Patent ID: 7269780

Claim:
An integrated circuit device comprising: at least one functional module which has a plurality of flip-flops forming a scan chain, wherein the functional module performs a saving operation by outputting data in the flip-flops by a shift operation using the scan chain synchronized with a saving clock signal, and performs a restoring operation by restoring, to the flip-flops, the saved data by a second shift operation using the scan chain synchronized with a restoration clock signal; a power supply control unit which selects one of the functional modules, and controls stop and resumption of the power supply to the selected functional module; a clock signal generator which generates the saving clock signal and restoration clock signal for the functional module selected by the power supply control unit; a scan controller which, in the saving operation or restoring operation, sets the functional module selected by the power supply control unit to a scan test mode, and selects the saving clock signal or restoration clock signal generated by the clock signal generator as a clock signal to be supplied for the shift operation using scan chain; a shift register including a plurality of flip-flops wherein the shift register stores the save data output from the functional module selected by the power supply control unit by the shift operation using the scan chain synchronized with the saving clock signal; and an error checking and correction unit which performs error checking and correction for the save data stored in the shift register when the save data is to be restored to the flip-flops of the functional module by the second shift operation using the scan chain synchronized with the restoration clock signal, wherein the number of the second shift operations equals the number of the flip-flops of the functional moduule.