Patent ID: 7263625

Claim:
A power supply controller which directs the supply of a plurality of different voltages from a power supply unit, comprising: a state register circuit to store state values corresponding to a combination of voltages supplied by the power supply unit; a reference clock oscillator circuit; a state value setting combination circuit which generates a change instruction to change the combination of voltages supplied by the power supply unit; a state value changing combination circuit which changes the state values one by one in a predetermined order corresponding to a target combination of voltages when the change instruction is received to change the combination of voltages supplied by the power supply unit; an output section to transmit the combination of voltages corresponding to the change instruction state values successively changed by said state value changing combination circuit to the power supply unit, wherein an information processor to which the plurality of voltages are supplied has a plurality of sections operating on the plurality of voltages; said state register circuit has state values of combinations of voltages respectively supplied to the plurality of sections; when said state value changing combination circuit receives the change instruction to change the combination of voltages supplied to the plurality of sections it changes the state values in a predetermined order indicating for which one of the sections the voltage should be changed first; said output section supplies the combinations of voltages corresponding to the state values changed one by one from the power supply unit to the sections of the information processor; wherein a predetermined combination of voltages provided to the sections of the information processor are supplied through one of a plurality of operating modes discriminated in power consumption in the information processor; and when the state value changing combination circuit receives an invalid change instruction corresponding to none of the plurality of operating modes, it sets the state values far supplying a combination of voltages representing the nearest corresponding valid operating mode.