Abstract:
A portable device includes a battery, electronic circuitry, and a peak current provider that provides a peak current to the electronic circuitry. Power is supplied to the portable device by connecting a battery to a peak current provider, charging the peak current provider, and supplying a current from the battery to electronic circuitry of the portable device, when a current required by the electronic circuitry is less than or equal to a preset value, and disconnecting the battery from the peak current provider and supplying a current from the peak current provider to the electronic circuitry, when a current required by the electronic circuitry is greater than the preset value.

Description:
[0001]     This application claims the benefit of Korean Patent Application No.10-2005-0079075, filed on Aug. 26, 2005, which is hereby incorporated by reference in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to portable devices and, more particularly, to an apparatus and method for conserving a charge of a battery in a portable device.  
         [0004]     2. Description of the Related Art  
         [0005]     There has been a recent proliferation of portable devices capable of performing multiple functions such as a communication function, a personal organizer function, a camera function, a game function, and/or a music player function. As these devices have been developed to perform functions at higher speeds, the power consumption of these devices has considerably increased. Accordingly, it is becoming more important to manage the power consumption of these devices effectively.  
         [0006]     To operate a portable device, a battery which supplies power to the portable device must have a charge of at least a minimum voltage, referred to as a cutoff voltage. When the battery charge decreases below this cutoff voltage, the portable device will shut off.  
         [0007]     For example, a conventional Global System for Mobile communications (GSM) mobile terminal utilizes a lithium-ion battery which has a capacity of 4.2 V. The conventional GSM mobile terminal has a cutoff voltage of 3.4 V, and will thus shut off when the charge of the battery drops below 3.4 V.  
         [0008]     Due to chemical properties of a battery, if an output current of the battery severely fluctuates, this causes the battery charge to drain quickly. In contrast, when the output current of the battery is relatively constant, the battery charge does not drain as quickly.  
         [0009]     Further, the larger the current the battery outputs, the more the battery charge drains.  
         [0010]      FIG. 1  shows a block diagram of a conventional portable device.  
         [0011]     The conventional portable device shown in  FIG. 1  includes a battery  12  which supplies power to electronic circuitry  16  of the device, which includes a Power Amplifier Module (PAM)  14  that directs connects to the battery  12 .  
         [0012]     The battery  12  supplies power to the electronic circuitry  16  through the PAM  14 . When the charge of the battery  12  drops below a cutoff voltage, the portable device shuts off.  
         [0013]     The electronic circuitry  16  is powered by an electric current provided by the battery  12 . During some modes of operation of the portable device, the current requirement of the electronic circuitry  16  fluctuates. For example,  FIG. 2  shows a graph of exemplary current requirements of the electronic circuitry  16  of a portable device while it is in a call communication mode. As shown in  FIG. 2 , the current requirement fluctuates between a peak current of 2.1 A, and a low current of 20 mA.  
         [0014]     Since the output current of the battery  12  severely fluctuates, this causes the battery charge to drain quickly, as mentioned above. When the charge of the battery  12  drops below the cutoff voltage, the portable device shuts off.  
       SUMMARY OF THE INVENTION  
       [0015]     An object of the present invention is to conserve the charge of a battery, thereby extending its usage time.  
         [0016]     To achieve at least this object, there is provided a portable device which includes a battery, electronic circuitry and a peak current provider that provides a peak current to the electronic circuitry.  
         [0017]     The peak current provider may include a current limiter, connected in series with the battery, which prevents the battery from outputting a current of more than a preset value. The portable device may also include a current limiter controller that controls the preset value. The preset value may be 0.4 A.  
         [0018]     The peak current provider may include a capacitor connected in parallel with the battery. The capacitor may have a capacitance of tens to hundreds of mE.  
         [0019]     The peak current provider may be integrated with the battery or the electronic circuitry. The electronic circuitry may include a power amplifier module connected to the peak current provider. The portable device may be a mobile communication terminal.  
