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