Patent ID: 6567252
Filing Date: 2003-05-20
Classification: H02H,H04N

Abstract:
Protection circuit for monitoring output voltages of a power supply unit comprisinga switching stage with a control input, to which at least two output voltages of said power supply unit are coupled, said output voltages being isolated from one another respectively by means of a diode and a resistor, a passive network for generating an operating voltage for said switching stage from a further output voltage of said power supply unit, said passive network providing said operating voltage for said switching stage with a delay, after switching on of said power supply unit, so that said control input is pulled up by the output voltages to be monitored before said operating voltage is present at said switching stage; in the event of a fault of one of said output voltages, in particular in case of a short-circuit, said switching stage providing an information signal for said power supply unit, so that said power supply unit switches off and reduces said output voltages as well as said operating voltage and herewith resetting said information signal, so that said power supply unit subsequently turns on and providing a cyclically switching on of said power supply unit as long as said fault exists.