Abstract:
A system for inhibiting the excessive discharge of a battery 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 to monitor said power, wherein the fuel gauge enters a standby mode upon determining that a voltage supplied by the battery is at or below a voltage threshold and that a capacity of the battery is at or below a capacity threshold.

Description:
BACKGROUND 
       [0001]    Lithium ion batteries are often used to power consumer electronics, such as smart phones, tablets, laptops, video cameras and handheld game consoles. Various operating conditions may result in an excessive discharge of the battery in such a device. For example, allowing the device to remain unused for extended periods of time may result in a progressive electrode breakdown. In some cases, such excessive battery discharge may result in potentially dangerous operating conditions. 
       SUMMARY 
       [0002]    At least some of the embodiments disclosed herein are directed to a system for inhibiting the excessive discharge of a battery in an electronic device, comprising: a battery to supply power to the electronic device; and a fuel gauge coupled to the battery to monitor said power, wherein the fuel gauge enters a standby mode upon determining that a voltage supplied by the battery is at or below a voltage threshold and that a capacity of the battery is at or below a capacity threshold. At least some of these embodiments may be supplemented by one or more of the following concepts, in any order or in any combination: wherein the battery is a lithium ion battery; wherein the fuel gauge enters said standby mode if and only if the fuel gauge determines that the voltage supplied by the battery is at or below said voltage threshold and that said capacity of the battery is at or below the capacity threshold; wherein the system determines said capacity of the battery using a Coulomb counting technique; wherein said standby mode is the lowest power mode available on said fuel gauge; wherein, to enter the standby mode, the fuel gauge stops a clock associated with the fuel gauge; wherein, to enter the standby mode, the fuel gauge opens a port associated with the fuel gauge; wherein the voltage and capacity thresholds are programmable; wherein the fuel gauge autonomously makes said determinations and autonomously enters the standby mode; wherein, upon detecting that said voltage has risen above the voltage threshold or that said capacity has risen above the capacity threshold, the fuel gauge exits the standby mode; wherein, to exit the standby mode, the fuel gauge enters a power mode higher than the standby mode; wherein said voltage threshold is in the range of 2.0 Volts to 2.5 Volts, inclusive; wherein said capacity threshold is in the range of 0% to 5%, inclusive. 
         [0003]    At least some embodiments are directed to an electronic device comprising a fuel gauge that enters a standby power mode upon detecting that a voltage supplied by a battery in said electronic device is at or below a voltage threshold and that a capacity of the battery is at or below a capacity threshold. 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 capacity threshold is between 0% and 1%, inclusive; wherein the electronic device is selected from the group consisting of: a smart phone, a tablet, a laptop, a video camera and a handheld game console; wherein said capacity is determined using a Coulomb counting technique. 
         [0004]    At least some embodiments are directed to a method for inhibiting the excessive discharge of a battery in an electronic device, comprising: determining that a voltage supplied by said battery is at or below a voltage threshold and that a capacity of said battery is at or below a capacity threshold; and causing a fuel gauge in said electronic device to autonomously enter a standby power mode based on said determination. 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 capacity threshold is between 0% and 0.5%, inclusive; wherein said standby power mode is the lowest power mode available on said fuel gauge. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    There are disclosed in the drawings and in the following description systems and methods for inhibiting excessive battery discharge using battery voltage and capacity measurements. In the drawings: 
           [0006]      FIG. 1  is a front view of a consumer electronic device. 
           [0007]      FIG. 2  is a block diagram of components within a consumer electronic device. 
           [0008]      FIG. 3  is a block diagram of components within a consumer electronic device and, more particularly, within a fuel gauge in the consumer electronic device. 
           [0009]      FIG. 4  is a flow diagram of a method usable to implement the techniques disclosed herein. 
       
    
    
       [0010]    It should be understood, however, that the specific embodiments given in the drawings and detailed description thereto do not limit the disclosure. On the contrary, they provide the foundation for one of ordinary skill to discern the alternative forms, equivalents, and modifications that are encompassed together with one or more of the given embodiments in the scope of the appended claims. 
