Controller

Abstract

The disclosed invention provides a controller that can prevent overshoot and undershoot from occurring when a voltage is switched to another voltage without using two types of regulators. Voltage regulators supply a power supply voltage to a CPU. An SVID interface receives a command to change the number of voltage regulators to be actuated among the voltage regulators from outside. A phase clock generating circuit makes a stepwise change of the number of voltage regulators to be actuated from the current number of regulators to the commanded number of regulators after change.

What is claimed is: 
     
         1 . A method of controlling a semiconductor system configured to supply power to a semiconductor device, the method comprising the steps of:
 activating a plurality of voltage regulators;   after the step (a), receiving a command from a semiconductor device, the command indicating a first number of voltage regulators to be activated;   after the step (b), deactivating an voltage regulator in the plurality of voltage regulators; and   after the step (c), deactivating another voltage regulator in the plurality of voltage regulators;
 wherein, after the step (d), the first number of voltage regulators are activated. 
   
     
     
         2 . A method of controlling a semiconductor system according to  claim 1 ,
 wherein the semiconductor device comprises a central processing unit.   
     
     
         3 . A method of controlling a semiconductor system according to  claim 2 ,
 wherein, after the step (c), a second number of voltage generators is activated;   wherein the second number is greater than the first number.   
     
     
         4 . A method of controlling a semiconductor system according to  claim 3 ,
 wherein the semiconductor system further comprising a register,   wherein the register configured to register a value indicating the second number,   wherein each of the step(c) and the step(d) is executed in accordance with the value stored in the register.   
     
     
         5 . A method of controlling a semiconductor system configured to supply power to a semiconductor device, the method comprising the steps of:
 supplying power to the semiconductor device by a first number of voltage regulators;   after the step(a), receiving a command from a semiconductor device, the command indicating a second number of voltage regulators to be activated;   after the step(b), supplying power to the semiconductor device by a third number of voltage regulators;   after the step(c), supplying power to the semiconductor device by the second number of voltage regulators,   wherein the first number is greater than the second number and the third number, and   wherein the third number is greater than the second number.   
     
     
         6 . A method of controlling a semiconductor system according to  claim 5 ,
 wherein the semiconductor device comprises a central processing unit.   
     
     
         7 . A method of controlling a semiconductor system according to  claim 6 ,
 wherein a value indicating the third number is stored in a register in the semiconductor system.