Terminology LYPR540AH
8/12 Doc ID 16747 Rev 1
3 Terminology
3.1 Sensitivity
An angular rate gyroscope is a device that produces a positive-going output voltage for
counterclockwise rotation around the sensitive axis considered. 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 time.
3.2 Zero-rate level
Zero-rate level describes the actual output signal if there is no angular rate present. The
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 time.
3.3 Self-test
Self-test allows testing the mechanical and electrical 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 angular velocity acting on the sensor and by the electrostatic test-force. If the output
signals change within the amplitude specified then the mechanical element is working
properly and the parameters of the interface chip are within the defined specification.
