Signal level transforming circuit

摘要

A signal level transforming circuit includes a constant current circuit for supplying a constant current corresponding to a power voltage of an input signal to an electrical line connected between an output terminal connected with an input terminal via an input resistor and a common voltage level terminal, a low level clamping circuit for clamping the minimum value of the voltage at the output terminal to a first low level voltage, a voltage generating circuit for generating a constant voltage so as to transform a voltage signal in the input terminal into a binary signal, and a comparing circuit having a hysteresis characteristic and including a multi-collector type transistor having one collector connected with a voltage output terminal in the voltage generating circuit via a resistor for setting a comparing voltage, and having another collector connected to the output terminal, and a transistor inserted between a base of the multi-collector type transistor and the resistor for setting a comparing voltage and for turning ON when the voltage at the input terminal exceeds the voltage in the resistor.