Switching power source circuitry having a current bypass circuit

Abstract

Power source circuitry is disclosed and has a DC power source and a switching circuit positioned at the primary side, a diode and a coil positioned at the secondary side and serially connected to a load, and a capacitor connected in parallel to the load. A current bypass circuit is connected in parallel to the load, and operates when a voltage applied to the load momentarily increases. When a current flowing through a load sharply decreases, the current bypass circuit conducts an abnormal current to be input to the load to the negative side. This suppresses the momentary increase in the voltage applied to the load. In a normal condition, no potential differences occur between the base and the emitter of a transistor, so that the transistor remains in an OFF state and prevents a current from flowing through the bypass circuit.

Dependencies are inferred from the claim text.