US Patent No. 9,575,528

POWER SUPPLY VOLTAGE CONTROL SYSTEM


Patent No. 9,575,528
Issue Date February 21, 2017
Title Power Supply Voltage Control System
Inventorship Takeshi Aoyagi, Tokyo (JP)
Assignee CANON KABUSHIKI KAISHA, Tokyo (JP)

Claim of US Patent No. 9,575,528

1. A power supply voltage control system comprising:
a semiconductor integrated circuit; and
a power supply unit configured to supply a power supply voltage to the semiconductor integrated circuit,
the semiconductor integrated circuit including:
a data processing unit configured to operate in any of a plurality of operating states,
a storage unit configured to store information of a corrected voltage value required for the data processing unit to operate
in a predetermined operating state,

an interface unit configured to output, to the power supply unit, the information of the corrected voltage value stored in
the storage unit,

a clock supply unit configured to supply a clock signal having a first frequency and a clock signal having a second frequency
to the data processing unit, and

a calculation unit configured to calculate a time taken for an initial voltage value to reach the corrected voltage value
based on a difference between the initial voltage value and the corrected voltage value,

wherein the power supply unit supplies a voltage to the data processing unit based on the initial voltage value and the clock
supply unit supplies the clock signal having the first frequency to the data processing unit at startup of the semiconductor
integrated circuit,

wherein the interface unit outputs, to the power supply unit, the information of the corrected voltage value stored in the
storage unit in accordance with the voltage supplied to the data processing unit having reached the initial voltage value,

wherein the power supply unit supplies a voltage to the data processing unit based on the information of the corrected voltage
value output from the interface unit,

wherein the clock supply unit switches a clock signal to be supplied to the data processing unit from the clock signal having
the first frequency to the clock signal having the second frequency based on the initial voltage value and the corrected voltage
value, and

wherein the clock supply unit controls a timing at which the clock to be supplied to the data processing unit is switched
from the clock signal having the first frequency to the clock signal having the second frequency based on the calculated time.