| 摘要 |
PURPOSE:To easily detect the improper connection of a terminating resistor on a high density mounting substrate by connecting a pull-up resistor between the high potential point of a logic output and the emitter terminal of an emitter follower transistor Tr. CONSTITUTION:When a transmission line 300 falls into a non-bias state due to the improper connection of a terminating resistor 400, the potential of the output terminal 501 of a semiconductor integrated circuit 500 becomes a level determined by the resistance ratio of a pull-up resistor 221 to the input resistance of a circuit 550 as observed from the input terminal 551 of a semiconductor integrated circuit 550. That is, since the resistor 221 here is set to a sufficiently smaller resistance value than the input resistance of the circuit 550, the terminal 501 is raised to the vicinity of a ground level. Thus, an emitter follower Tr 212 is cut OFF, and the terminal 501 is secured to a high level irrespective of the signal applied to the input terminal 202. Thus, since the improper connection of the resistor 400 is reflected in the logical operation, this improper connection can be easily detected.
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