       DETAILED DESCRIPTION 
       [0011]    Disclosed herein are methods and systems for inhibiting excessive battery discharge using battery voltage and capacity measurements. Generally, an electronic device implementing such techniques includes a battery that supplies power to the electronic device and a fuel gauge that monitors the battery. To prevent excessive battery discharge, the fuel gauge autonomously monitors multiple parameters associated with the battery—namely, a voltage provided by the battery and the remaining capacity of the battery—to determine whether to switch itself into a lower power mode, such as a standby mode. Typically, the fuel gauge switches to a lower power mode if it determines that the voltage provided by the battery has met or fallen below a specified voltage threshold and that a capacity of the battery has met or fallen below a specified capacity threshold. In preferred embodiments, both of these conditions must be met before the fuel gauge switches to a lower power mode. 
         [0012]      FIG. 1  is a front view of an illustrative consumer electronic device  100  that implements the systems and methods described herein. The electronic device  100  may be any suitable device that uses 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 device  100  includes a display screen  102  that is preferably a touch screen. It further includes various tactile input devices  104 , such as buttons arranged in various locations around the exterior of the electronic device  100 . Additional input and output devices, such as microphones and speakers, also may be incorporated within such a device. 
         [0013]      FIG. 2  is a block diagram of components within the illustrative consumer electronic device  100 . The electronic device  100  includes an application-specific integrated circuit (ASIC)  200  comprising processing logic  202  (e.g., a microprocessor), storage  206  coupled to the processing logic  202  and comprising software code  204  (e.g., an operating system or applications), input features  208  (e.g., buttons, touch screen, microphone), output features  210  (e.g., display screen that may be the same as the touch screen, speaker, haptic feedback motor), and a network interface  212  for communicating with other devices (e.g., via the Internet). Other components may be included on the ASIC  200 . The ASIC  200  is powered by a battery pack (“battery”)  214 . A fuel gauge  216  couples to the battery  214 . In at least some embodiments, the ASIC  200 , the fuel gauge  216  and the battery  214  couple to each other in a parallel configuration, so that the ASIC  200  may receive power from the battery  214  while the fuel gauge  216  monitors the output of the battery  214 . Further, in some embodiments the ASIC  200  may 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 ASIC  200 ) is powered by the battery  214 . In operation, and as described in greater detail with respect to  FIG. 3 , the fuel gauge  216  monitors the voltage output by the battery  214 , and the fuel gauge  216  also monitors a capacity of the battery  214 . If both the voltage and the capacity meet or drop below respective voltage and capacity thresholds, the fuel gauge  216  autonomously switches itself into a lower power consumption mode than its current power mode—for example, a sleep mode (also known as a standby mode). 
         [0014]      FIG. 3  is a block diagram of components within the consumer electronic device  100  and, more particularly, within the fuel gauge  216 . The block diagram of  FIG. 3  is conceptual in nature, meaning that at least some of the blocks represent functions performed by the various parts of the electronic device  100 . 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. 
         [0015]    Referring to  FIG. 3 , the electronic device  100  includes the battery  214  and the fuel gauge  216 , which couples in parallel to the battery  214 . The battery  214  includes a voltage source  300 , which couples to positive and negative terminals  302  and  304 . The negative terminal  304  couples to the fuel gauge  216  via a node  309 , which, in turn, couples to ground. Node  309  also is provided to the ASIC  200  or other suitable circuit logic being powered by the battery  214 . The positive terminal  302  couples to a Coulomb counter  306 , the output of which couples to a node  308 . Any suitable Coulomb counting device may be used. The node  308  couples to the fuel gauge  216  and is also provided to power the ASIC  200 . 
         [0016]    The fuel gauge  216  includes a voltage detection logic  310  that couples to node  308 ; a low voltage threshold register  312 ; a capacity detection logic  314  that receives an output of the Coulomb counter  306 ; a capacity threshold register  313  that couples to the capacity detection logic  314 ; and an AND gate  316  or similar logic that couples to the outputs of the voltage detection logic  310  and the capacity detection logic  314 . The output of the AND gate  316  (or comparable logic) is provided to a mode control logic  318 . The mode control logic  318  controls a clock  320  of the fuel gauge  216  and a port  322  through which the fuel gauge  216  couples to other devices in the electronic device  100  (e.g., the ASIC  200 ). 
