LIS2L02AL STMICROELECTRONICS | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 17
Technical content
Datasheet sections
- 1 Block Diagram & Pins Description
- 1.1 Block diagram
- 1.2 Pin Description
- 2 Mechanical and Electrical Specifications
- 2.1 Mechanical Characteristics
- 2.2 Electrical Characteristics
- 2.3 Absolute maximum ratings
- 2.4 Terminology
- 3 Functionality
- 3.1 Sensing element
- 3.2 IC Interface
- 3.3 Factory calibration
- 4 Application hints
- 4.1 Soldering information
- 4.2 Output Response vs Orientation
- 5 Typical performance characteristics
- 5.1 Mechanical Characteristics at 25°C
- 5.2 Mechanical Characteristics derived from measurement in the
- 5.3 Electrical characteristics at 25°C
- 6 Package Information
- 7 Revision history
Features
■ 2.4V TO 5.25V SINGLE SUPPLY OPERATION ■ LOW POWER CONSUMPTION ■ ±2g FULL-SCALE ■ 0.3mg RESOLUTION OVER 100Hz BANDWIDTH ■ EMBEDDED SELF TEST ■ OUTPUT VOLTAGE, OFFSET AND SENSITIVITY RATIOMETRIC TO THE SUPPLY VOLTAGE ■ HIGH SHOCK SURVIVABILITY ■ ECO-PACK COMPLIANT
Description
The LIS2L02AL is a low-power 2-axis linear capacitive 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 acceleration, is manufactured using a dedicated process 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 LIS2L02AL has a full scale of ±2g and it is capable of measuring accelerations over a bandwidth of 2.0 kHz for all axes. The device bandwidth may be reduced by using external capacitances. A self-test capability allows to check the mechanical and electrical signal path of the sensor. The LIS2L02AL is available in plastic SMD package and it is guaranteed to operate over an extended temperature range of -40°C to +85°C. The LIS2L02AL 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. Order codes LGA-8 Part number Temp range, °C Package Packing LIS2L02AL -40°C to +85°C LGA-8 Tray LIS2L02ALTR -40°C to +85°C LGA-8 T ape & Reel
1 Block Diagram & Pins Description
1.1 Block diagram
Figure 1. Block Diagram
1.2 Pin Description
Figure 2. Pin Connection
1 Block Diagram & Pins Description LIS2L02AL
Table 1. Pin description
1 ST Self T est (Logic 0: normal mode; Logic 1: Self-test)
2 NC Not connected
3 GND 0V supply
4 Reserved Leave unconnected
5 Reserved Leave unconnected
6 Vouty Output Voltage Y channel
7 Voutx Output Voltage X channel
8 Vdd Power supply
2 Mechanical and Electrical Specifications
2.1 Mechanical Characteristics
Table 2. Mechanical Characteristics 1 T = 25°C unless otherwise noted. 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
5 Guaranteed by design
2 Mechanical and Electrical Specifications LIS2L02AL
6 Contribution to the measuring output of the inclination/acceleration along any perpendicular
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
2.2 Electrical Characteristics
Table 3. Electrical Characteristics 1
2.3 Absolute maximum ratings
Table 4. Absolute maximum ratings
2.4 Terminology
Sensitivity Tolerance describes the range of Sensitivities of a large population of sensors. 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 Table 2, than 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 723pF 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.
3 Functionality
The LIS2L02AL is a high performance, low-power, analog output 2-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 to 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 up to 100fF .
3.2 IC Interface
In order to increase robustness and immunity against external disturbances the complete signal processing chain uses a fully differential structure. The final stage converts the differential signal into a single-ended 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 system (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. Increasing 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.
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.
4 Application hints LIS2L02AL
4 Application hints
Figure 3. LIS2L02AL Electrical Connection placed as near as possible to the device (common design practice). The LIS2L02AL allows to band limit Voutx and Vouty through the use of external capacitors. Cload(x, y) is required in any case.
Table 5. Filter Capacitor Selection, C load (x,y).
4.1 Soldering information
for soldering heat resistance according to JEDEC J-STD-020C. Land pattern and soldering recommendations are available upon request.
4.2 Output Response vs Orientation
Figure 4. Output Response vs Orientation
1 Hz 1500 nF
10 Hz 150 nF
20 Hz 68 nF
50 Hz 30 nF
100 Hz 15 nF
500 Hz 3 nF
5 T ypical performance characteristics LIS2L02AL
5 Typical performance characteristics
5.1 Mechanical Characteristics at 25°C
Figure 5. x-axis Zero-g level at 3.3V Figure 6. y-axis Zero-g level at 3.3V Figure 7. x-axis sensitivity at 3.3V Figure 8. y-axis sensitivity at 3.3V
5.2 Mechanical Characteristics derived from measurement in the
Figure 9. x-axis Zero-g level change Vs Figure 10. y-axis Zero-g level change Vs Figure 11. x-axis sensitivity change Vs Figure 12. y-axis sensitivity change Vs
5.3 Electrical characteristics at 25°C
Figure 13. Noise density at 3.3V (x,y axis) Figure 14. Current consumption at 3.3V
6 Package Information
In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. Figure 15. LGA-8 Mechanical Data & Package Dimensions
7 Revision history LIS2L02AL
7 Revision history
26-Sep-2005 1 Initial release.
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the co nsequences 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 publicati on are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics prod ucts are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectro nics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners © 2005 STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Ital y - Japan - Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America