E-LIS2L02AS4 - STMicroelectronics

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LIS2L02AS4

December 2005

1 Features

■2.4V TO 5.25V SINGLE SUPPLY OPERATION

■LOW POWER CONSUMPTION

■±2g/±6g USER SELECTABLE FULL-SCALE

■0.3mg 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

2 Description

The LIS2L02AS4 is a low-power two 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 ac-

celeration, is manufactured using a dedicated pro-

cess 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 LIS2L02AS4 has a user selectable full scale

of ±2g, ±6g and it is capable of measuring acceler-

ations over a bandwidth of 1.5kHz for all axes. The

device bandwidth may be reduced by using exter-

nal capacitances. A self-test capability allows to

check the mechanical and electrical signal path of

the sensor.

The LIS2L02AS4 is available in plastic SMD pack-

age and it is specified over an extended tempera-

ture range of -40°C to +85°C.

The LIS2L02AS4 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

MEMS INERTIAL SENSOR:

2-Axis - ±2g/±6g LINEAR ACCELEROMETER

Figure 2. Block Diagram

DEMUX

S/H

CHARGE

AMPLIFIER

S/H

MUX

Y+

Y-

Voutx

Vouty

Routx

Routy

TRIMMING CIRCUIT CLOCK

X+

X-

SELF TEST REFERENCE

gure 1.

age

Table 1. Order Codes

Part Number Package Finishing

E-LIS2L02AS4 SO24 Tube

E-LIS2L02AS4TR SO24 Tape & Reel

SO-24

Rev. 2

LIS2L02AS4

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Table 2. Pin Description

Figure 3. Pin Connection (Top view)

N° Pin Function

1 to 5 NC Internally not connected

6GND0V supply

7 Vdd Power supply

8 Vouty Output Voltage

9 ST Self Test (Logic 0: normal mode; Logic 1: Self-test)

10 Voutx Output Voltage

11 PD Power Down (Logic 0: normal mode; Logic 1: Power-Down mode)

12 NC Internally not connected

13 FS Full Scale selection (Logic 0: 2g Full-scale; Logic 1: 6g Full-scale)

14-15 Reserved Leave unconnected or connect to Vdd

16 Reserved Connect to Vdd or ground

17 Reserved Leave unconnected or connect to Vdd

18 Reserved Leave unconnected or connect to ground

19 to 24 NC Internally not connected

DIRECTION OF THE

DETECTABLE

ACCELERATIONS

Vdd

GND

Vouty

ST RESERVED

RESERVED

NC1

Voutx RESERVED

D05IN1544

PD RESERVED11 14

1312NC FS

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LIS2L02AS4

Table 3. Mechanical Characteristics1

(Temperature range -40°C to +85°C). All the parameters are specified @ Vdd =3.3V, T=25°C unless

otherwise noted

Notes: 1. The product is factory calibrated at 3.3V. The device can be powered from 2.4V to 5.25V. 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*π*110KΩ*Cload) with Cload>1nF.

Symbol Parameter Test Condition Min. Typ.2Max. Unit

Ar Acceleration Range3FS pin connected

to GND

±1.8 ±2.0 g

FS pin connected

to Vdd

±5.4 ±6.0 g

So Sensitivity4Full-scale = 2g Vdd/5–10% Vdd/5 Vdd/5+10% V/g

Full-scale = 6g Vdd/15–10% Vdd/15 Vdd/15+10% V/g

SoDr Sensitivity Change Vs

Temperature

Delta from +25°C ±0.01 %/°C

Voff Zero-g Level4T = 25°C Vdd/2-10% Vdd/2 Vdd/2+10% V

OffDr Zero-g level Change Vs

Temperature

Delta from +25°C ±0.2 mg/°C

NL Non Linearity5Best fit straight line

Full-scale = 2g

X, Y axis

±0.3 ±1.5 % FS

CrossAx Cross-Axis6±2±4%

An Acceleration Noise Density Vdd=3.3V;

Full-scale = 2g

30 µg/

Vt Self test Output Voltage

Change7,8,9

T = 25°C

Vdd=3.3V

Full-scale = 2g

X axis

-20 -50 -100 mV

T = 25°C

Vdd=3.3V

Full-scale = 2g

Y axis

20 50 100 mV

Fres Sensing Element Resonance

Frequency10

all axes 1.5 kHz

Top Operating Temperature Range -40 +85 °C

Wh Product Weight 0.6 gram

LIS2L02AS4

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Table 4. Electrical Characteristics1

(Temperature range -40°C to +85°C) All the parameters are specified @ Vdd =3.3V, T=25°C unless oth-

erwise noted

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*π*110KΩ*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 Parameter Test Condition Min. Typ.2Max. Unit

Vdd Supply Voltage 2.4 3.3 5.25 V

Idd Supply Current mean value

PD pin connected

to GND

0.85 1.5 mA

IddPdn Supply Current in Power

Down Mode

rms value

PD pin connected

to Vdd

25µA

Vst Self Test Input Logic 0 level 0 0.8 V

Logic 1 level 2.2 Vdd V

Rout Output Impedance 80 110 140 kΩ

Cload Capacitive Load Drive3320 pF

Ton Turn-On Time at exit from

Power Down mode

Cload in µF 550*Cload+0.3 ms

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, Not powered) 3000g for 0.5 ms

10000g for 0.1 ms

TSTG Storage Temperature Range -40 to +125 °C

ESD Electrostatic Discharge Protection 2 (HBM) kV

200 (MM) V

1500 (CDM) V

This is an ESD sensitive device, improper handling can cause permanent damages to the part

This is a Mechanical Shock sensitive device, improper handling can cause permanent damages to the part

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LIS2L02AS4

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 Sen-

sitivity 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 in-

terface 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.

