| 摘要 |
PURPOSE:To reduce the switching loss by connecting a series circuit of a parallel connection unit of a diode and an inductance element and a capacitor between the drain and the source of a field effect transistor. CONSTITUTION:A switching power source is composed of a field effect transistor (FET)Q1, and a DC voltage V0 is output from output terminals 1, 2 through rectifying and smoothing circuits D1-D2, C1, L1 from the winding N2 of the transformer T1. In this case, a diode D2 provided between the drain and the source of the FETQ1, the diode D3 of the capacitor C2, and an inductance element L2 are provided in parallel. Thus, when the FETQ1 is turned from ON to OFF, since the diode D3 and the capacitor C2 become a low impedance circuit, the rise of the voltage Vds between the drain and the source is smoothed. When the FETQ1 is turned from OFF to ON, the discharge of the capacitor C2 is prevented by the element L2 to reduce the ON time loss. |
