Patent ID: 6940290
Filing Date: 2005-09-06
Classification: G01D,G01R

Abstract:
1. A sensor output processing device for a sensor comprising: a pair of power supply terminals for supplying a high side voltage and a low side voltage, respectively, to provide a power voltage; a signal processing circuit, operable with the power voltage, for amplifying a sensor output signal produced by the sensor and producing a circuit output signal variable with the sensor output signal; an output terminal for applying the circuit output signal to an external circuit; and a self-diagnosis circuit, operable with the power voltage, for diagnosing operations of at least one of the sensor and the signal processing circuit based on potentials therein and producing an abnormality determination signal indicative of an abnormality, wherein, if the circuit output signal exceeds a high limit level lower than the high side voltage or is lower than a low limit level higher than the low side voltage, and irrespective of the sensor output signal, the signal processing circuit limits the circuit output signal to either the high limit level lower than the high side voltage or the low limit level higher than the low side voltage, when no abnormality determination is produced by the self-diagnosis circuit, and wherein the signal processing circuit fixes the circuit output signal to be a fixed level higher than the high limit level or lower than the low limit level, when the abnormality determination signal is produced by the self-diagnosis circuit.