| 摘要 |
PURPOSE:To obtain an FET drive circuit with high efficiency, light weight and small size and mis-operation by connecting a 3-terminal switch element between a gate and source of the FET and discharging an electric charge stored in an input capacitor of the FET through the element. CONSTITUTION:When the switch element Q2 is turned on by a drive pulse from a signal source 1, a voltage produce in a winding N2 of a transformer T1 is applied between a gate G and a source S of an FETQ1 through a diode D3. As a result, a gate current flows and an input capacitor Cin is charged and the FET Q1 is turned on. When the element Q2 is turned off, a flyback voltage of the winding N2 is subject to discharge operation through a resistor R3 and a diode D2, a potential difference between a point B of the D3 and a point A of the D3 by the charged charge of the Cin is caused, a current flows to a bias circuit 3 by the potential difference and a 3-terminal switch element Q3 is conducted. The electric charge in the Cin is discharged through the element Q3 by the conduction. Thus, the switching speed is quickened and high efficiency is attained. |
