| 摘要 |
PROBLEM TO BE SOLVED: To provide a ringing choke type switching power supply apparatus in which a base current of a main switching element is automatically adjusted to an always suitable value, power supply efficiency is high and a circuit configuration is simple.SOLUTION: The switching power supply apparatus includes: a timer capacitor 50; a charging circuit 52 which generates current I52 according to a level of voltage Vij corresponding to input voltage Vi, and in an ON period of a main switching element 14, allows the current I52 to flow into the other end of the timer capacitor 50 through a voltage drop element 62; a reset circuit 54 for short-circuiting the timer capacitor 50 in an OFF period of the main switching element 14; a first diode 56 of which the anode is connected to a second terminal 26(2) of an auxiliary winding 12c; a first transistor 58 of which the collector is connected to a cathode of the first diode 56 and the base is connected to a middle point between the charging circuit 52 and the voltage drop element 62; and a first resistor 60 connected between an emitter of the first transistor 58 and a base of the main switching element 14. |
