| 摘要 |
PURPOSE:To reduce the turn-off time of the switching Tr by applying the forward and backward biases through turn-off of the 1st and 2nd driving transistors Tr respectively. CONSTITUTION:The 1st and 2nd driving TrQa and Qb are turned on and off each for the period of ''H'' of control signal DS. And the collector current of TrQa features Ica, and thus the voltage indicated by the solid line arrows are induced to secondary winding S. At the same time, forward bias current IBF flows between the base and the emitter of switching TrQs, and then TrQs is turned on the give flowing to collector current Ics. On the other hand, TrQa and Qb are turned off and on each when signal DS features ''L''. And thus the collector current of TrQb features Icb, and thus the voltage indicated by the dotted line arrows are induced at winding S and in accordance with the peak current. And backward bias current IBR flows instantaneously in order to negate the storage carrier between the base and the emitter of TrQs. As a result, the turn-off time can be reduced for current Icb. |
