| 摘要 |
PROBLEM TO BE SOLVED: To reduce standby power that is power consumed in a light load state, while suppressing vibration sound of a transformer in a middle load state.SOLUTION: A power supply device comprises: a transformer T1 that has a primary winding, a secondary winding, and an auxiliary winding; an FET 1 that switches power to the primary winding of the transformer T1; a current detection resistor Ris that detects a current flowing in the primary winding, and outputs a voltage according to the current; a control module CNT 1 that controls switching operation of the FET 1 according to the voltage output from the current detection resistor Ris; a diode D1 and a capacitor C2 that rectify and smooth a voltage induced by a first auxiliary winding Nh having different winding direction from that of the primary winding of the transformer T1; a Zener diode Dz1 that detects a charging voltage of the capacitor C2; and resistors Rz and R1 that corrects the voltage output from the current detection resistor Ris to the control module CNT1 when the charging voltage is higher than the Zener voltage of the Zener diode Dz1. |
