A semiconductor integrated circuit comprises a power supply voltage step down
circuit
and a MOS circuit group. The power supply voltage step down circuit is supplied
with a power supply voltage and controlled by a standby control signal indicating
an operating state or a standby state. The power supply voltage step down circuit
outputs a first internal power supply voltage lower than the power supply voltage
to an internal power supply line when the standby control signal indicates the
operating state, and outputs a second internal power supply voltage lower than
the first internal power supply voltage to the internal power supply line when
the standby control signal indicates the standby state. The MOS circuit group including
one or more MOS transistors which are supplied with the first or second internal
power supply voltage from the internal power supply line to operate.