Patent ID: 7487370

Claim:
A semiconductor device comprising: a first power supply circuit which receives an external power supply voltage supplied, and outputs a first internal power supply voltage not higher than the external power supply voltage; a second power supply circuit which receives the external power supply voltage supplied, and outputs a second internal power supply voltage not higher than the external power supply voltage; a first system module which receives the first internal power supply voltage, and performs a predetermined operation; a second system module which receives the second internal power supply voltage, and outputs a processing speed control signal for requesting a processing speed to be realized by said first system module; a first performance monitor circuit which measures a processing speed of said first system module when the first internal power supply voltage is applied, and outputs a (1A)th control signal which requests to set the external power supply voltage at a (1A)th level, and a (2A)th control signal which requests said first power supply circuit to set the first internal power supply voltage at a (2A)th level, such that the measured processing speed is not lower than the processing speed requested by the processing speed control signal; a second performance monitor circuit which measures a processing speed of said second system module when the second internal power supply voltage is applied, and, on the basis of the measured processing speed, outputs a (1B)th control signal which requests to set the external power supply voltage at a (1B)th level, and a (2B)th control signal which requests said first power supply circuit to set the second internal power supply voltage at a (2B)th level; and a selector which receives the (1A)th and (2A)th control signals, selects one of the (1A)th and (2A)th control signals which requests a higher external power supply voltage, and outputs the selected control signal as a first control signal, wherein said first power supply circuit outputs the first internal power supply voltage having the (2A)th level on the basis of the (2A)th control signal applied thereto, and said second power supply circuit outputs the second internal power supply voltage having the (2B)th level on the basis of the (2B)th control signal applied thereto.