Mechanical and electrical specifications

LISY300AL

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2.4

Terminology

2.4.1

Sensitivity

A yaw rate gyroscope is a Z-axis rate device that produces a positive-going output voltage

for counterclockwise rotation around the axis normal to the package top. Sensitivity

describes the gain of the sensor and can be determined by applying a defined angular

velocity to it. This value changes very little over temperature and also very little over time.

2.4.2

Zero-rate level

Zero-rate level describes the actual output signal if there is no angular rate present. For a

3.3 V powered sensor the absolute zero-rate output is ideally 1.65 V. Zero-rate level of

precise MEMS sensors is, to some extent, a result of stress to the sensor and therefore

zero-rate level can slightly change after mounting the sensor onto a printed circuit board or

after exposing it to extensive mechanical stress. This value changes very little over

temperature and also very little over time.

2.4.3

Self-test

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 to Vdd, an actuation force is

applied to the sensor, emulating a definite Coriolis force. In this case the sensor output will

exhibit a voltage change in its DC level which is also depending on the supply voltage. When

ST is active, the device output level is given by the algebraic sum of the signals produced by

the velocity acting on the sensor and by the electrostatic test-force. If the output signals

change within the amplitude specified in Table 3, then the mechanical element is working

properly and the parameters of the interface chip are within the defined specification.