Passive isolator circuit for DC signals transmission, uses input-side voltage monitoring circuit with reference voltage comparator and switching device for input overvoltages

摘要

A passive isolator has a input (IN+,IN-), and an output (OUT1+, OUT1-). An input-side converter circuit (W) converts the DC input signal into an AC signal. Also included are an auxiliary transformer (TR2) and an output-side rectifying circuit (C6,C7, D2), An input-side monitoring circuit (M) is provided for the input voltage and comprises a reference voltage comparator (R3,R4,R5,D4,IC1); a switching device (transistor) (T3) driven by the reference voltage comparator enables the latter when the reference voltage at the input (IN1+,IN-) is exceeded.