DC-DC CONVERTER PROVIDED WITH OVERCURRENT PROTECTIVE CIRCUIT

摘要

PURPOSE: To provide a small-sized high-efficiency DC-DC converter with an improved overcurrent protective function. ;CONSTITUTION: At normal operation, if a switching transistor 3 is turned on by the control of the pulse width modulating circuit 4 of a converting CV, a transistor is turned on. When the transistor 3 is turned on, a transistor 10 is turned off, and a capacitor 13 charged during on is reversely charged by the electromotive force of an inductance 1. Hereby, the base current of the transistor 10 can be made intermittent without charging the capacitor 13 fully. If the voltage between the output terminals c and d drops by the short circuit of load, or the like, the reverse charge to the capacitor 13 by the inductance 1 decreases, consequently the capacitor 13 becomes fully charged by the base current of the transistor 10 and it breaks the base current. Therefore, the transistor 10 is turned off regardless of ON/OFF of the transistor 3, which breaks the power supply to the conversion part so as to protect the conversion part from an overcurrent.;COPYRIGHT: (C)1994,JPO&Japio