| 摘要 |
PURPOSE:To cope with a wide requested specification by constituting an output buffer circuit with at least a tri-state circuit or an open collector circuit and controlling the circuit from the outside of a semiconductor integrated circuit device. CONSTITUTION:The level of a tri-state selection terminal 24 is kept to a high level and a high impedance control circuit is kept to the high level, then the level of an output terminal 36 is decided definitely depending on the voltage level of an input terminal 25 and the circuit is actuated as a totem pole circuit. In bringing the level of the high impedance control terminal 27 to a low level from this state, transistors 33, 34 are both cut off and the output terminal 36 is kept to a high impedance. This shows that the circuit acts like a tri-state circuit. In keeping next a tri-state selection terminal 24 to a low level, the high impedance control terminal 27 is made effective and the high level output transistor 33 is cut off, then the circuit acts like an open collector circuit. |
