Semiconductor integrated circuit and method for testing the same

A semiconductor integrated circuit comprising:

• a combinational circuit connected with a plurality of flip flop circuits;
• the plurality of flip flop circuits for capturing a plurality of output signals from the combinational circuit and for forming at least a scan chain;
• power source wiring for supplying power supply voltage to the plurality of flip flop circuits and the combinational circuit;
• and
• a variable power supply circuit for varying the power supply voltage to the power source wiring;
• wherein the variable power supply circuit supplies lower voltage to the combinational circuit during shift operation for scan testing than during capture operation.

A semiconductor integrated circuit comprising;

• a combinational circuit connected with a plurality of flip flop circuits;
• the plurality of flip flop circuits for capturing a plurality of output signals from the combinational circuit and for forming at least a scan chain;
• a flip-flop-circuit power source wiring for supplying first power supply voltage to the plurality of flip flop circuits;
• and
• a combinational-circuit power source wiring for supplying second power supply voltage to the combinational circuit,
• wherein the flip-flop-circuit power source wiring and the combinational-circuit power source wiring are electrically separate from each other and provide the first power supply voltage to the plurality of flip flop circuits and the second power supply voltage to the combinational circuit, respectively, and the first power supply voltage to the plurality of flip flop circuits and the second power supply voltage to the combinational circuit are independently adjustable.