Overload protection for electronically controlled circuit - employs sensor in parallel with power regulating element typically transistor and has two comparators in parallel

摘要

The overload protection circuit is typically applied to sub-circuits in motor vehicles, for example turn indicators, which are controlled electronically. The sensing circuit (6) is connected in parallel with the power regulating element (3), usually a transistor. By operating directly onto the power regulator the light current control circuit (5) is well protected against damage due to overload. The sensor normally contains at least one comparator (7) which checks the voltage across the transistor (3) against a reference level. If this level is passed, the comparator generated a signal to connect the transistor base to the emitter, thus stopping conduction.