| 摘要 |
PURPOSE:To make a DC check easily with a small number of test pins by providing a logical setting circuit in front of the final-stage output buffer circuit of an LSI, and using input pins as pseudo test pins. CONSTITUTION:The output of a gate circuit 21 which supplies a final output to a pin 26 of the LSI is supplied to the pin 26 through NAND circuits 22 and 23 constituting the test circuit and a buffer circuit 25. When the DC check is made, a test pin B and an input pin A1 are set at a level L, and an input pin A2 is switched to a level L or H; the output of the buffer circuit 25 is then switched to the level L or H forcibly to make the DC level check. When an action check is made, on the other hand, the test pin B is set to the level H, and then input signals from the input pins A1 and A2 become irrelevant to a forcible operating circuit 24, so that a pattern signal is inputted even from the input pins A1 and A2. |
