# US 2014/0195840 A1 · Method for power management and an electronic system using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0195840 A1 - Document ID: US20140195840A1 - Status: Published application - Kind: A1 - Application number: 14/023,668 - Filed: 2013-09-11 - Published: 2014-07-10 - Earliest claimed: 2013-01-06 - Assignees: VIA Technologies, Inc. - Applicants: Via Technologies, Inc. - Inventors: Xiaolu YANG; Zongpu QI - Web page: https://patentgrep.com/patent/US20140195840A1 ## CPC - G06F 1/3228: Monitoring task completion, e.g. by use of idle timers, stop commands or wait commands - G06F 1/3237: by disabling clock generation or distribution - G06F 1/3296: by lowering the supply or operating voltage - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A power-management method is provided, and the power-management method includes setting a central processing unit in a first low-power state when receiving a second low-power state request requiring the central processing unit to enter the second low-power state, obtaining first idle periods of the peripheral modules respectively to determine a second idle period according to the first idle periods of the peripheral modules, determining whether the peripheral modules have not sent a data-access request during the second idle period, setting the central processing unit in the second low-power state when the peripheral modules have not sent the data-access request during the second idle period, wherein each first idle period is an interval period between two data transmissions of each peripheral module. ## Claims ### Claim 1 A power-management method for an electronic system, wherein the electronic system comprises a central processing unit and a plurality of peripheral modules, and the power state of the central processing unit includes a working state, a first low-power state and a second low-power state, wherein the power-management method comprises: setting the central processing unit in a first low-power state when receiving a request requiring the central processing unit to enter the second low-power state; obtaining first idle periods of the peripheral modules respectively; determining a second idle period according to the first idle periods of the peripheral modules; determining whether the peripheral modules have not sent a data-access request during the second idle period; and setting the central processing unit in the second low-power state when the peripheral modules have not sent the data-access request during the second idle period, wherein each first idle period is an interval period between two data transmissions of each peripheral module. ### Claim 2 (depends on 1) The method of claim 1, further comprising: maintaining the central processing unit in the first low-power state when one of the peripheral modules sends the data-access request during the second idle period; and after the peripheral module finishes the transmission of the data-access request, determining whether the peripheral modules have not sent a data-access request during the second idle period. ### Claim 3 (depends on 2) The method of claim 2, wherein after the peripheral module finishes the transmission of the data-access request, the counting of the second idle period is reset. ### Claim 4 (depends on 1) The method of claim 1, further comprising: estimating a prediction idle period of the electronic system; determining whether the prediction idle period minus the second idle period is longer than a target idle period; and when the prediction idle period minus the second idle period is not longer than the target idle period, maintaining the central processing unit being in the first low-power state. ### Claim 5 (depends on 4) The method of claim 4, further comprising: obtaining a plurality of history idle periods of the electronic system; and calculating the prediction idle period by a weighted averaging of the history idle periods. ### Claim 6 (depends on 1) The method of claim 1, wherein the request requiring the central processing unit to enter the second low-power state is issued by an operation system. ### Claim 7 (depends on 1) The method of claim 1, wherein the second idle period is set to the longest of the first idle periods of the peripheral modules. ### Claim 8 (depends on 1) The method of claim 1, wherein when the request requiring the central processing unit to enter the second low-power state is received, an idle reminder signal is further output to the peripheral modules; and the peripheral modules speed up data transmission when receiving the idle reminder signal. ### Claim 9 (depends on 1) The method of claim 1, wherein when the central processing unit is set to the second low-power state, a delay reminder signal is output to the peripheral modules; and the peripheral modules delay data transmission when receiving the delay reminder signal. ### Claim 10 (depends on 1) The method of claim 1, wherein the first low-power state is C2 state defined by the Advanced Configuration and Power Interface (ACPI), and the second low-power state is C3 state or C4 state defined by the Advanced Configuration and Power Interface (ACPI). ### Claim 11 An electronic system, comprising: a central processing unit, wherein the power state of the central processing unit includes a working state, a first low-power state and a second low-power state; a plurality of peripheral modules; an a power-management module, setting the central processing unit in a first low-power state when receiving a request requiring the central processing unit to enter the second low-power state, wherein the power-management module is configured to obtain first idle periods of the peripheral modules respectively, determine a second idle period according to the first idle periods of the peripheral modules, and determine whether the peripheral modules have not sent a data-access request during the second idle period; wherein when the peripheral modules have not sent the data-access request during the second idle period, the power-management module sets the central processing unit in the second low-power state; and wherein each first idle period is an interval period between two data transmissions of each peripheral module. ### Claim 12 (depends on 11) The electronic system of claim 11, wherein the power-management module maintains the central processing unit in the first low-power state when one of the peripheral modules sends the data-access request during the second idle period; and after the peripheral module finishes the transmission of the data-access request, the power-management module determines whether the peripheral modules have not sent a data-access request during the second idle period. ### Claim 13 (depends on 12) The electronic system of claim 12, wherein the power-management module further comprises an idle counter, the idle counter is configured to count the second idle period, and the power-management module resets the idle counter after the peripheral module finishes the transmission of the data-access request. ### Claim 14 (depends on 11) The electronic system of claim 11, wherein the power-management module further estimates a prediction idle period of the electronic system, and determines whether the prediction idle period minus the second idle period is longer than a target idle period; and wherein when the prediction idle period minus the second idle period is not longer than the target idle period, the power-management module maintains the central processing unit in the first low-power state. ### Claim 15 (depends on 14) The electronic system of claim 14, wherein the power-management module obtains a plurality of history idle periods of the electronic system, and calculates the prediction idle period by a weighted averaging of the history idle periods. ### Claim 16 (depends on 11) The electronic system of claim 11, wherein the request requiring the central processing unit to enter the second low-power state is issued by an operation system. ### Claim 17 (depends on 11) The electronic system of claim 11, wherein the second idle period is set to the longest of the first idle periods of the peripheral modules. ### Claim 18 (depends on 11) The electronic system of claim 11, wherein when the power-management module receives the request requiring the central processing unit to enter the second low-power state, the power-management module further outputs an idle reminder signal to the peripheral modules, and the peripheral modules speed up data transmission when receiving the idle reminder signal. ### Claim 19 (depends on 11) The electronic system of claim 11, wherein when the central processing unit is set to the second low-power state, the power-management module outputs a delay reminder signal to the peripheral modules, and the peripheral modules delay data transmission when receiving the delay reminder signal. ### Claim 20 (depends on 11) The electronic system of claim 11, wherein the first low-power state is C2 state defined by the Advanced Configuration and Power Interface (ACPI), and the second low-power state is C3 state or C4 state defined by the Advanced Configuration and Power Interface (ACPI).