LPY510AL Terminology
Doc ID 15805 Rev 2 7/12
3 Terminology
3.1 Sensitivity
An angular rate gyroscope is a device that produces a positive-going output voltage for
counterclockwise rotation around the sensible 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. 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 dependent 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.
3.4 High pass filter reset (HP)
LPY510AL provides the possibility to reset the optional external high pass filter by applying
high logic value to HP pad. This procedure ensures faster response expecially during
overload conditions. Moreover, this operation is suggested each time the device is powered.
