| 摘要 |
PROBLEM TO BE SOLVED: To prevent the floating of the low level of data signals due to a ground offset at the time of connecting plural semiconductor integrated circuits provided with a back flow prevention means between a ground line and an external terminal for exterior pull-down resistor connection to common bus wiring. SOLUTION: For this semiconductor integrated circuit, a back flow prevention circuit 3A is constituted of an nMOS transistor Q2A for which a source electrode and a back gate electrode are connected and both connected to a pull- down terminal 8A, a drain electrode is connected to the ground line 6A and the source electrode and a gate electrode are connected through a resistor R2A, a pMOS transistor Q1A connected so as to form a current route between a power source line 5A and the gate electrode of the nMOS transistor Q2A and a comparator 4A for judging the height of the potential of a bus terminal 7A with the potential of the ground line 6A as a comparison reference, converting a judged result to an inverted binary signal and inputting it to the gate electrode of the pMOS transistor Q1A.
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