| 摘要 |
A semiconductor integrated circuit protected against a high voltage testing signal is provided. The integrated circuit includes a first-stage input circuit, a discriminating circuit, a power suppuly circuit and a connecting circuit. The input ends of the-input circuit and the discriminating circuit are connected to one preselected external terminal. The discriminating circuit renders a testing circuit drive signal active to activate when a testing instruction signal higher than an ordinary input signal voltage is applied to the external terminal. When the testing circuit drive signal is active, the power supply circuit disconnects at least one of the positive and negative poles of the power source having polarity opposite to that of the testing instruction signal from the input circuit, and the connecting circuit connects one of the positive and negative poles of the power source having the same polarity as that of the testing instruction signal to the output end of the input circuit.
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