INPUT STAGE OF A SIGNAL-PROCESSING UNIT

摘要

The invention relates to an input stage of a processing unit. The inventive input stage comprises an input (A1) which is polarised at a polarising voltage corresponding to a pre-determined fraction of a supply voltage (Vcc). The voltage from the polarised input (A1) is compared to at least two voltage thresholds (S1, S2) which are greater than and less than the polarising voltage respectively, such as to supply a processing circuit (3) with at least 2 bits (B1, B2) which are representative of the type of sensor (2) or automaton that is connected to the input (A1) of the input stage and of the state thereof. Moreover, a filter (5) is disposed between the polarised input (A1) and the comparators (4a, 4b). In this way, a good level of immunity to man-made noise can be maintained, without interfering with the transmission of signals, with smooth variation, originating from an industrial sensor which is connected to the input (A1).