| 摘要 |
PURPOSE:To generate an input test pattern in a random mode and to test thereby function of an integrated circuit, by preventing the formation of a positive feedback circuit system ranging from an internal circuit to a reentry pin and back to the internal circuit. CONSTITUTION:When the logic function of an integrated circuit is tested, a test pattern generated in a random mode from an input terminal 2 is inputted. When a signal of ''0'' is supplied to an output control pin 9, a signal of ''0'' of ''1'' is given to an input-output switching pin 7, and thereby the output of the first AND gate circuit 11 and that of the second AND gate circuit 12 out of the outputs of an auxiliary gate 6 are made opposite to each other. Therefore, a signal current is checked by a NOR gate 3 and an AND gate 5, even when the test pattern in a random mode which is supplied to an internal circuit 1 is the one forming a positive feedback circuit through the intermediary of a reentry pin. |
