Microcomputer having reduced power consumption through impedance control and frequency reduction
First Claim
1. A microcomputer having a plurality of units including a central processing unit operating according to a system clock, the microcomputer comprising:
- a power input terminal for inputting electric power from outside of the microcomputer and for providing the electric power to the microcomputer;
pulse signal generating means for generating a plurality of pulse signals, each pulse signal having a different frequency;
means for generating a selection signal;
pulse signal selecting means for selecting a pulse signal from among the plurality of the pulse signals responsive to the selection signal inputted to the pulse signal selecting means and for outputting the selected pulse signal as the system clock; and
power source impedance controlling means for controlling an impedance between the power input terminal and the plurality of units of the microcomputer based on a frequency of the selected pulse signal and for providing the inputted electric power to the plurality of units of the microcomputer.
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Accused Products
Abstract
A microcomputer comprising a clock circuit which selects a pulse signal as a system clock of the microcomputer from among a plurality of pulse signals and a power source impedance controlling circuit which controls an impedance between a power input terminal and the units of the microcomputer based on the frequency of the pulse signal selected by the clock circuit to provide the electric power to the units of the microcomputer. The power source impedance controlling circuit controls the impedance such that the power source impedance is made lower as the frequency of the selected pulse signal is higher.
23 Citations
18 Claims
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1. A microcomputer having a plurality of units including a central processing unit operating according to a system clock, the microcomputer comprising:
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a power input terminal for inputting electric power from outside of the microcomputer and for providing the electric power to the microcomputer; pulse signal generating means for generating a plurality of pulse signals, each pulse signal having a different frequency; means for generating a selection signal; pulse signal selecting means for selecting a pulse signal from among the plurality of the pulse signals responsive to the selection signal inputted to the pulse signal selecting means and for outputting the selected pulse signal as the system clock; and power source impedance controlling means for controlling an impedance between the power input terminal and the plurality of units of the microcomputer based on a frequency of the selected pulse signal and for providing the inputted electric power to the plurality of units of the microcomputer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A microcomputer having a plurality of units including a central processing unit operating according to a system clock, the microcomputer comprising:
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a power input terminal for inputting electric power from outside of the microcomputer and for providing the electric power to the microcomputer; pulse signal generating means for generating a plurality of pulse signals, each pulse signal having a different frequency; means for generating a selection signal; pulse signal selecting means for selecting a pulse signal from among the plurality of the pulse signals responsive to the selection signal inputted to the pulse signal selecting means and for outputting the selected pulse signal as the system clock; power source impedance controlling means for controlling an impedance between the power input terminal and a first part of the plurality of units of the microcomputer based on a frequency of the selected pulse signal for providing the inputted electric power to the first part of the plurality of units of the microcomputer; and electric power providing means for providing a second part of the plurality of units of the microcomputer with the electric power inputted to the power input terminal. - View Dependent Claims (17, 18)
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Specification