Patent Publication Number: US-8532717-B2

Title: Voltage indicating circuit for mobile phone battery

Description:
This is a continuation of International Application PCT/CN2010/075362, with an International Filing Date of Jul. 21, 2010, which claims priority to Chinese Application No. 200920174321.8, filed Dec. 9, 2009, each of which is incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to communication equipment, in particular to a voltage indicating circuit for a mobile phone battery. 
     BACKGROUND OF THE INVENTION 
     When a mobile phone is used, voltage of a mobile phone battery needs to be monitored in real time. There is generally a graphic indicator for the voltage or quantity of electricity of the battery on an interface of the mobile phone, and a user can judge a current status of the battery according to the indication icon. Moreover, it is necessary to give the user an alarm or a power-off prompt in a case of low voltage of the battery. 
     At present, a manner of Analog-Digital (A/D) conversion is generally used for detection on the circuit, specifically comprising: the voltage of the battery is firstly input to an A/D conversion module to be converted into a digital quantity and then transferred, by a system bus, to a mobile phone baseband module to be processed by software; and the software judges the range of the voltage of the battery by table lookup or comparison and then refreshes the icon on the interface according to the judgment result. 
       FIG. 1  is a block diagram of a common method for implementing a grading indicating circuit for the voltage of the battery. As shown in  FIG. 1 , the grading indicating circuit for the voltage of the battery is implemented by A/D conversion, and ADC in  FIG. 1  represents an A/D converter. 
     In implementation, the defects of the above method lie in: the current voltage value of the battery needs to be acquired by continuous query of the software, a time interval for each query is variable, and the query needs to be controlled by a processor thereby consuming resources of the processor; in addition, various errors are easy to be introduced as the A/D conversion needs the cooperation of a clock, therefore, it is necessary to calibrate the voltage of the battery of each mobile phone in a later period. 
     SUMMARY OF THE INVENTION 
     The present invention provides a voltage indicating circuit for a mobile phone battery to solve the problem of consuming the resources of the processor caused by querying the voltage of the battery by the software in the prior art. 
     An embodiment of the present invention provides a voltage indicating circuit for a mobile phone battery, comprising a battery, further comprising a mobile phone baseband module and a battery voltage detection module, wherein 
     power input terminals of the mobile phone baseband module and the battery voltage detection module are coupled with an anode of the battery, and a detection signal output terminal of the battery voltage detection module is coupled with a communication terminal of the mobile phone baseband module; 
     the battery voltage detection module detects an output voltage of the anode of the battery and outputs a mobile phone battery voltage detection signal to the mobile phone baseband module through the detection signal output terminal; and 
     the mobile phone baseband module receives the mobile phone battery voltage detection signal through the communication terminal and indicates a voltage of the battery according to the mobile phone battery voltage detection signal. 
     Preferably, the detection signal output terminal of the battery voltage detection module comprises at least two interrupt signal output terminals, the communication terminal of the mobile phone baseband module comprises at least two signal receiving terminals, and the interrupt signal output terminals and the signal receiving terminals are coupled in a one-to-one correspondence way; and 
     the battery voltage detection module outputs a group of corresponding interrupt signals through the at least two interrupt signal output terminals according to a position of the detected output voltage of the anode of the battery in preset different voltage ranges, and the mobile phone baseband module displays a range in which the voltage of the battery is located according to the group of interrupt signals received. 
     Preferably, there are two interrupt signal output terminals and two signal receiving terminals respectively. 
     Preferably, the communication terminal of the mobile phone baseband module is universal Input/Output (I/O) interfaces of a mobile phone baseband main chip. 
