Variable-frequency sampling of battery voltage to determine fuel gauge power mode

A system for conserving power in an electronic device, in some embodiments, comprises: a battery to supply power to the electronic device; and a fuel gauge coupled to the battery and capable of operating in any of a plurality of power modes, wherein the fuel gauge selects its own power mode based on a repeated, variable-frequency sampling of a voltage provided by said battery.

BACKGROUND

Consumer electronics—such as smart phones, laptops, tablets, video cameras and handheld game consoles—are typically powered by batteries. Although such batteries are generally rechargeable, minimizing battery consumption has long been a primary design goal for such products. Extended battery life prolongs the amount of time between recharging sessions, thus delivering a significantly enhanced user experience.

SUMMARY

At least some of the embodiments disclosed herein are directed to a system for conserving power in an electronic device, comprising: a battery to supply power to the electronic device; and a fuel gauge coupled to the battery and capable of operating in any of a plurality of power modes, wherein the fuel gauge selects its own power mode based on a repeated, variable-frequency sampling of a voltage provided by said battery. At least some of these embodiments may be supplemented using one or more of the following concepts, in any order or combination: wherein the fuel gauge repeatedly samples said voltage at a sampling frequency corresponding to a currently-enabled power mode of the fuel gauge; wherein the power mode is selected from at least two different power modes, and wherein a higher one of said at least two different power modes is associated with more frequent sampling of said voltage by the fuel gauge, and wherein a lower one of said at least two different power modes is associated with less frequent sampling of said voltage by the fuel gauge; wherein said power mode is selected from the group consisting of: a stand by mode, a relax mode, an operation mode and an active mode; wherein the fuel gauge switches to a higher power mode than its currently-enabled power mode if said repeated sampling demonstrates a change in said voltage that meets or exceeds a voltage change threshold; wherein the fuel gauge maintains its currently-enabled power mode if said repeated sampling demonstrates a change in said voltage that fails to meet or exceed a voltage change threshold; wherein the fuel gauge switches to a lower power mode than its currently-enabled power mode if said repeated sampling demonstrates no change in said voltage; wherein the electronic device is selected from the group consisting of: a smart phone, a tablet, a laptop, a digital camera, and a handheld game console; wherein the fuel gauge selects its power mode based on four consecutive samples of said voltage.

At least some embodiments are directed to an electronic device, comprising: a battery that powers at least part of the electronic device; and a fuel gauge, coupled to the battery, that autonomously selects a power mode in which to operate based on a sampling of a voltage provided by said battery, wherein the fuel gauge selects said power mode based on a degree to which said voltage swings between samples and based on how often said voltage changes. At least some of these embodiments may be supplemented with one or more of the following concepts, in any order and in any combination: wherein, while operating within a single fuel gauge power mode, the fuel gauge varies a sampling frequency at which the fuel gauge samples said voltage; further comprising a programmable register that stores a voltage change threshold against which the fuel gauge compares said degree to which the voltage swings between samples and that stores a rate of change threshold against which the fuel gauge compares how often said voltage changes, and wherein the fuel gauge uses said comparisons to select said power mode; wherein a sampling frequency at which the fuel gauge samples said voltage is based on a currently-enabled power mode of the fuel gauge; wherein, if the fuel gauge determines that said voltage does not change over a predetermined number of consecutive samples, the fuel gauge switches to a lower power mode than its currently-enabled power mode; wherein, if the greatest battery voltage swing over a predetermined number of consecutive voltage samples is less than a voltage change threshold, or if the number of times that the battery voltage changes over said predetermined number of consecutive voltage samples is less than a rate of change threshold, the fuel gauge maintains its currently-enabled power mode; wherein, if the greatest battery voltage swing over a predetermined number of consecutive voltage samples is equal to or greater than a voltage change threshold, and if the number of times that the battery voltage changes over said predetermined number of consecutive voltage samples is equal to or greater than a rate of change threshold, the fuel gauge switches to a higher power mode than its currently-enabled power mode.

At least some embodiments are directed to a method for conserving power, comprising: repeatedly sampling a voltage provided by a battery housed within an electronic device; and selecting a fuel gauge power mode based on said repeated sampling, wherein said repeated sampling is performed at a variable sampling frequency that depends on a currently-enabled power mode of the fuel gauge, wherein said selecting is performed by the fuel gauge. At least some of these embodiments may be supplemented by one or more of the following concepts, in any order and in any combination: wherein said fuel gauge power mode is selected from the group consisting of: a standby mode, a relaxed mode, an operation mode, and an active mode; wherein the fuel gauge samples said voltage at a first sampling frequency during the relaxed mode, at a second sampling frequency during the operation mode, and at a third sampling frequency during the active mode, and wherein the second sampling frequency is greater than the first sampling frequency but less than the third sampling frequency; further comprising varying the sampling frequency while operating within a single fuel gauge power mode.

