Sensor output processing device having self-diagnosis function
AssigneeDenso Corporation
InventorShoichi Ishida
Life of this patent
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Abstract
A sensor output processing device has an amplifier circuit for amplifying a sensor output signal of a sensor and a buffer circuit for limiting the amplified signal to a high limit level lower than a high side voltage of a power source or a low limit level higher than a low side voltage of the power source. This limited signal is normally produced as an output signal to an external circuit. When a self-diagnosis circuit determines an abnormality in the sensor or in the amplifier circuit and the buffer circuit, the output signal is fixed to a level higher than the high limit level or lower than the low limit level.
Claims5
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 an output signal variable with the sensor output signal;
- an output terminal for applying the 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 the signal processing circuit limits the output signal to either a high limit level lower than the high side voltage or a low limit level higher than the low side voltage, when no abnormality determination signal is produced by the self-diagnosis circuit, and
- wherein the signal processing circuit fixes the output signal to be 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.
Dependencies are inferred from the claim text.