALITY
1.1 Sensor element
The ThELMA process is utilized to create a surface micro-machined accelerometer. The technology allows carry out silicon structure on suspension, the structure are attached to the substrate in few points called anchor
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 the sensor element to avoid the molding goes between the elements making the
sensor useless.
The equivalent circuit for the sensor is shown in the below figure; 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.
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 tenth of pF.
3/6
LIS2L01
Figure 1. Equivalent electrical circuit
Cps1
Rs1
S1x
Cs1x
Cpr
Rr
Cs2x
S2x
Cps2
Rs2
Cps1
Rs1
rot
S1y
Cs1y
Cpr
Rr
Cs2y
S2y
Cps2
Rs2
1.2 IC Interface
The complete signal processing uses a fully differential structure, while the final stage converts the differential
signal into a single-ended to be compatible with the external world.
The first stage is a low-noise capacitive amplifier that implements a Correlated Double Sampling (CDS) at the
output to cancel the offset and the 1/f noise.
The signal is processed through a 2nd order low pass filter in order to reject out of band noise, the filter cut off
frequency is set to be 30Hz.
This filter is implemented using SC technique, which allows to realize a fully integrated system that avoid the
use of any external component.
The low noise input amplifier operates at 100 kHz while the two SC filters operate at 50 kHz sampling frequency.
This allows a large oversampling ratio, able to reduce in-band noise and to obtain an accurate output waveform.
The signal at the output of the SC filter is sampled and held using a different clock to avoid that the filter output
value during the CDS phase reaches the output pin.
All the analog parameter (output offset voltage and sensitivity) are ratiometric to the supply voltage. Increasing
or decreasing the supply voltage, the sensitivity and the offset will increase or decrease linearly. The feature
provides the cancellation of the error related to the supply voltage in the analog to digital conversion chain.
1.3 Factory calibration
In the IC interface different calibrations take place at factory level to provide to final user a device ready to be
used, the trimmed parameters are: gain, offset and cut off frequency of the SC filter.
The trimmed value are stored in the device with a poly-fuse technique. Any time the device is turned on the
memorized bits are loaded into the registers to be utilized during the normal operation. The poly-fuse approach
allow the final user to use the device without any need for further calibration.
4/6
LIS2L01
mm
DIM.
MIN.
TYP.
inch
MAX.
MIN.
TYP.
MAX.
A
2.35
2.65
0.093
0.104
A1
0.10
0.30
0.004
0.012
A2
2.55
0.100
B
0.33
0.51
0.013
0.0200
C
0.23
0.32
0.009
0.013
D
15.20
15.60
0.598
0.614
E
7.40
7.60
0.291
0.299
e
1.27
0,050
H
10.0
10.65
0.394
0.419
h
0.25
0.75
0.010
0.030
k
OUTLINE AND
MECHANICAL DATA
0˚ (min.), 8˚ (max.)
SO24
L
0.40
1.27
0.016
0.050
0.10mm
B
e
A
A2
h x 45˚
A1
K
A1
L
.004
C
H
Seating Plane
D
13
1
12
E
24
SO24
5/6
LIS2L01
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
 2002 STMicroelectronics - All Rights Reserved
STMicroelectronics GROUP OF COMPANIES
Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan -Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - United States.
http://www.st.com
6/6