| 摘要 |
PROBLEM TO BE SOLVED: To reduce standby power while suppressing vibration noise in a transformer when a load is light in a normal mode.SOLUTION: A power supply device comprises: a transformer T1 that has a primary winding, a secondary winding, and an auxiliary winding; an FET1 for switching 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 CNT1 that controls switching operation of the FET1 according to the voltage output from the current detection resistor Ris; a Zener diode Dz1 that detects a voltage induced by a first auxiliary winding Nh having different winding direction from that of the primary winding of the transformer T1; and voltage dividing resistors Rz and R1 that correct the voltage output from the current detection resistor Ris to the control module CNT1 when the voltage induced by the first auxiliary winding Nh is higher than the Zener voltage of the Zener diode Dz1. |
