| 摘要 |
PROBLEM TO BE SOLVED: To downsize a switching regulator with a low noise operation while a good efficiency is maintained. SOLUTION: The switching regulator 12 controls an FET 4 to an on state to supply a current I2 based on a voltage induced in the secondary winding 2b of a transformer 2 to a capacitor 9, thereafter turns the FET 4 to an off state to convert the storage energy of a choke coil 7 to a current 13, discharges the current 13 to a capacitor 9 through an FET 8, and discharges the residual energy of the transformer 2 to the capacitor 9 via an auxiliary winding 2c. The regulator I2 controls the FET 8 so that after at least both the residual energies are completely discharged, the on-state is maintained for a predetermined time to discharge the current I5 in a reverses route to the current I3 from the capacitor 9, thereby turning the FET 8 to the off state, and controlling the FET 4 the on-state during supplying of the current I4 based on the storage energy of the coil 7 to the winding 3c via the diode 10.
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