     Preferably, the battery voltage detection module comprises: 
     a first Low Dropout Regulator LDO ( 411 ) with an input terminal coupled with the anode of the battery and an output terminal being Vth 1 ; 
     a second LDO ( 412 ) with an input terminal coupled with the anode of the battery and an output terminal being Vth 2 ; 
     resistors R 1 , R 2  and R 3  coupled in series to form a first branch, wherein one terminal of the first branch is coupled with the anode of the battery and the other terminal of the first branch is grounded, and the output voltage of the anode of the battery is output as Vin 1  and Vin 2  after being divided by the first branch; 
     resistors R 4 , R 5  and R 6  coupled in series to form a second branch, wherein one terminal of the second branch is coupled with the anode of the battery and the other terminal of the second branch is grounded, and the output voltage of the anode of the battery is output as Vin 3  and Vin 4  after being divided by the second branch; 
     a first voltage comparator ( 413 ) with an in-phase input terminal coupled with the Vth 1 , an inversed-phase input terminal coupled with the Vin 1 , and an output terminal being O 1 ; 
     a second voltage comparator ( 414 ) with an in-phase input terminal coupled with the Vin 2 , an inversed-phase input terminal coupled with the Vth 2 , and an output terminal being O 2 ; 
     a third voltage comparator ( 415 ) with an in-phase input terminal coupled with the Vth 1 , an inversed-phase input terminal coupled with the Vin 3 , and an output terminal being O 3 ; 
     a fourth voltage comparator ( 416 ) with an in-phase input terminal coupled with the Vin 4 , an inversed-phase input terminal coupled with the Vth 2 , and an output terminal being O 4 ; 
     a first RS trigger ( 417 ) with an S interface coupled with the O 1 , an R interface coupled with the O 2 , and an output terminal being one interrupt signal output terminal of the battery voltage detection module; and 
     a second RS trigger ( 418 ) with an S interface coupled with the O 3 , an R interface coupled with the O 4 , and an output terminal being the other interrupt signal output terminal of the battery voltage detection module. 
     The present invention has the following advantages: 
     with the circuit provided by the embodiment of the present invention, the range in which the voltage of the battery is located can be obtained directly by the battery voltage detection module having a hysteresis function without the cooperation of a clock, the indication of the voltage of the battery can be refreshed quickly by transmitting the range to the universal I/O interfaces of the mobile phone baseband main chip through interruptions, and the current voltage value of the battery can be acquired without the continuous query of the software, so as to effectively reduce the burden of the software and solve the problems of dependency of A/D conversion on the clock and conversion error. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a common method for implementing a grading indicating circuit for the voltage of the battery in the background; 
         FIG. 2  is a schematic diagram showing the relationship between the voltage of the battery and the indication of the mobile phone in accordance with an embodiment of the present invention; 
         FIG. 3  is a schematic diagram showing the structure of a voltage indicating circuit for a mobile phone battery in accordance with an embodiment of the present invention; and 
         FIG. 4  is a schematic diagram showing the circuit of a battery voltage detection module having a hysteresis function in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     To solve the problem of consuming resources of a processor by querying the voltage of a battery by the software in the prior art, the technical solution provided by the embodiments of the present invention provides a voltage indicating circuit, having the hysteresis function, for a mobile phone battery, which detects the voltage of the battery completely by the hardware, has the hysteresis function, and can run in an interruption way. The embodiments of the present invention will be described below with reference to the drawings. 
       FIG. 2  is a schematic diagram showing the relationship between the voltage of a battery and an indication of a mobile phone. Due to the grading of the voltage of the mobile phone battery may be different in different mobile phones, in this embodiment, it is assumed that the voltage of the battery is graded into 3 levels (upward direction: below V 1 , V 1  to V 2 , and V 2  to 4.2V; and downward direction: V 3  to 4.2V, V 3  to V 4 , and below V 4 ), and corresponding indication bars of the voltage of the battery are: 
     upward direction, below V 1 : 0 bar, V 1  to V 2 : 1 bar, and V 2  to 4.2V: 2 bars; and 
     downward direction, V 3  to 4.2V: 2 bars, V 3  to V 4 : 1 bar, and below V 4 : 0 bar. 
       FIG. 2  is merely a specific implementation, and other changes can be made. For example, the jump threshold of a signal indication at upward direction is less than that of downward direction, i.e., V 1 &lt;V 4 , and V 2 &lt;V 3 . Moreover, the solution provided this embodiment is also suitable for other grading ways. 
       FIG. 3  is schematic diagram showing the structure of a voltage indicating circuit for a mobile phone battery. As shown in  FIG. 3 , the circuit comprises: a mobile phone baseband module  301 , a battery voltage detection module  302  having a hysteresis function, and a mobile phone battery  303 , wherein: 
     power input terminals of the mobile phone baseband module  301  and the battery voltage detection module  302  are coupled with an anode of the battery  303 , and a detection signal output terminal of the battery voltage detection module  302  is coupled with a communication terminal of the mobile phone baseband module  301 ; 
     the battery voltage detection module  302  detects an output voltage of the anode of the battery  303  and outputs a mobile phone battery voltage detection signal to the mobile phone baseband module  301  through the detection signal output terminal; and 
     the mobile phone baseband module  301  receives the mobile phone battery voltage detection signal through the communication terminal and indicates the voltage of the battery according to the mobile phone battery voltage detection signal. 