         [0020]     There is also provided a method of supplying power to a portable device which includes connecting a battery to a peak current provider, charging the peak current provider, and supplying a current from the battery to electronic circuitry of the portable device, when a current required by the electronic circuitry is less than or equal to a preset value, and disconnecting the battery from the peak current provider and supplying a current from the peak current provider to the electronic circuitry, when a current required by the electronic circuitry is greater than the preset value.  
         [0021]     There is also provided a method of supplying power to a portable device which includes connecting a battery to a peak current provider, charging the peak current provider, and supplying a current from the battery to electronic circuitry of the portable device, when the portable device is idle or receiving a communication signal, and disconnecting the battery from the peak current provider and supplying a current from the peak current provider to the electronic circuitry, when the portable device is transmitting a communication signal.  
         [0022]     Additional advantages and features of the invention will be set forth in the description which follows and will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     The present invention is described in the detailed description that follows, with reference to the following noted drawings which illustrate non-limiting examples of embodiments of the present invention, and in which like reference numerals represent similar parts throughout the drawings.  
         [0024]      FIG. 1  is a schematic block diagram showing a conventional portable device;  
         [0025]      FIG. 2  is a graph of current requirements of a conventional portable device;  
         [0026]      FIG. 3  is a schematic block diagram showing a portable device in accordance with an embodiment of the present invention;  
         [0027]      FIG. 4  is a schematic block diagram showing a portable device in accordance with an embodiment of the present invention;  
         [0028]      FIGS. 5A  to  5 C are graphs showing currents passing through nodes A, B and C in  FIG. 4 ; and  
         [0029]      FIG. 6  shows a simulation of a usage time of a battery of a mobile terminal in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]     An apparatus and method for conserving a charge of a battery of a portable device is described below with reference to  FIGS. 3 and 4 .  
         [0031]      FIG. 3  shows a block diagram of a portable device, such as, but not limited to, a mobile communication terminal. The portable device shown in  FIG. 3  includes a battery  32 , electronic circuitry  38  including a PAM  34 , and a peak current provider  36 , connected in series with the battery  32 , which supplies a peak current to the electronic circuitry  38  via the PAM  34 . The battery  32  provides a current to the peak current provider  36 , rather than providing a current directly to the PAM  34 .  
         [0032]     As shown in  FIG. 4 , the peak current provider  36  includes a current limiter  36 - 1  which limits a current from the battery  32  to a preset value, a current limiter controller  37  which controls the preset value of the current limiter  36 - 1 , and a capacitor  36 - 2  which connects to the PAM  34 , in parallel with the battery  32 . The current limiter  36 - 1  is connected in series with the battery  32 , and blocks a current from the battery  32  which exceeds the preset value.  
         [0033]     The current limiter controller  37  varies the preset value of the current limiter  36 - 1  according to current requirements of the electronic circuitry  38  of the portable device, For example, when the peak current requirement of the electronic circuitry  38  is high (such as, for example, when a user of the portable device is playing a game or operating a camera flash LED), the current limiter controller  37  increases the preset value of the current limiter  36 - 1 .  
         [0034]     The capacitor  36 - 2  supplies a peak current to the electronic circuitry  38 . In order to do so, the capacitor  36 - 2  stores a charge, which is replenished by the battery  32 . In a preferred embodiment, the capacitor  36 - 2  has a capacitance of tens to hundreds of mF,  
         [0035]     The peak current provider  36  may be integrated with either the battery  32  or the electronic circuitry  38 .  
         [0036]     An operation of the portable device described above is now described with reference to  FIGS. 5A-5C  and  FIG. 6 .  
         [0037]      FIG. 5A  illustrates the current requirements of the electronic circuitry  38  when the portable device is in an exemplary operation mode, such as a call communication mode. During this operation mode, the current requirements fluctuate between a peak current of 2.1 A, for example, and a low current of 20 mA, for example,  
         [0038]     In the following example, the preset value of the current limiter  36 - 1  is set to 0.4 A. When the electronic circuitry  38  requires the peak current of 2.1 A, the current limiter  36 - 1  will prevent the battery  32  from providing a current of 2.1 A to the electronic circuitry  38 , by cutting the battery  32  off from the PAM  34 , since 2.1 A is greater than the preset value of 0.4 A. Since the capacitor  36 - 2  is connected in parallel with the battery  32  to the PAM  34 , when the battery  32  is cut off from the PAM  34 , the capacitor  36 - 2  provides the required peak current to the PAM  34 .  