LIS2L02AS4

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4 Functionality

The LIS2L02AS4 is a high performance, low-power, analog output two axes linear accelerometer pack-

aged 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 pack-

aging 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 re-

sponse 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 process-

ing chain uses a fully differential structure. The final stage converts the differential signal into a single-end-

ed 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 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 (zero-g level, sensitivity and self-test) are ratiometric to the supply voltage. In-

creasing 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 param-

eters 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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LIS2L02AS4

5 Application hints

Figure 4. LIS2L02AS4 Electrical Connection

Power supply decoupling capacitors (100nF ceramic + 10

F Al) should be placed as near as possible to

the device (common design practice).

The LIS2L02AS4 allows to band limit Voutx, Vouty through the use of external capacitors. The recom-

mended 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 cut-off fre-

quency (ft) of the external filters is:

Taking in account that the internal filtering resistor (Rout) has a nominal value equal to 110kΩ, the equation

for the external filter cut-off frequency may be simplified as follows:

The tolerance of the internal resistor can vary typically of ±20% within its nominal value of 110kΩ; thus the

cut-off frequency will vary accordingly. A minimum capacitance of 320 pF for Cload(x, y) is required in any

case.

100nF10µF

Vdd

Vout X

GND

GND GND

Cload x

Cload y

Optional

Optional Vout Y

PD FS

Digital signals

11 14

1312

LIS2L02AS4

(top view)

DIRECTION OF THE

DETECTABLE

ACCELERATIONS

GND

2πRout Cload xy,()⋅⋅

----------------------------------------------------------------=

1.45µF

Cload xy,()

-------------------------------Hz[]=

LIS2L02AS4

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Table 6. Filter Capacitor Selection, Cload (x,y,z). Capacitance Value Choose.

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

Figure 5 refers to LIS2L02AS4 device powered at 3.3V

Cut-off frequency Capacitor value

1 Hz 1500nF

10 Hz 150nF

50 Hz 30 nF

100 Hz 15 nF

200 Hz 6.8 nF

500 Hz 3 nF

TOP VIEW

X=2.31V (+1g)

Y=1.65V (0g)

Earth’s Surface

X=0.99V (-1g)

Y=1.65V (0 g)

X=1.65V (0g)

Y=0.99V (-1g)

X=1.65V (0g)

Y=2.31V (+1g)

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LIS2L02AS4

6 Typical performance Characteristics

6.1 Mechanical Characteristics at 25°C

Figure 6. X axis Zero g Level at 3.3V

Figure 7. Y axis Zero g Level at 3.3V

Figure 8. X axis Sensitivity at 3.3V

Figure 9. Y axis Sensitivity at 3.3V

1.55 1.6 1.65 1.7 1.75

Zerog Level (V)

Percent of parts (%)

1.55 1.6 1.65 1.7 1.75

Zerog Level (V)

Percent of parts (%)

0.62 0.63 0.64 0.65 0.66 0.67 0.68 0.69 0.7

Sensitivity (V/g)

Percent of parts (%)

0.62 0.63 0.64 0.65 0.66 0.67 0.68 0.69 0.7

Sensitivity (V/g)

Percent of parts (%)

LIS2L02AS4

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6.2 Mechanical Characteristics derived from measurement in the -40°C to +85°C temperature

range

Figure 10. X axis Zero g Level Change Vs.

Temperature

Figure 11. Y axis Zero g Level Change Vs.

Temperature

Figure 12. X axis Sensitivity Change Vs.

Temperature

Figure 13. Y axis Sensitivity Change Vs.

Temperature

2 1.5 1 0.5 0 0.5 1 1.5 2

Zerog level change (mg/deg. C)

Percent of parts (%)

2 1.5 1 0.5 0 0.5 1 1.5 2

0g level change (mg/deg. C)

Percent of parts (%)

0.03 0.02 0.01 0 0.01 0.02

Sensitivity Change(%/deg. C)

Percent of parts (%)

0.03 0.02 0.01 0 0.01 0.02

Sensitivity Change (%/deg. C)

Percent of parts (%)

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LIS2L02AS4

6.3 Electrical Characteristics at 25°C

Figure 14. Noise density at 3.3V

Figure 15. Current consumption at 3.3V

Figure 16. Current consumption in power

down mode at 3.3V

18 20 22 24 26 28 30 32

Noise density (ug/sqrt(Hz))

Percent of parts (%)

0.4 0.6 0.8 1 1.2 1.4

current consumption (mA)

Percent of parts (%)

1.2 1.3 1.4 1.5 1.6 1.7 1.8

current consumption (uA)

Percent of parts (%)

LIS2L02AS4

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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 17. SO24 Mechanical Data & Package Dimensions

OUTLINE AND

MECHANICAL DATA

DIM.

mm inch

MIN. TYP. MAX. MIN. TYP. MAX.

A 2.35 2.65 0.093 0.104

A1 0.10 0.30 0.004 0.012

B 0.33 0.51 0.013 0.200

C 0.23 0.32 0.009 0.013

(1)

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

L 0.40 1.27 0.016 0.050

k 0˚ (min.), 8˚ (max.)

ddd 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

Weight: 0.60gr

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LIS2L02AS4

8 Revision History

Table 7. Revision History

Date Revision Description of Changes

February 2004 1 First issue

1-Dec-2005 2 Changed from Product preview to Datasheet maturity.

Added Typical performance Characteristics section.

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

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LIS2L02AS4