Mechanical and electrical specifications

LIS2L06AL

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Self Test allows to test the mechanical and electric part of the sensor, allowing the seismic

mass to be moved by means of an electrostatic test-force. The Self Test function is off when

the ST pin is connected to GND. When the ST pin is tied at Vdd an actuation force is applied

to the sensor, simulating a definite input acceleration. In this case the sensor outputs will

exhibit a voltage change in their DC levels which is related to the selected full scale and

depending on the Supply Voltage through the device sensitivity. When ST 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 inside Table 2, than the sensor is working properly and the

parameters of the interface chip are within the defined specification.

Output impedance describes the resistor inside the output stage of each channel. This

resistor is part of a filter consisting of an external capacitor of at least 1nF and the internal

resistor. Due to the high resistor level only small, inexpensive external capacitors are

needed to generate low corner frequencies. When interfacing with an ADC it is important to

use high input impedance input circuitries to avoid measurement errors. Note that the

minimum load capacitance forms a corner frequency beyond the resonance frequency of

the sensor. For a flat frequency response a corner frequency well below the resonance

frequency is recommended. In general the smallest possible bandwidth for an particular

application should be chosen to get the best results.