Patent ID: 6781852
Filing Date: 2004-08-24
Classification: H02M,Y02B

Abstract:
A switching power supply, comprising:a transformer having a primary coil and a secondary coil; a switching circuit connected between an input terminal and the primary coil of the transformer; a rectifier connected to the secondary coil of the transformer; a control circuit controlling the switching circuit; and first and second operating voltage generating circuits each generating an operating voltage of the control circuit; a first operating voltage generated by the first operating voltage generating circuit and a second operating voltage generated by the second operating voltage generating circuit having different values from each other the first operating voltage generating circuit including a first zener diode which determines a value of the first operating voltage and the second operating voltage generating circuit includes a second zener diode which determines a value of the second operating voltage, a zener voltage of the first zener diode and a zener voltage of the second zener diode having different values from each other.