| 摘要 |
PURPOSE:To add a test circuit automatically by replacing an existent pin with a two-way pin and utilizing it as test data input and output pins, and adding the test circuit. CONSTITUTION:When a test is conducted, the input test pin 4 and output test pin 5 are both held at '1' to place a two-way buffer 21 for test data input in an input mode and two-way buffer 22 for test data output in an output mode. Here, data inputted from the two-way pin 19 for test data input is inputted to the TD pin of a FF 23 through the buffer 21 and latched at the rise of the signal of a clock input pin 2, and the signal is further passed through a circuit 12 to be tested, latched by a FF 24 at the next rise of the input pin 2, and outputted from the TQ pin. Then the data is outputted from the two-way pin 20 for test data output through the buffer 22. Thus, the test circuit is added automatically.
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