         [0017]    In operation, the voltage source  300  delivers a potential across the terminals  302 ,  304 . The Coulomb counter  306  receives current via the terminal  302  and uses an internal resistance, in tandem with an internal timer, to determine a Coulomb count (i.e., current that accumulates over time). This Coulomb count reflects the total current discharge of the battery  214 . The capacity detection logic  314  compares the Coulomb count to an original capacity of the battery  214  to determine the present capacity of the battery  214  (also known as the remaining capacity of the battery  214 ). The scope of this disclosure is not limited to using a Coulomb counter as shown in  FIG. 3 . Other configurations are contemplated. For example, the resistor used to sense the current and the timer and processing logic used to count the accumulated current may be distributed in different parts of the electronic device  100 . 
         [0018]    The capacity detection logic  314  autonomously monitors the present capacity of the battery  214  and compares the capacity against a capacity threshold value that is provided by the programmable capacity threshold register  313  (e.g., using a comparator). The capacity threshold value may be set to any suitable value, and in at least some embodiments, this value is in the range of 0% to 5%, inclusive. In some embodiments, the value is in the range of 0% to 1%, inclusive. In some embodiments, the value is in the range of 0% to 0.5%, inclusive. If the capacity detection logic  314  determines that the capacity of the battery  214  meets or drops below the capacity threshold value, it generates a flag signal (e.g., a HIGH value on its output). This flag signal, which is otherwise LOW, is provided to the AND gate  316 . 
         [0019]    The voltage detection logic  310  autonomously monitors the output voltage of the battery  214 . In cases where a voltage drop is introduced into the connection between the voltage detection logic  310  and the battery  214  (e.g., by a Coulomb counter or other logic), the voltage detection logic  310  may be programmed or structured to correct for this voltage drop. The voltage detection logic  310  compares the output voltage of the battery  214  to a voltage threshold value provided by the programmable low voltage threshold register  312  (e.g., using a comparator). The low voltage threshold register  312  may be set to any suitable value, and in at least some embodiments, this value is in the range of 2.0 Volts to 2.5 Volts, inclusive. If the voltage detection logic  310  determines that the output voltage of the battery  214  meets or drops below the voltage threshold value, the logic  310  generates a flag signal (e.g., a HIGH value on its output). This flag signal, which is otherwise LOW, is provided to the AND gate  316 . 
         [0020]    The output of the AND gate  316  is provided to the mode control logic  318 . If the mode control logic  318  determines that the signal output by the AND gate  316  is HIGH, meaning that the outputs of both the logics  310 ,  314  are HIGH, then the mode control logic  318  switches the power mode of the fuel gauge  216  to a lower power mode than its present power mode. In at least some embodiments, the fuel gauge  216  is switched to the lowest power mode available for the fuel gauge  216 . In preferred embodiments, the lower power mode is a standby mode (or “sleep” mode), although other lower power modes also may be used. For example, the fuel gauge  216  may switch from an active mode to an operation mode; or from an operation mode to a relaxed mode; or from a relaxed mode to a standby mode. Any and all such variations are encompassed within the scope of the disclosure. 
         [0021]    To switch the fuel gauge  216  to a lower power mode, the mode control logic  318  may undertake any suitable action. For example and without limitation, the mode control logic  318  may disable the clock  320  used by the fuel gauge  216 . It may also open the port  322  through which the fuel gauge  216  communicates with the ASIC  200 . Other techniques for switching power modes are contemplated. 
         [0022]    In at least some embodiments, the voltage detection logic  310  and the capacity detection logic  314  continue to monitor the battery voltage and the Coulomb counter output, respectively, after the fuel gauge  216  is switched to a lower power mode. If the voltage detection logic  310  determines that the voltage provided by the battery  214  is no longer at or below the voltage threshold value, or if the capacity detection logic  314  determines that the capacity of the battery  214  is no longer at or below the capacity threshold value, the output of the AND gate  316  becomes LOW, and the mode control logic  318  switches the fuel gauge power mode to a higher power mode. 
         [0023]      FIG. 4  is a flow diagram of a method  400  that implements the techniques disclosed herein. The method  400  begins by detecting the battery voltage (step  402 ). Next, the method  400  includes determining whether the battery voltage is at or below the programmed voltage threshold value (step  404 ). If not, control of the method returns to step  402 . Otherwise, the method  400  includes determining whether the capacity of the battery is at or below the programmed capacity threshold value (step  406 ). If not, control of the method returns to step  402 . Otherwise, the method  400  includes the fuel gauge autonomously switching itself into a lower power mode, such as a standby mode (step  408 ). The steps of the method  400  may be modified as desired, including by adding, deleting or rearranging steps. 
         [0024]    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.