| 摘要 |
PURPOSE:To protect the output transistor against the short-circuit or the like of a load, by providing a switching element, which becomes conductive when an excessive current is flowed to the output transistor, between the base and the emitter of the output transistor. CONSTITUTION:The collector of an open collector output transistor TR Q11 is connected to an output terminal T11 through a current detecting resistance R11, and a protecting TR Q12 is connected between the base and the emitter of the TR Q11. When the output TR Q11 becomes conductive by an output QA of a latch circuit, a current is supplied to a load from an external power source VS2. If an output current I0 becomes excessive to raise an output voltage V0 short-circuited, the TR Q12 becomes conductive to turn off the TR Q11. The TR Q12 is held in (a) conduction state and is reset by the conduction of a TR Q13 due to a clock pulse. |
