| 摘要 |
PROBLEM TO BE SOLVED: To draw electric charges, which are stored in the collector area of a transistor for driving, into a base area. SOLUTION: When the output of a driving circuit 33 becomes low level in the state of turning off a transistor T1 for driving, a transistor T2 for driving is turned off and a back electromotive force is generated from an induced load L1. A voltage at a point P shown in the figure is increased by the generated back electromotive force and the voltage at the point P becomes higher than the base terminal of the transistor T1 for driving. Then, a diode 11 is forward biased and the transistor T1 for driving is inversely turned on. When the output of the driving circuit 33 becomes high level, a P type MOS switch 12 is turned on and a potential at the base terminal of the transistor T1 for driving becomes lower than a potential at an emitter terminal by a negative voltage source V2. As a result, the electric charges in the collector area are drawn into the base terminal side and the transistor T1 for driving is turned off. Afterwards, the transistor T2 for driving is turned on. |
