LSM330D Datasheet, PDF (20/66 Pages) STMicroelectronics – Low power mode

Functionality
4
Functionality
LSM330D
The LSM330D is a system-in-package featuring a 3D digital accelerometer and a 3D digital
gyroscope.
The device includes specific sensing elements and two IC interfaces capable to measuring
both the acceleration and angular rate applied to the module and to provide a signal to
external applications through an SPI/I²C serial interface.
The various sensing elements are manufactured using specialized micromachining
processes, while the IC interfaces are developed using a CMOS technology that allows the
design of a dedicated circuit which is trimmed to better match the sensing element
characteristics.
The LSM330D may also be configured to generate an inertial wakeup and free-fall interrupt
signal according to a programmed acceleration event along the enabled axes.
4.1
4.1.1
4.1.2
Accelerometer
Normal mode, Low power mode
The accelerometer sensor inside the LSM330D inertial module provides two different
operating modes: Normal mode and Low power mode. Normal mode guarantees high
resolution, while Low power mode further reduces current consumption.
The table below summarizes how to select the operating mode and the corresponding
characteristics.
Table 9. Operating mode selection
Operating mode
CTRL_REG1[3]
(LPen bit)
Low power mode (8-bit)
1
Normal mode (12-bit)
0
CTRL_REG4[3]
(HR bit)
0
1
BW [Hz]
ODR/2
ODR/9
Turn-on time [ms]
1
7/ODR(kHz)
Self-test
Self-test allows the checking of sensor functionality without moving it. The self-test function
is off when the self-test bit (ST) is programmed to ‘0’. When the self-test bit is programmed
to ‘1’ an actuation force is applied to the sensor, simulating a definite input acceleration. In
this case, the sensor outputs exhibit a change in their DC levels which are related to the
selected full scale through the device sensitivity. When self-test is activated, the device
output level is given by the algebraic sum of the signals produced by the acceleration acting
on the sensor and by the electrostatic test-force. If the output signals change within the
amplitude specified in Table 3, then the sensor is working properly and the parameters of
the interface chip are within the defined specifications.
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Doc ID 022562 Rev 2