     In implementation, the voltage indicating circuit for a mobile phone battery comprises the mobile phone baseband module  301 , the battery voltage detection module  302  having the hysteresis function, and the mobile phone battery  303 , wherein the mobile phone battery  303  is coupled with other respective modules, and the detection signal output terminal of the battery voltage detection module  302  having the hysteresis function is coupled with the communication terminal of the mobile phone baseband module  301 . 
     In implementation, the mobile phone battery  303  supplies power to the mobile phone baseband module  301  and the battery voltage detection module  302 . 
     Specifically, the mobile phone battery  303  is coupled with respective modules to supply power to the respective modules. 
     Specifically, the battery voltage detection module  302  having the hysteresis function can be used for detecting and judging the current voltage of the battery to determine in which preset range the voltage is located, and outputting the corresponding detection signal to the mobile phone baseband module  301 . That is, the detection signal output terminal of the battery voltage detection module  302  comprises at least two interrupt signal output terminals, the communication terminal of the mobile phone baseband module  301  comprises at least two signal receiving terminals, and the interrupt signal output terminals and the signal receiving terminals are connected in a one-to-one correspondence way. 
     The battery voltage detection module  302  outputs a group of corresponding interrupt signals through the at least two interrupt signal output terminals according to the position of the detected voltage of the battery in preset different voltage ranges, and the mobile phone baseband module  301  judges the position of the voltage of the battery in the preset different voltage ranges according to the combination of received interrupt signals and displays the range in which the voltage of the battery is located according to the judgement result. 
     Specifically, when the voltage of the mobile phone battery changes, the battery voltage detection module  302  having the hysteresis function outputs a group of corresponding interrupt signals to the mobile phone baseband module  301  according to the change of the voltage of the battery, and the mobile phone baseband module  301  acquires the range in which the voltage of the battery is located according to this group of interrupt signals and refreshes the icon display of the interface. For example, when there are two detection signal output terminals, the corresponding relationship between the combination of the interrupt signals and the corresponding range can be: when the two detection signal output terminals output no interrupt signals, i.e., the two detection signal output terminals output interrupt signals with the combination of 00, the voltage of the battery is below V 1 , the indication is 0 bar; when the two detection signal output terminals output the interrupt signals with the combination of 01, the indication is the first bar; when the two detection signal output terminals output the interrupt signals with the combination of 10, the indication is the second bar; and when the two detection signal output terminals output the interrupt signals with the combination of 11, the indication is the third bar. The specific quantity, combination and corresponding relationship of the interrupt signals can be set flexibly as required. 
     In implementation, the communication terminal of the mobile phone baseband module  301  can be universal I/O interfaces of the mobile phone baseband main chip. 
     In implementation, the universal I/O interfaces can be configured in an interruption mode to receive the interrupt signals from the battery voltage detection module  302 . 
     Specifically, the communication terminal of the mobile phone baseband module  301  can be universal I/O interfaces of the mobile phone baseband main chip. Such universal I/O interfaces can be configured in an interruption mode to receive the interrupt signals from the battery voltage detection module  302  having the hysteresis function. 
     In specific implementation, referring to  FIG. 3 , the mobile phone battery  303  supplies power to the battery voltage detection module  302  having the hysteresis function and the mobile phone baseband module  301 , wherein the battery voltage detection module  302  having the hysteresis function judges the range in which the current voltage of the battery is located according to the change of the voltage of the battery and outputs the judgement result to the universal I/O interfaces of the baseband main chip of the mobile phone baseband module  301 , that is, the output ports S 1  and S 2  of the battery voltage detection module  302  having the hysteresis function are respectively coupled with the universal I/O interfaces, GPIO 1  and GPIO 2 , of the baseband main chip of the mobile phone baseband module  301 . 
