UM0249 User guide
EK3L02AL Evaluation Kit
Introduction
The EK3L02AL is an Evaluation Kit designed to provide the user with a complete, ready-touse platform for the evaluation of the LIS3L02AL, a low-power 3-Axis linear capacitive accelerometer that includes a sensing element and an IC interface able to take information from the sensing element and to provide an analog signal to the external world. Besides the MEMS sensor, the system mounts a linear voltage regulator and a rail to rail Low noise Quad amplifier configured as non-inverting buffer thus making both direct sensor outputs and buffered sensor outputs available to the user. The kit provides also an easy way to control its Self-Test (ST) pin.
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June 2006
Rev 1
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Contents
EK3L02AL user guide
Contents
1 Evaluation Kit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 1.2 Operating the Evaluation Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Driving ST signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.1 Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 3 4
Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Bill Of Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
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EK3L02AL user guide
Evaluation Kit Description
1
Evaluation Kit Description
The EK3L02AL is an Evaluation Kit designed to provide the user with a complete, ready-touse platform for the evaluation of the LIS3L02AL 3-axis analog output linear accelerometer. The block diagram of the evaluation kit and the top silk-screen of the board are shown respectively in Figure 1 and Figure 2 while the photo of the full board is given in Figure 3. Figure 1. Evaluation Board Block Diagram
PS
Voltage Regulator
3.3V MEMS Sensor Self Test
PSR
Output Buffer
VXYZ Buffered Output
Voutxyz
Figure 2.
Top silk-screen for EK3L02AL board layout
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Sensor
Output
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Evaluation Kit Description Figure 3. Board photograph
EK3L02AL user guide
1.1
Operating the Evaluation Kit
To operate the evaluation kit it is necessary to supply it through the connector marked as J1 (PS) with a dc voltage comprised between 3.7V and 18V. The suggested supply voltage is 5V. The typical current consumption of the LIS3L02AL MEMS sensor is 0.85 mA while the typical current consumption of the whole board is in the range of 6 mA. The voltage applied to the board is then regulated through a linear voltage regulator which supplies the MEMS sensor at 3.3V. The outputs (Voutx, Vouty and Voutz) of the LIS3L02AL linear accelerometer are band limited through the usage of three capacitors Cx, Cy and Cz of 1.5nF which, together with the output resistance Rout=110K of the sensor, create a single-pole low-pass filter having a cut-off frequency of about 1KHz.
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In case a different cut-off frequency ft is required, the above capacitances must be replaced by the users with other components having the value given by the following formula: 1 C ( x, y, x ) = ----------------------------------2 Ro u t ft
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As anticipated above, the EK3L02AL makes both the direct sensor outputs and the buffered signals available to the outside through two different connectors which are named respectively J4 (Sensor output) and J3 (Buffered output). In particular the three channels are made available going from the left to right of the board in the order Voutx, Vouty and Voutz. The buffering of the sensor outputs is obtained though the usage of a rail-to-rail low-noise quad-amplifier configured as non-inverting buffer.
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EK3L02AL user guide
Evaluation Kit Description
1.2
Driving ST signal
The board allows to control ST (Self Test) signal through the usage of a test point (marked J7) and a jumper.
1.2.1
Self-Test
When the jumper related to J7 (ST) is either inserted as marked highlighted by the red box in Figure 2 or completely removed from the board the self-test feature is disabled. In order to activate the self-test feature the afore said jumper must be into J7 so to shortcircuit its central and upper pins. When this function is activated the seismic mass of the sensor is moved by means of an electrostatic test-force simulating a definite input acceleration. Under these conditions the sensor outputs will exhibit a voltage change in their DC levels as specified in the datasheet of the LIS3L02AL sensor.
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2
1 2 3
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1 2 3 ST Vou tZ Rsv d GN D 4 Vou tY Rsvd Vd d 1 Vou tX Vou tZ 2 3 Cz 1n 5F J7 5
Self Test
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Schematic Diagram
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J3 TS92 4 rail to rail Low noise Qu ad operational amplifier VX VY VZ 1 2 3 J4 Vou tX Vou tY Vou tZ U3 VX Vou tX Vou tY VY TS92 4 VDD 1 2 3
LE 33 linear voltage regulator case: SO8 or TO92
U1 LE 33
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Figure 4.
Schematic Diagram
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Buffered Output
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Senso r Output
VDD J1 C2 10 0nF Power_Su ppl y 1 2
J2
U2
1 2
ps r
C1 2.2 uF
1 1 2 2 3 3 4 4
8 8 7 7 6 6 5 5
1 2 3 4 5 6 7 VOU T1 V-1 V+1 VCC V+2 V-2 VOU T2 VOU T4 V-4 V+4 GN D V+3 V-3 VOU T3
14 13 12 11 10 9 8
Vou tZ VZ
LE 33
Schematic diagram for EK3L02AL board
so Ob VDD + C4 10 0nF C3 1u F
The schematic diagram of the EK3L02AL evaluation kit is shown in Figure 4.
EK3L02AL user guide
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VDD 7 Vou tX
U4 LIS3L 02AL
6 Vou tY
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EK3L02AL user guide
Bill Of Material
3
Bill Of Material
The Bill of Material for EK3L02AL evaluation kit is given in Table 1 Table 1. Bill Of Material
Item 1 2 3 4 5 6 7 8 9 Quantity 2 1 3 1 2 3 1 1 1 Reference C2,C4 C1 Cx,Cy,Cz C3 J1,J2 J3,J4,J7 U2 U3 U4 Value 100nF 2.2uF 1.5nF 1uF CON2 CON3 LE33
TS924
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Revision History
EK3L02AL user guide
4
Revision History
Table 2.
Date 07-Jun-2006
Document revision history
Revision 1 Initial release. Changes
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EK3L02AL user guide
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