LOGIC INPUT CIRCUIT ADAPTABLE IN FUNCTION OF INPUT VOLTAGE AND WITH A LOW THERMAL DISSIPATION

摘要

A logic input circuit for an industrial equipment automatic control system supplied by a DC voltage source, in particular a battery (16), comprises a voltage step-up energy converter (12) composed of an inductance coil (L) and a switching transistor (TR), connected to the input (E1) of the circuit (10); a logic level detector (DL) having a optocoupler; and a clock circuit (H) controlling the transistor (TR) by adjusting the frequency or the duty cycle to perform voltage matching with the signals applied to the input (E1), and also the value of the voltage surge generated in logic high state (1) by the inductance coil (L) when switching of the transistor (TR) to the off state takes place.