| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device for controlling switching power supply, wherein soft start is accomplished and current loss due to a switching element can be reduced under lightload. SOLUTION: Under lightload, two reference voltages are switched and compared with an error voltage VEAO through a light load detection circuit 18, and one of the reference voltages is set a light load detection lower limit voltage for stopping the oscillations of the switching element 1. The other is a light load detection upper limit voltage for starting oscillation of the switching element 1. Thus, the switching element 1 is caused to oscillate intermittently. The actuation start voltage V c<SB>-</SB>on of a start/stop circuit 9 is set to a value higher than a supply voltage V c<SB>-</SB>cnt1 when the error voltage VEAO matches with the light-load detection lower limit voltage. Thus, the switching element 1 is prevented from starting oscillation, until the error voltage VEAO exceeds the light load detection upper limit voltage, after the supply voltage VCC reaches the actuation start voltage V c<SB>-</SB>on at start time. COPYRIGHT: (C)2004,JPO
|