     When the voltage of the battery increases and is below V 1 , both S 1  and S 2  output high level, and the universal I/O interfaces, GPIO 1  and GPIO 2 , of the baseband main chip detect the input level, judge that the number of bars of the voltage of the battery at this moment should be 0, and refresh the display of the interface as 0 bars. When the voltage of the battery is above V 1  but below V 2 , S 1  outputs low level and S 2  outputs high level, and the universal I/O interfaces, GPIO 1  and GPIO 2 , of the baseband main chip detect the input level, judge that the number of bars of the voltage of the battery at this moment should be 1, and refresh the display of the interface as 1 bar. When the battery voltage is above V 2 , both S 1  and S 2  output low level, and the universal I/O interfaces, GPIO 1  and GPIO 2 , of the baseband main chip detect the input level, judge that the number of bars of the voltage of the battery at this moment should be 2, and refresh the display of the interface as 2 bars. 
     When the voltage of the battery decreases and is above V 3 , both S 1  and S 2  output low level, and the universal I/O interfaces, GPIO 1  and GPIO 2 , of the baseband main chip detect the input level, judge that the number of bars of the voltage of the battery at this moment should be 2, and refresh the display of the interface as 2 bars. When the voltage of the battery is below V 3  but above V 4 , S 1  outputs low level and S 2  outputs high level, and the universal I/O interfaces, GPIO 1  and GPIO 2 , of the baseband main chip detect the input level, judge that the number of bars of the voltage of the battery at this moment should be 1, and refresh the display of the interface as 1 bar. When the voltage of the battery is below V 4 , both S 1  and S 2  output high level, and the universal I/O interfaces, GPIO 1  and GPIO 2 , of the baseband main chip detect the input level, judge that the number of bars of the battery voltage at this moment should be 0, and refresh the display of the interface as 0 bars. 
     In implementation, the battery voltage detection module  302  can output detection signals of S 1  and S 2  by taking a Voltage of Battery (VBAT) as the input. 
       FIG. 4  is a schematic diagram showing the circuit of the battery voltage detection module having the hysteresis function. As shown in  FIG. 4 , in implementation, the battery voltage detection module can comprise: 
     a first Low Dropout Regulator (LDO)  411  with an input terminal coupled with the anode of the battery and an output terminal being V th1 ; 
     a second LDO  412  with an input terminal coupled with the anode of the battery and an output terminal being V th2 ; 
     resistors R 1 , R 2  and R 3  coupled in series to form a first branch, wherein one terminal of the first branch is coupled with the anode of the battery and the other terminal of the first branch is grounded, and the voltage of the battery is output as V in1  and V in2  after being divided by the first branch; 
     resistors R 4 , R 5  and R 6  coupled in series to form a second branch, wherein one terminal of the second branch is coupled with the anode of the battery and the other terminal of the second branch is grounded, and the voltage of the battery is output as V in3  and V in4  after being divided by the second branch; 
     a first voltage comparator  413  with an in-phase input terminal coupled with V th1 , an inversed-phase input terminal coupled with V in1 , and an output terminal being O 1 ; 
     a second voltage comparator  414  with an in-phase input terminal coupled with V in2 , an inversed-phase input terminal coupled with V th2 , and an output terminal being O 2 ; 
     a third voltage comparator  415  with an in-phase input terminal coupled with V th1 , an inversed-phase input terminal coupled with V in3 , and an output terminal being O 3 ; 
     a fourth voltage comparator  416  with an in-phase input terminal coupled with V in4 , an inversed-phase input terminal coupled with V th2 , and an output terminal being O 4 ; 
     a first RS trigger  417  with an S interface coupled with O 1 , an R interface coupled with O 2 , and an output terminal being one interrupt signal output terminal of the battery voltage detection module; and 
     a second RS trigger  418  with an S interface coupled with O 3 , an R interface coupled with O 4 , and an output terminal being the other interrupt signal output terminal of the battery voltage detection module. 
