| 摘要 |
PROBLEM TO BE SOLVED: To resolve the problem that a response time from turning-on to turning-off is made long by a long transition time from turning-on to turning-off of a photo coupler and an influence of electric charges stored in a parasitic capacity between a base and an emitter of an output transistor, in an insulated contact output circuit which insulates an input digital signal by the photo coupler and controls a base current of the output transistor by the photo coupler to control turning-on/off of the photo coupler. SOLUTION: The input digital signal is inverted by an inverter, and an output of the inverter is inputted to a second photo coupler, and the base and the emitter of the output transistor are short-circuited by an output of the second photo coupler. Since the transition time from turning-off to turning-on of the photo coupler is much shorter than that from turning-on to turning-off, the base current of the output transistor is bypassed to the emitter by the second photo coupler, and electric charges stored in the parasitic capacity between the base and the emitter can be discharged, so that the response time from turning-on to turning-off of the output transistor can be shortened. COPYRIGHT: (C)2008,JPO&INPIT
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