lis3l02ds STMicroelectronics, lis3l02ds Datasheet - Page 5

• Manufacturer Part Number: lis3l02ds
• Description: Three Axis 2g-6g Linear Accelerometer
• Manufacturer: STMicroelectronics

1
1.1 Sensing element
The THELMA process is utilized to create a surface micro-machined accelerometer. The technology al-
lows to carry out suspended silicon structures which are attached to the substrate in a few points called
anchors 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 of the sensing element to avoid blocking the moving parts
during the molding phase.
The equivalent circuit for the sensing element 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.
Figure 1. Equivalent electrical circuit
FUNCTIONALITY
C
C
C
C
C
C
C
C
C
pr
ps1
ps2
pr
pr
ps1
ps2
ps1
ps2
C
C
C
C
C
C
s1x
s2x
s1y
s2y
s1z
s2z
R
R
R
R
R
R
R
R
R
s1
r
s2
s1
r
s2
s1
r
s2
S2x
S1x
S2y
S2z
S1y
S1z
rot
LIS3L02DS
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