| 摘要 |
PURPOSE:To decrease power loss by providing a circuit not passing through the secondary winding of a drive transformer in the discharge path of an electric charge, and turning off the discharge circuit when the primary current flows to charge/discharge rapidly the switching element. CONSTITUTION:A rectangular wave signal is fed to a base B of a transistor (TR) 1 and a drive transformer DT is driven, then a gate of a switching TR 2 is charged forward via a resistor R2 and a diode D2 at the on-period of the TR1 to turn on the TR 2. Since a current flowing through a parallel circuit comprising a resistor R2, the TR2 and a resistor R3 flows to the diode D2, a base current of a TR 3 fed via a resistor R4 flows to a diode D3, does not turn on the TR 3 and the TR 2 keeps the on-state. When the TR 1 is turned off, the diodes D2, D3 are turned off by a flyback voltage of the transformer DT. The electric charge in the TR 2 flows via the resistor R4 as a base current of the TR 3, which is turned on, and the electric charge stored in the gate of the TR 2 is discharged rapidly. |
