| 摘要 |
PURPOSE:To achieve a test utilizing a test pattern of an existing chip as intact, by connecting an input or an output of the chip composing a composite chip to an external terminal before a test is carried out. CONSTITUTION:In the normal operation mode, an input signal of a normal operation mode/test mode switching terminal T1 is set to '1'. A selector circuit 6 outputs an output signal S2 of an additional circuit 7 to a (g) input to permit operation as composite chip. On the other hand, in the test mode, the input signal of the switching terminal T1 is set to '0'. The selector circuit 6 connects the (g) input of the existing chip to an external terminal X5 to permit the testing of the existing chip by inputting a test pattern of the existing chip from the external terminal X5.
|
