| 摘要 |
PURPOSE:To prevent the element destruction due to the short-circuit accident of the output stage with a simple circuit constitution, by driving the transistor of the output short-circuit protecting circuit directly by the output of the current switch. CONSTITUTION:When input VIN of the current mode logic CML mode becomes H, transistor T1 is turned on, and output VOUT of transistor logic TTL becomes H. Therefore, voltage VX of the voltage division ratio of bias circuit 4 is applied to the base of transistor T4. Meanwhile, when output terminal 2 is short-circuited to earth potential GND, the controller current of transistor T4 is supplied through the path of power source +VCC-resistance R1-transistor T4, and the base current of transistor T3 is reduced rapidly and cannot hold the turn-on state. As a result, transistor T3 is prevented from being destructed thermally. |
