Positive, Negative and Floating Input Voltage Level Detector With Testing Features
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
This dual and floating detector (Fig. 1) includes a voltage comparator and positive and negative power supplies. The comparator inputs are pre-biased in differential mode by means of a dual reference source (Ref -+) and three resistors : Rdiff, R.Refand R.Ref-. When the differential floating voltage to be detected is applied to its inputs, the prebiasing differential voltage is progressively canceled and then reversed, thus turning the voltage comparator to switch and drive its output load accordingly. The reference voltage circuit (Fig. 2) includes three items: a switchable positive or negative voltage generator using one operational amplifier (OPAMP1); one non-inverting amplifier (OPAMP2); and one inverting amplifier (OPAMP3).