| 摘要 |
PURPOSE:To make it possible to protect an output circuit from an overcurrent by cutting off completely the output of a pulse circuit, composed of PNP and NPN transistors, on arrival of the overcurrent, by inpterposing a resistance between the output and load in series. CONSTITUTION:Between the output of PNP transistor Q1 and NPN transistor Q2 and smaple IC group 7, resistance R1 is connected interposing. If an overcurrent would flow to the output in a dynamic bias test by some reason, a voltage across voltage of resistance R1 is detected to let light emission diodes D1 and D2 come on and the light is detected by photo detection transistors T1 and T2; and their outputs are inputted to inhibit circuit 4 in the emitter-follower form and outputs SA and SB of it are inputted to gate circuits 2 and 3 to turn OFF transistors Q1 and Q2, so that the pulses will completely be cut off. Therefore, the pulse output circuit is protected from the overcurrent and the damage of transistors Q1 and Q2, and that caused by the heating of IC group 7 can both be prevented. |