         [0039]     When the electronic circuitry  38  requires a current less than or equal to the preset value of 0.4 A, the current limiter  36 - 1  does not cut the battery  32  off from the PAM  34 , and thus the battery  32  remains connected to the PAM  34 . As the battery  32  provides current to the PAM  34 , it simultaneously recharges the capacitor  36 - 2 .  
         [0040]      FIG. 5A  is a graph of the current passing through node A of  FIG. 4 , i.e., the input to PAM  34 , while the portable device is in a call communication mode. When the portable device transmits a communication signal, 2.1 A of current is provided to the electronic circuitry  38  via the PAM  34 . When the portable device is idle, or is receiving a communication signal, only 20 mA of current are provided to the PAM  34 . In the embodiment illustrated in  FIG. 5A , the transmit period of the portable device is 577 μs, and the receive/idle period is 4.0 ms.  
         [0041]     During the transmit period, since the peak current of 2.1 A exceeds the preset value of 0.4 A, the current limiter  36 - 1  cuts the battery  32  off from the PAM  34 , which results in the capacitor  36 - 2  providing the peak current of 2.1 A to the PAM  34 .  
         [0042]     However, during the receive/idle period, since the current of 20 mA does not exceed the preset value of 0.4 A, the current limiter  36 - 1  does not cut the battery  32  off from the PAM  34 , and the current of 20 mA is provided to the PAM  34  by the battery  32 . Simultaneously, the battery  32  recharges the capacitor  36 - 2 .  
         [0043]      FIG. 5B  is a graph of the current passing through node B of  FIG. 4 , i.e., the output of capacitor  36 - 2 , and  FIG. 5C  is a graph of the current passing through node C of  FIG. 4 , i.e., the output of battery  32 . As shown in  FIG. 5C , the current output by the battery  32  is relatively constant and does not severely fluctuate.  
         [0044]      FIG. 6  is a graph showing a result of a simulation of a usage time of a battery utilizing the apparatus and method described above. The simulation was performed using a mobile communication terminal with a transmission (TX) level of  5 . Line ‘A’ represents the battery voltage of a conventional mobile communication terminal, and line ‘B’ represents the battery voltage of a mobile communication terminal utilizing the peak current provider described above.  
         [0045]     As shown in  FIG. 6 , the usage time of the battery of the mobile communication terminal utilizing the peak current provider described above was 13 hours and 35 minutes, while the usage time of the conventional mobile communication terminal was only 12 hours and 35 minutes.  
         [0046]     Since the maximum output current of a battery utilizing a peak current provider as described above is significantly less than a peak current (e.g., 0.4 A versus 2.1 A), a maximum voltage drop of the battery is lower than it would be otherwise. As a result, a cutoff voltage of a portable device utilizing the peak current provider can be set to a lower value (e.g., 3.0 V rather than 3.4 V), which contributes to extending the usage time of the battery.  
         [0047]     Thus, as the apparatus and method described above relieves a battery from outputting a peak current, it is capable of extending the usage time of the battery.  
         [0048]     The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.  
         [0049]     The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.  
         [0050]     One or more embodiments of the disclosure may be referred to herein, individually and/or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any particular invention or inventive concept Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.  
         [0051]     The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.  
         [0052]     Although the invention has been described with reference to an exemplary embodiment, it is understood that the words that have been used are words of description and illustration, rather than words of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiment is not limited by any of the details of the foregoing description, unless otherwise specified. Rather, the above-described embodiment should be construed broadly within the spirit and scope of the present invention as defined in the appended claims. Therefore, changes may be made within the metes and bounds of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the invention in its aspects.