     In implementation, referring to  FIG. 4 , it can be seen that the battery voltage detection module having the hysteresis function outputs detection signals of S 1  and S 2  by taking the voltage of the battery, V BAT , as the input. The first LDO  411  and the second LDO  412  are low dropout regulators, with the input voltage being V BAT , and output voltage being V th1  and V th2  respectively. V in1  and V in2  are the values obtained by dividing V BAT  through resistors R 1 , R 2  and R 3 , and V in3  and V in4  are the values obtained by dividing V BAT  through resistors R 4 , R 5  and R 6 . The first voltage comparator  413 , the second voltage comparator  414 , the third voltage comparator  415  and the fourth voltage comparator  416  are four voltage comparators, wherein the in-phase input terminal of the first voltage comparator  413  is V th1 , the reversed-phase input terminal of the first voltage comparator  413  is V in1 , and the output of the first voltage comparator  413  is O 1 ; the in-phase input terminal of the second voltage comparator  414  is V in2 , the reversed-phase input terminal of the second voltage comparator  414  is V th2 , and the output of the second voltage comparator  414  is O 2 ; the in-phase input terminal of the third voltage comparator  415  is V th1 , the reversed-phase input terminal of the third voltage comparator  415  is V in3 , and the output of the third voltage comparator  415  is O 3 ; the in-phase input terminal of the fourth voltage comparator  416  is V in4 , the reversed-phase input terminal of the fourth voltage comparator  416  is V th2 , and the output of the fourth voltage comparator  416  is O 4 . The first RS trigger  417  and the second RS trigger  418  are RS triggers. The working process of the whole circuit can be as follows. 
     Suitable R 1 , R 2 , R 3 , R 4 , R 5  and R 6 , the output V th1  of LDO  411  and the output V th2  of LDO  412  are selected, so as to obtain the following: 
     
       
         
           
             
               
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     When the voltage of the battery increases: 
     when V BAT ≦V 4 , V th1 ≧V in1 , V th2 &gt;V in2 , V th1 &gt;V in3 , V th2 &gt;V in4 , at this time, O 1  is high level, O 2  is low level, O 3  is high level, and O 4  is low level, then S 1  and S 2  are both high level; 
     when V 4 &lt;V BAT ≦V 1 , V th1 &lt;V in1 , V th2 ≧V in2 , V th1 &gt;V in3 , V th2 &gt;V in4 , at this time, O 1  is low level, O 2  is low level, O 3  is high level, and O 4  is low level, then S 1  and S 2  are still high level; 
     when V 1 &lt;V BAT ≦V 3 , V th1 &lt;V in1 , V th2 &lt;V in2 , V th1 ≧V in3 , V th2 &gt;V in4 , at this time, O 1  is low level, O 2  is high level, O 3  is high level, and O 4  is low level, then S 1  is inverted to low level and S 2  is still high level; 
     when V 3 &lt;V BAT ≦V 2 , V th1 &lt;V in1 , V th2 &lt;V in2 , V th1 &lt;V in3 , V th2 ≧V in4 , at this time, O 1  is low level, O 2  is high level, O 3  is low level, and O 4  is low level, then S 1  is still low level and S 2  is still high level; and 
     when V 2 &lt;V BAT &lt;4.2V, V th1 &lt;V in1 , V th2 &lt;V in2 , V th1 &lt;V in3 , V th2 &lt;V in4 , at this time, O 1  is low level, O 2  is high level, O 3  is low level, and O 4  is high level, then S 1  and S 2  are both low level. 
     Similarly, when the voltage of the battery decreases, the output results of S 1  and S 2  are as follows: 
     when V 3 ≦V BAT &lt;4.2V, S 1  and S 2  are both low level; 
     when V 4 ≦V BAT &lt;V 3 , S 1  is still low level, and S 2  is inverted to high level; and 
     when V BAT &lt;V 4 , S 1  and S 2  are both high level. 
     The above is only an example, and various changes can be made. For example, the input signals of the in-phase input terminals and inversed-phase input terminals of the voltage comparators  413 ,  414 ,  415  and  416  can be customized, and the output logics of S 1  and S 2  will be different according to different definitions. 
     In addition, by using the integrated circuit technology, this circuit can also be encapsulated in an intelligent card (IC) to be used by a user. 
     The battery voltage detection module of this embodiment effectively realizes the hysteresis function through the resistors and voltage comparators, so as to avoid the unnecessary change of the graphic display of the voltage of the battery caused by the slight change of the voltage of the battery. 
     Obviously, various modifications and variations for the present invention can be made by those skilled in the art within the spirit and scope of the present invention. By doing so, if such modifications and variations of the present invention are in the scope of the claims and equivalents thereof, the present invention is intended to include such modifications and variations.