5/9

LIS3L02AQ

3

FUNCTIONALITY

The LIS3L02AQ is a low-cost, low-power, analog output three-axis linear accelerometer packaged in QFN pack-

age. 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

The THELMA process is utilized 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

free to move on a plane parallel to the substrate itself. To be compatible with the traditional packaging tech-

niques 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 figure below; when a linear acceleration is applied,

the proof mass displaces from its nominal position, causing an imbalance in the capacitive half-bridge. This im-

balance is measured using charge integration in response to a voltage pulse applied to the sense capacitor.

Figure 4. Equivalent electrical circuit

S1x

rot

S2x

S1y

S2y

S1z

S2z