DETAILED DESCRIPTION

Disclosed herein are methods and systems for variable-frequency sampling of an electronic device battery voltage to determine a fuel gauge power mode. An illustrative electronic device implementing the techniques disclosed herein contains a battery supplying power to the components of the electronic device and a fuel gauge that monitors the battery. The fuel gauge is capable of operating in numerous power modes (e.g., standby mode, relaxed mode, operating mode, active mode), each one of which causes the fuel gauge to consume different amounts of power. The fuel gauge selects its power mode based on a sampling of the voltage provided by the battery. The fuel gauge samples this voltage at a variable frequency, with the precise frequency depending on the power mode in which the fuel gauge is currently operating and changing as the fuel gauge power mode changes. Based on the voltage swings between samples and on how often the voltage changes, the fuel gauge either switches to a lower power mode, stays in its currently-enabled power mode, or switches to a higher power mode.

For example, while the fuel gauge is in a standby mode, it may sample the battery voltage once per minute; in a relaxed mode, once every 20 seconds; in an operating mode, once every 10 seconds; and in an active mode, four times per second. If, while in any of these power modes, the fuel gauge consecutively samples the battery voltage a predetermined number of times and determines that there is no voltage change, the fuel gauge autonomously switches to a lower power mode (unless the fuel gauge is already in the lowest available power mode, such as a standby mode). If the fuel gauge consecutively samples the battery voltage the predetermined number of times and determines that there is at least one voltage change but that the greatest voltage change (in either direction) fails to meet or exceed a voltage change threshold, the fuel gauge remains in its currently-enabled power mode. Similarly, if the fuel gauge consecutively samples the battery voltage the predetermined number of times and determines that there is a threshold-exceeding voltage change but that the battery voltage does not change often enough to meet or exceed a rate of change threshold, the fuel gauge remains in its currently-enabled power mode. Finally, if the fuel gauge determines that there is at least one voltage change and that the greatest of these voltage changes meets or exceeds the voltage change threshold, and further if the fuel gauge determines that the battery voltage changes often enough to meet or exceed a rate of change threshold, the fuel gauge switches to a higher power mode (unless the fuel gauge is already in the highest available power mode, such as an active mode). Numerous variations and permutations of this technique are contemplated and included within the scope of the disclosure.

In some embodiments, the sampling frequency may vary even within the same fuel gauge power mode. For example, referring again to the foregoing example, if the fuel gauge determines that there is an increase in voltage variation (i.e., greater voltage swings between samples and/or a greater percentage of samples indicating voltage changes), but the voltage variation is not significant enough to warrant switching modes, the fuel gauge may remain in its currently-enabled power mode but it may increase or decrease its sampling frequency to account for the increased variation in battery voltage.

FIG. 1is a front view of an illustrative consumer electronic device100that implements the systems and methods described herein. The electronic device100may be any suitable device that uses a battery (e.g., a lithium ion battery). Non-limiting examples of such electronic devices include smart phones (e.g., APPLE iPHONE®, SAMSUNG GALAXY NOTE®), tablets (e.g., APPLE iPAD®, AMAZON KINDLE®), laptops, video cameras (including camcorders), and handheld game consoles (e.g., SONY PLAYSTATION VITA®). Other such devices are contemplated and included within the scope of this disclosure. The illustrative consumer electronic device100includes a display screen102that is preferably a touch screen. It further includes various tactile input devices104, such as buttons arranged in various locations around the exterior of the electronic device100. Additional input and output devices, such as microphones and speakers, also may be incorporated within such a device.

FIG. 2is a block diagram of components within the illustrative consumer electronic device100. The electronic device100includes an application-specific integrated circuit (ASIC)200comprising processing logic202(e.g., a microprocessor), storage206coupled to the processing logic202and comprising software code204(e.g., an operating system or applications), input features208(e.g., buttons, touch screen, microphone), output features210(e.g., display screen that may be the same as the touch screen, speaker, haptic feedback motor), and a network interface212for communicating with other devices (e.g., via the Internet). Other components may be included on the ASIC200. The ASIC200is powered by a battery pack (“battery”)214. A fuel gauge216couples to the battery214. In at least some embodiments, the ASIC200, the fuel gauge216and the battery214couple to each other in a parallel configuration, so that the ASIC200may receive power from the battery214while the fuel gauge216monitors the output of the battery214. Further, in some embodiments the ASIC200may be replaced by a plurality of ASICs or other circuitry. The techniques disclosed herein may be implemented in any electronic device in which any suitable type of load (here, the ASIC200) is powered by the battery214. In operation, and as described in greater detail with respect toFIG. 3, the fuel gauge216monitors the voltage output by the battery214. As explained above, the fuel gauge216autonomously selects its own power mode based on the battery voltage fluctuation—that is, based on the battery voltage swings between samples as well as the frequency with which the battery voltage changes.

