SEMICONDUCTOR INTEGRATED DEVICE

PURPOSE:To always restrain a power consumption by a method wherein a paper-supply line of a circuit to be operated only at a test is installed separately from a power-supply line of a circuit to be operated at a usual operation and the power-supply line of the circuit to be operated only at the test is grounded and no electric current is fed at the usual operation. CONSTITUTION:A circuit to be operated only at a test is mounted in addition to a circuit to be operated at a usual operation; a power-supply line 12 of the circuit 16 to be operated only at the test is installed separately from a power- supply line 18 of the circuit 14 to be operated at the usual operation. A power supply is fed to both of the power-supply lines 12, 18 at the test, a test such as SCAM BIST or the like is conducted. At the usual operation, the power supply is fed to only the power-supply line 18 of the circuit 14 to be operated usually; the usual operation is executed. The power-supply line 12 of the circuit 16 to be used only at the test is grounded; no power supply is fed to the circuit 16 and the circuit is not operated. Thereby, the usual operation and the test operation can be executed separately; a power consumption can be restrained with a large-scale integrated circuit.