| 摘要 |
PROBLEM TO BE SOLVED: To provide a tri-state CMOS output buffer that has an output node and a protection circuit for preventing an integrated circuit from being destroyed, when a bus voltage exceeds a power supply reference voltage. SOLUTION: A half bus circuit 224 of this output buffer blocks an output voltage passing through a final output stage, resulting in destruction of an output buffer 200, when an output voltage applied to an output node exceeds a supply vltage. A protection circuit employs a clamping circuit 210, a switching circuit 212, and a back gate bias circuit 206 to block a leakage path between a power supply reference voltage Vcc and an output node OUT passing through a source/bulk junction of a transistor that is biased in the output buffer.
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