Overload current protection circuit for dc-dc converter

Abstract

Abstract PURPOSE: To protect a control transistor without using a fuse and a circuit breaker, by forming a circuit so that switching operation is stopped to make an output voltage zero when an overload current is detected. CONSTITUTION: The circuit comprises a resistor 7 connected in series with a load circuit, an overload current detection transistor 6 which acts in response to the rise in the terminal voltage of the resistor 7, a relay 11 which is energized by the turn-on of the transistor 6 so that the oscillation of a rectangular wave oscillator 2 is stopped and the relay 11 is kept energized by its contacts, delay circuits 9, 10 for delaying the starting of the energization of the relay behind that of the action of the transistor 6, and a switch 13 for de-energizing the relay. When the load current is below a rated value, the output voltage is kept constant by a voltage stabilization circuit 5. When the load current has exceeded the rated value, the output voltage and current are immediately made zero. COPYRIGHT: (C)1979,JPO&Japio

Inventors

• 👤 Yasuyoshi Nagao

Bibliographic Details