| 摘要 |
PURPOSE:To turn off momentarily a power transistor even if the ON/OFF duty of the power transistor(TR) is smaller by inputting sufficient charge to a capacitor by a conductive signal from a pulse transformer. CONSTITUTION:When a current shown in the arrow is inputted to an input winding of the pulse transformer 11, a voltage is induced in an output winding and a base current IB shown in the arrow flows to the power TR14 via a resistor 13. When the input current to the transformer 11 is lost, a voltage of opposite polarity is induced in the output winding and a TR18 is biased forward and turned on. The charge in a capacitor 16 is discharged via the emitter/base of the TR14 and the TR18. Then, even if the ON/OFF duty of the power TR14 is smaller and the leading of the base current IB is deteriorated, sufficient charge is charged to the capacitor 16. Thus, the drawing current when the TR18 is turned on is not smaller and the TR14 is turned on momentarily. |
