| 摘要 |
PURPOSE:To decrease terminals for testing, by connecting a pull-up or pull-down element, which provides a signal line with a logically fixed constant potential, with a two-position controllable addition output circuit by means of an external signal. CONSTITUTION:In testing a division unit 30, the other units are disconnected from a signal line 40 while kept in high-resistance states, and in an output mode an output in an addition output circuit 60 is turned OFF by an input 70, and then the signal line 40 is pulled up to VDD so that its testing is performed at an terminal 90 through a selector 80. In testing the division unit 30 being in an input mode, an output circuit 20 is held in a high-resistance state, and an input signal is supplied from the terminal 70 via the addition output circuit 60. Normal operation, where the addition output circuit 60 is turned OFF by means of the terminal 70, causes no trouble. This composition enables the addition output circuit to be electrically disconnected, except when needed, without test terminals for high impedance control, decreasing pins in the testing device and realizing a decrease in cost.
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