LIS332AX STMicroelectronics, LIS332AX Datasheet - Page 9

• Manufacturer Part Number: LIS332AX
• Description: Board Mount Accelerometers MEMS 3-Axis 2g Absolute Analog
• Manufacturer: STMicroelectronics

Specifications of LIS332AX

• Sensing Axis: X, Y, Z
• Acceleration: 2 g
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 2.16 V
• Supply Current: 300 uA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Digital Output - Bus Interface: IC
• Mounting Style: SMD/SMT
• Sensitivity: 0.363 V/g
• Package / Case: LGA-16
• Output Type: Linear
• Package Type: LGA
• Operating Supply Voltage (min): 2.16V
• Operating Supply Voltage (typ): 3V
• Operating Supply Voltage (max): 3.6V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 3mm
• Product Height (mm): 1mm
• Product Length (mm): 3mm
• Mounting: Surface Mount
• Pin Count: 16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LIS332AX
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5.1
5.2
5.3
Functionality
The LIS332AX is a 3-axis ultracompact low-power, analog output linear 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 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 absolute with respect to
the voltage supply. Increasing or decreasing the voltage supply will not cause a change in
the sensitivity and the offset. The feature allows the coupling of the sensor with an ADC,
having a fixed voltage reference independent from Vdd.
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 16932 Rev 1
Functionality
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