Power supply device

摘要

The invention relates to a power supply device for a small-sized electronic appliance, and is intended to realize a reliable power supply device at low cost. <??>To achieve the object, a primary side coil (34) of a switching transformer and a switching element (35) are connected in series to both ends of an input power source (31), a series circuit of a resistance (32) and a capacitor (33) is connected to the input power source (31),the junction of the resistance (32) and capacitor (33) is connected to one end of a control winding (37) of the switching transformer, other end of the control winding (37) of the switching transformer is connected to a control terminal of the switching element (35), and a discharge circuit (40) driven by a signal of the control winding (37) of the switching transformer is used as means for discharging said capacitor (33), and therefore the conventional high withstand voltage diode is not necessary, reverse leak current is prevented, so that a highly reliable power supply device may be realized. <IMAGE>