Clock supply circuit
First Claim
1. A clock supply circuit for feeding a clock signal to a functional block of an electronic apparatus having a functional block being operating based on a clock signal produced by dividing a system clock comprising:
- a clock dividing section for generating said clock signal to be fed to said functional block by dividing said system clock; and
a control section for controlling a supply of said clock signal from said clock dividing section to said functional block depending on an active state of said functional block where a desired operation is required or on an idle state where no operation is required wherein said clock dividing section is adapted to generate a plurality of clock signals each having a different frequency and wherein said control section comprises selectors adapted to selectively output said plural clock signals fed by said clock dividing section, and a decision section adapted to control a selection operation of said selectors so that, in an active state of said functional block where said desired operation is required, a clock signal selected out of said plural clock signals having proper frequency is supplied to ensure adequate operations of said functional block and so that, in an idle state, a clock signal having a frequency being lower than that of said clock supplied in said state where said desired operation is required is fed to said functional block and wherein said electronic apparatus is equipped with a plurality of functional blocks and wherein said clock dividing section is adapted to generate a plurality of clock signals each having a different frequency and wherein each functional block is provided with one of the selectors for providing the selected frequency to the functional block.
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Accused Products
Abstract
A clock dividing section receives a system clock and generates and outputs clock signals of two or more types. Selectors select any of the clock signals of two or more types outputted by the clock dividing section and feed it to a printing control block or reading control block. A decision divider monitors operational states of each block and gives control so that a frequency to be supplied to a functional block in an idle state where any operation is not required is lower than that to be supplied to a functional block being in an active state. Power consumption of the whole custom IC can be more reduced compared with a configuration wherein a clock of fixed frequency is constantly supplied to each functional block and a noise can be controlled.
102 Citations
24 Claims
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1. A clock supply circuit for feeding a clock signal to a functional block of an electronic apparatus having a functional block being operating based on a clock signal produced by dividing a system clock comprising:
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a clock dividing section for generating said clock signal to be fed to said functional block by dividing said system clock; and
a control section for controlling a supply of said clock signal from said clock dividing section to said functional block depending on an active state of said functional block where a desired operation is required or on an idle state where no operation is required wherein said clock dividing section is adapted to generate a plurality of clock signals each having a different frequency and wherein said control section comprises selectors adapted to selectively output said plural clock signals fed by said clock dividing section, and a decision section adapted to control a selection operation of said selectors so that, in an active state of said functional block where said desired operation is required, a clock signal selected out of said plural clock signals having proper frequency is supplied to ensure adequate operations of said functional block and so that, in an idle state, a clock signal having a frequency being lower than that of said clock supplied in said state where said desired operation is required is fed to said functional block and wherein said electronic apparatus is equipped with a plurality of functional blocks and wherein said clock dividing section is adapted to generate a plurality of clock signals each having a different frequency and wherein each functional block is provided with one of the selectors for providing the selected frequency to the functional block. - View Dependent Claims (2, 3, 10, 11, 12)
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4. A clock supply circuit for feeding a clock signal to a functional block of an electronic apparatus having a functional block being operating based on a clock signal produced by dividing a system clock comprising:
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a clock dividing section for generating said clock signal to be fed to said functional block by dividing said system clock; and
a control section for controlling a supply of said clock signal from said clock dividing section to said functional block depending on an active state of said functional block where a desired operation is required or on an idle state where no operation is required wherein said electronic apparatus is provided with a first functional block to control reading of data and a second functional block to control printing operations, having a facsimile function and copying function and wherein said dividing section is adapted to generate a clock signal having three kinds of frequencies, i.e., lowest frequency, highest frequency and intermediate frequency to be fed to said first and second functional blocks and said clock signal to be fed to said functional block according to the active state and idle state of said each functional block is selected out of said clock signal having said lowest, highest and intermediate frequencies with reference to each of operational modes including copying, sending and receiving operation modes of said electronic apparatus. - View Dependent Claims (5, 6, 7, 8, 9)
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13. A clock supply circuit for supplying clock signals to an electronic apparatus having a plurality of functional blocks, each functional block operating based on said clock signal, comprising:
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a clock dividing section to receive and divide a system clock, and to output a plurality of clock signals with different frequencies;
a decision section for selecting one appropriate frequency from the plurality of clock signals to be supplied to one of the plurality of functional blocks based on an operating state signal of the one of said plurality of functional blocks and for outputting a decision signal as a frequency selection signal; and
at least one selector receiving at least two clock signals outputted from said dividing section and receiving said decision signal outputted from said decision section, selecting one of the received clock signals based on the received decision signal, and outputting said selected clock signal to said electronic apparatus for supplying said selected clock signal to said one of said functional blocks. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification