LIS331ALTR STMicroelectronics, LIS331ALTR Datasheet - Page 11
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LIS331ALTR
Manufacturer Part Number
LIS331ALTR
Description
IC ACCELEROMETER 3AXIS 16-LGA
Manufacturer
STMicroelectronics
Datasheet
1.STEVAL-MKI021V1.pdf
(16 pages)
Specifications of LIS331ALTR
Axis
X, Y, Z
Acceleration Range
±2g
Sensitivity
0.145 x Vdd = V/g
Voltage - Supply
3 V ~ 3.6 V
Output Type
Analog
Bandwidth
2kHz
Interface
IC
Mounting Type
Surface Mount
Package / Case
16-LGA
Sensing Axis
X, Y, Z
Acceleration
2 g
Supply Voltage (max)
3.6 V
Supply Voltage (min)
3 V
Supply Current
0.65 mA
Maximum Operating Temperature
+ 85 C
Minimum Operating Temperature
- 40 C
Shutdown
Yes
For Use With
497-10048 - BOARD EVAL ACCELEROMETER497-8205 - BOARD EVALUATION LIS331AL
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
497-8333-2
LIS331ALTR
LIS331ALTR
LIS331AL
3
3.1
3.2
3.3
Functionality
The LIS331AL is a nano low-power, analog output three-axis linear accelerometer packaged
in a 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 an analog signal to the
external world.
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 in fF range.
IC Interface
The complete signal processing uses a fully differential structure, while the final stage
converts the differential signal into a single-ended one to be compatible with the external
world.
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 produced signal 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 will
increase or decrease linearly. The feature provides the 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 inside the device by a non volatile structure. Any time the
device is turned on, the trimming parameters are downloaded into the registers to be
employed during the normal operation. This allows the user to employ the device without
further calibration.
Functionality
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