LIS2DUXS12 datasheet(14/104 Pages) STMICROELECTRONICS

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3.3

Sensing element

A proprietary process is used to create a surface micromachined accelerometer. The technology allows

processing 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. In order 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 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 capacitor.

At steady-state the nominal value of the capacitors are a few pF and when an acceleration is applied, the

maximum variation of the capacitive load is in the fF range.

3.4

IC interface

The complete measurement chain is composed of a low-noise capacitive amplifier which converts the capacitive

unbalancing of the MEMS sensor into an analog voltage using an analog-to-digital converter.

The acceleration data may be accessed through an I²C/SPI/MIPI I3C® interface thus making the device

particularly suitable for direct interfacing with a microcontroller.

The LIS2DUXS12 features a data-ready signal which indicates when a new set of measured acceleration data is

available, thus simplifying data synchronization in the digital system that uses the device.

3.5

Factory calibration

The IC interface is factory-calibrated for sensitivity (So) and zero-g level offset.

The trim values are stored inside the device in nonvolatile memory. Any time the device is turned on, the trimming

parameters are downloaded into the registers to be used during active operation. This allows using the device

without further calibration. If an accidental write occurs in the registers where the trimming parameters are stored,

the BOOT bit in CTRL4 (13h) can help to retrieve the correct trimming parameters from nonvolatile memory

without the need to switch on/off the device. This bit is automatically reset at the end of the download operation.

Setting this bit has no impact on the control registers.

3.6

Temperature sensor

The temperature is available in OUT_T_AH_QVAR_L (2Eh), OUT_T_AH_QVAR_H (2Fh) stored as two's

complement data, left-justified in 12-bit mode.

Refer to Table 5. Temperature sensor characteristics for the conversion factor.

3.7

Analog hub functionality

The LIS2DUXS12 embeds an analog hub sensing functionality which is able to connect an analog input and

convert it to a digital signal for embedded processing.

In the LIS2DUXS12, the analog hub has a dedicated channel that can be activated by setting the AH_QVAR_EN

bit to 1 in the AH_QVAR_CFG (31h) register.

The AH_QVAR_NOTCH_EN bit and the AH_QVAR_NOTCH_CUTOFF bit in the AH_QVAR_CFG (31h) register

are used, respectively, to enable/disable the embedded digital notch filter and to set the cut-off frequency of this

filter (50 Hz or 60 Hz).

Analog hub data are available as two's complement data, left-justified in 12-bit mode in the OUT_T_AH_QVAR_H

(2Fh) and OUT_T_AH_QVAR_L (2Eh) registers and are generated at the same rate as the one set for the

accelerometer sensor through the ODR[3:0] bits in register CTRL5 (14h).

Analog signal data can be also processed by MLC/FSM logic.

LIS2DUXS12

Sensing element

DS14035 - Rev 2

page 14/104

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