| 摘要 |
PURPOSE:To execute the functional test with fewer number of terminals by switching an input to an IC into a serial input to a shift register and reading the output serially after it is set once to the shift register. CONSTITUTION:External signal input terminals 21-25 and output terminals 31- 34 are opened, a signal to be applied to the terminals 25-21 is applied to a serial input terminal 19 and the shift register 50 is set. In bringing the level of a data selector control input terminal 37 to logical 1, the content of the register 50 is selected by a data selection section 70 and an output signal appears at the terminals 31-34. Then a signal on the terminals 31-34 is selected by a data selection section 80 and set to a shift register 60. A signal set to the register 60 is read serially from the output terminal 20 by bringing the level of the terminal 37 to logical 0. The functional test is conducted while performing the logical function of the IC without using the terminals 21-25 and 31-34. |
