LIS3LV02DL datasheet(19/48 Pages) STMICROELECTRONICS

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LIS3LV02DL

Functionality

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Functionality

The LIS3LV02DL is a high performance, low-power, digital output 3-axis linear

accelerometer packaged in an 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 a signal to the external world through an I2C/SPI serial interface.

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

The complete measurement chain is composed by a low-noise capacitive amplifier which

converts into an analog voltage the capacitive unbalancing of the MEMS sensor and by

three

Σ∆ analog-to-digital converters, one for each axis, that translate the produced signal

into a digital bitstream.

The

Σ∆ converters are coupled with dedicated reconstruction filters which remove the high

frequency components of the quantization noise and provide low rate and high resolution

digital words.

The charge amplifier and the

Σ∆ converters are operated respectively at 61.5 kHz and

20.5 kHz.

The data rate at the output of the reconstruction depends on the user selected Decimation

Factor (DF) and spans from 40 Hz to 2560 Hz.

The acceleration data may be accessed through an I2C/SPI interface thus making the

device particularly suitable for direct interfacing with a microcontroller.

The LIS3LV02DL features a Data-Ready signal (RDY) which indicates when a new set of

measured acceleration data is available thus simplifying data synchronization in digital

system employing the device itself.

The LIS3LV02DL may also be configured to generate an inertial Wake-Up, Direction

Detection and Free-Fall interrupt signal accordingly to a programmed acceleration event

along the enabled axes.

LIS3LV02DL Datasheet(PDF) 19 Page - STMicroelectronics

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