| 摘要 |
Provided is a resonant switching power supply device that can reduce a common mode noise as well as an increase in frequency when a load is light. A resonant switching power supply device 1 equipped with a PFM control circuit 10 to control a switching frequency in such a way that an output voltage is brought to a desired value includes: a resonant circuit where a primary winding N1 of a transformer T2, a current resonant capacitor Cri and a reactor Lr are connected in series; rectifying circuits D1, D2 and Co that are connected to secondary windings N2 and N3 of the transformer T2 and obtain the output voltage Vo; and an electrostatic shield plate S1 disposed between the primary winding N1 and secondary windings N2 and N3 of the transformer T2. The reactor Lr is connected to one terminal of the primary winding N1 of the transformer T2 and the current resonant capacitor Cri is connected to the other terminal of the primary winding N1 of the transformer T2; and the electrostatic shield plate S1 is connected to a terminal of the reactor Lr that is situated at the side opposite to where the primary winding N1 of the transformer T2 is connected. |
