LIS332AR STMicroelectronics, LIS332AR Datasheet - Page 9

• Manufacturer Part Number: LIS332AR
• Description: Board Mount Accelerometers Digital 2.4v - 3.3v 100 Noise 0.3mA
• Manufacturer: STMicroelectronics

Specifications of LIS332AR

• Sensing Axis: X, Y, Z
• Acceleration: 2 g
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 2.16 V
• Supply Current: 0.3 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Shutdown: Yes
• Sensitivity: 0.6 V/g
• Package / Case: LGA-16
• Output Type: Analog - Voltage
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LIS332AR
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5.1
5.2
5.3
Functionality
The LIS332AR is a 3-axis ultracompact, low-power, analog output accelerometer packaged
in an LGA package. The complete device includes a sensing element and an IC interface
capable of taking information from the sensing element and providing an analog signal to
the external world.
Sensing element
A proprietary process is used to create a surface micro-machined accelerometer. The
technology allows the creation of suspended silicon structures which are attached to the
substrate at several points called “anchors” and are free to move in the direction of the
sensed acceleration. To be compatible with traditional packaging techniques, a cap is
placed on top of the sensing element to prevent blocking of the moving parts during the
moulding phase of plastic encapsulation.
When an acceleration is applied to the sensor, the proof mass shifts 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 a few pF, and when an acceleration
is applied the maximum variation of the capacitive load is in the fF range.
IC interface
The complete signal processing utilizes a fully differential structure, while the final stage
converts the differential signal into a single-ended signal to be compatible with external
applications.
The first stage is a low-noise capacitive amplifier that implements a correlated double
sampling (CDS) at its output to cancel the offset and the 1/f noise. The signal produced is
then sent to three different S&Hs, one for each channel, and made available to the outside.
All the analog parameters (output offset voltage and sensitivity) are ratiometric to the
voltage supply. Increasing or decreasing the voltage supply, the sensitivity and the offset
increases or decreases linearly. This feature provides for cancellation of the error related to
the voltage supply along an analog-to-digital conversion chain.
Factory calibration
The IC interface is factory-calibrated for sensitivity (So) and Zero-g level (Voff). The trimming
values are stored in the device in a non-volatile structure. Any time the device is turned on,
the trimming parameters are downloaded to the registers to be employed during normal
operation. This allows the user to use the device without further calibration.
Doc ID 16931 Rev 1
Functionality
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