Patent ID: 7830675

Claim:
A switching power supply device using a first power supply circuit for generating a first output power and a second power supply circuit for generating a second output power higher than the first output power, said device comprising: a switch circuit inserted between said first power supply circuit and said second power supply circuit and supplying/stopping, in response to a control signal, an electric power fed from said first power supply circuit to said second power supply circuit and required for starting said second power supply circuit; an operating/stop signal circuit for generating an operating signal or a stop signal; an external control circuit, responsive to the operating signal or the stop signal, for supplying the control signal to said switch circuit to turn on/off said switch circuit; a first detecting circuit for detecting the first output power of said first power supply circuit to produce a first output power detection signal; a first feedback circuit for feeding back the first output power detection signal as the first feedback signal to a primary-side circuit of said first power supply circuit; a second detecting circuit for detecting the second output power of said second power supply circuit to produce a second output power detected signal; a second feedback circuit for feeding back the second output power detection signal as the second feed back signal to a primary-side circuit of said second power supply circuit; and detecting means for detecting at least one of the first and the second feedback signals to deliver a detected signal to said external control circuit.