A semiconductor integrated circuit device has a hierarchical power supply
system for a logic circuit. Inverters are provided with power supply from
a main power supply line and a sub-power supply line of a higher potential
and a main ground line and a sub-ground line of a lower potential. An
internal power supply voltage-down converter is placed to set the voltage
of the main power supply line higher than a normal operation voltage of
the higher potential. An internal supply voltage boosting circuit is
placed to set the voltage of the main ground line lower than a normal
operation voltage of the lower potential. When respective power supply
lines are short-circuited by a switching transistor, the voltage of each
power supply line can be maintained at an operation supply voltage.
