US Patent 7696813 Semiconductor integrated circuit device

A semiconductor integrated circuit device for fast and low power operations, comprising a plurality of circuit blocks of a chip, each of which has a plurality of states with different power consumption values. A power management circuit determines the state of each of the circuit blocks so as not to exceed a maximum power consumption value of the semiconductor integrated circuit device by considering the power consumption of each circuit block and by each state transition in each circuit block. The maximum power consumption value may be preset or adjustable after fabrication.