| 摘要 |
PROBLEM TO BE SOLVED: To provide a control circuit for a switching power supply wherein no excessive current flows to a main switch element even if an output transformer is saturated in regenerative operation. SOLUTION: The control circuit comprises a main switch element 4 for turning on/off a DC input power, a control part 2 which is connected to the main switch element 4 and controls on/off of the main switch element 4, and a main transformer 3. A sub-winding 3c is provided on the main transformer 3, and an auxiliary control circuit 26 controls the input voltage of a control input terminal 2a of the control part 2 in which the feedback signal of an output voltage is inputted to a low state until a specified time period passes after the voltage of the sub-winding 3c drops due to regenerative operation. The control part 2 does not apply a voltage to the gate of the main switch element 4 until a specified time period passes after the drain current of the main switch element 4 returns to zero if the main switch element 4 turns on while the gate voltage of the main switch element 4 is low due to the regenerative operation. COPYRIGHT: (C)2005,JPO&NCIPI
|
