| 摘要 |
A semiconductor circuit for compressing or encoding output data of a scan path circuit, able to realize a circuit test and fault analysis by the scan path circuit, and capable of preventing the configuration of a combinational circuit from being guessed from the input and output. Predetermined mode key data is input by being mixed in input data to a scan path circuit during a scan mode operation so as to be fetched by a mode key circuit embedded in the scan path circuit. The mode key data is fetched by the mode holding circuit from the mode key circuit and a mode signal BE is generated in accordance with the mode key data during a system mode operation. When the mode key data has a predetermined pattern, the mode key signal becomes a predetermined set value, and an output signal of the scan path circuit is output as it is in accordance therewith. Otherwise, since the output signal of the scan path circuit is encoded and output, the output of the scan path circuit can be concealed in accordance with need. |