FIG. 3is a block diagram of components within the consumer electronic device100and, more particularly, within the fuel gauge216. The block diagram ofFIG. 3is conceptual in nature, meaning that at least some of the blocks represent functions performed by the various parts of the electronic device100. The actual circuit logic used to implement the functions represented by the blocks may vary depending on design considerations and preferences and will be readily known to or determined by one of ordinary skill in the art.

Referring toFIG. 3, the battery214contains a voltage source300that creates a potential across terminals302,304. The terminal302provides a voltage to node318, which couples to the fuel gauge216and to the ASIC200. The terminal304couples to ground and to node320, which couples to the fuel gauge216and the ASIC200. The fuel gauge216comprises voltage detection logic306, a programmable voltage fluctuation level register308, mode control logic310, a clock312and port314, and a sampling timer316. The programmable register308contains the voltage change threshold value and the rate of change threshold value, described above. In operation, the voltage detection logic306samples the voltage present at node318(i.e., the battery voltage) at a sampling frequency that varies according to the currently-enabled mode of the fuel gauge216. In at least some embodiments, when the fuel gauge216is in a standby mode, the voltage detection logic306may sample the battery voltage once per minute; in a relaxed mode, once every 20 seconds; in an operating mode, once every 10 seconds; and in an active mode, four times per second, although the scope of disclosure is not limited to these sampling frequencies for each power mode, nor is the scope of disclosure limited to the use of a single sampling frequency in individual power modes.

If, upon consecutively sampling the voltage a predetermined number of times, the logic306determines that the voltage has not changed at all, the fuel gauge216switches to a lower power mode. If the logic306determines that the voltage has changed, but not by the voltage change threshold stored in the register308, or if the logic306determines that the voltage has changed by the voltage change threshold but that the voltage has not changed as often as required by the rate of change threshold, the logic306concludes that there is not enough variation in the battery voltage to warrant an upward power mode switch, and it remains in its currently-enabled power mode. If, however, the logic306determines that the battery voltage has changed by the voltage change threshold, and if the logic306further determines that the voltage has changed often enough (by any suitable amount, or by some additional minimum threshold programmed into the register308) to meet or exceed the rate of change threshold, the logic306issues a signal to the mode control logic310to increase the power mode of the fuel gauge216.

FIG. 4is a graph400illustrating a variable frequency voltage sampling scheme. The graph400plots different power modes on the x-axis402and power level on the y-axis404. Specifically, graph400shows a standby mode406, a relaxed mode408, an operation mode410, and an active mode412. During the standby mode406, the power level414is relatively low; during the relaxed mode408, the power level416is increased; during the operation mode410, the power level418is further increased; and during the active mode412, the power level420is highest. The sampling frequency at which the fuel gauge samples the battery voltage varies among these power modes. During standby mode406, numeral422indicates a relatively low sampling frequency; during relaxed mode408, numeral424indicates an increased sampling frequency; during the operation mode410, the sampling frequency426is further increased; and during the active mode412, the sampling frequency428is relatively high. Specific, illustrative sampling frequencies are provided above and thus are not reproduced here.

FIG. 5is a flow diagram of an illustrative method500usable to implement the techniques disclosed herein. The method500begins by determining a current fuel gauge power mode (step502). The method500includes performing a sampling operation in the current power mode (step504). A sampling operation is a sampling of the battery voltage a predetermined number of times at a predetermined sampling frequency, where the sampling frequency is determined based at least on the current power mode of the fuel gauge. The method500then includes determining whether the results of the sampling operation met the criteria for increasing the fuel gauge power mode (step506). If so, the fuel gauge autonomously increases its power mode (step508). Otherwise, the method500comprises determining whether the results of the sampling operation met the criteria for decreasing the fuel gauge power mode (step510). If so, the fuel gauge autonomously decreases its power mode (step512). Otherwise, the currently-enabled power mode is maintained. Control of the method500then returns to step504, as is the case after completion of steps508and512. The method500may be modified as desired—for example, to include additional steps, delete steps, or rearrange steps.

Numerous other variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations, modifications and equivalents. In addition, the term “or” should be interpreted in an inclusive sense.