| 摘要 |
PURPOSE:To apply a test pattern to all input pins of respective function blocks by providing a chip nonselection circuit which controls the output of an unselected function block to high impedance at the time of a test. CONSTITUTION:When a function block 1 is selected and tested, selector circuits 11, 12, 13, 41, 42, and 43 are controlled with a test mode signal to switch a normal signal N and a test signal input T to the function block 1. Further, inputs to input terminals S1 and S2 are passed through a decoder 32 to convert the input to the chip nonselection terminal CS' of the function block 1 to a high level and inputs to the chip nonselection terminals CS' of other function blocks 2 and 3 to a low level, thereby selecting the function block 1. Consequently, the input to a chip selection CS is not fixed and a test using the chip selection signal CS is enabled.
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