Patent ID: 7376847

Claim:
In an integrated circuit, wherein power is supplied by different power supplies to different parts of the circuit, a control apparatus for providing each circuit part with a predetermined sequence during a power-up transition period, wherein at least one predetermined power-up sequence is related to stability of the power supplies during the power-up transition period, the apparatus comprising: at least one power switch, connecting each power supply to a corresponding circuit part; at least one power switch controller, regulating the at least one power switch; and a configuration wherein: inputs to the at least one power switch controller comprise a set of power outputs from all the power supplies that are considered in the power-up sequence of the corresponding circuit part; a regulating output of the at least one power switch controller is a function of the power outputs from all the power supplies that are considered in the power-up sequence of the corresponding circuit part; stability of input power levels is monitored by the at least one power switch controller to generate a regulating output that controls the at least one power switch or a self power down control circuitry which eliminates operational power after the power switch has reached a final regulating state, or both; and each power supply individually supplies power to the corresponding circuit part after the power-up transition period.