| 摘要 |
PCT No. PCT/JP93/01557 Sec. 371 Date Jun. 23, 1994 Sec. 102(e) Date Jun. 23, 1994 PCT Filed Oct. 28, 1993 PCT Pub. No. WO94/10705 PCT Pub. Date May 11, 1994.In an input/output protection circuit, since the drain of an input protection MOS transistor is directly connected to the cathode of input protection diode and the source and gate of the input protection MOS transistor and the anode of the input protection diode are respectively grounded, an excessive voltage supplied from an external electrode is received by the cathode of the input protection diode and the drain of the input protection MOS transistor before it reaches the internal circuit of a semiconductor device, so that the input/output protection circuit is free from the increase of junction capacitance due to the pattern of the input protection diode. Moreover, when an excessive voltage is input to the device, the input protection diode breaks down prior thereto so as to reduce the voltage at which the input protection MOS transistor starts to conduct. As a result, a high-speed and certain input protection is realized. Furthermore, since the input electrode can be directly connected to the drain of the input protection MOS transistor, the input protection circuit in FIG. 1 is applicable to an output protection circuit so as to certainly protect the internal output circuit by applying the input protection circuit to an output MOS transistor.
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