Abstract:
Disclosed is a power control apparatus of a complex terminal which includes a main battery and an auxiliary battery. The power control apparatus includes: a DC/DC converter for outputting an auxiliary power supplied from the auxiliary battery after adjusting a level of voltage of the auxiliary power to a required input voltage level of the complex terminal; a second voltage sensor for measuring voltage of a main power outputted from the main battery, and controlling the auxiliary power of the auxiliary battery to be inputted to the DC/DC converter before the measured voltage of the main power becomes lower than a predetermined voltage; and a first voltage sensor for interrupting supply of the main power from the main battery to the complex terminal and controlling the auxiliary power outputted from the DC/DC converter to be supplied to the complex terminal, when the measured voltage of the main power becomes lower than the predetermined voltage.

Description:
PRIORITY  
       [0001]     This application claims priority to an application entitled “Power Control Apparatus of a Complex Terminal” filed in the Korean Industrial Property Office on Aug. 22, 2003 and assigned Serial No. 2003-58335, the contents of which are hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a complex terminal, and more particularly to a power control apparatus of a complex terminal.  
         [0004]     2. Description of the Related Art  
         [0005]     In general, a complex terminal receives electric power from a rechargeable battery detachably assembled with the complex terminal. The complex terminal may lose data when power supply from the battery to the terminal is stopped due to reasons such as separation or discharge of the battery. In preparation for unexpected interruption of power supply due to separation or discharge of the battery as described above, the complex terminal includes a separate auxiliary battery built in the terminal, which can supply electric power to the terminal in such a case.  
         [0006]      FIG. 1  is a block diagram of a conventional complex terminal. Referring to  FIG. 1 , a conventional complex terminal may include a main battery  2  for supplying electric power, a phone module  4  for performing the function of a portable phone, and a PDA (Personal Digital Assistant) module  6  for performing the function of a personal information terminal or PDA. The PDA module  6  includes a PDA power supply  22 , a first switch  24 , a first voltage sensor  26 , a second voltage sensor  28 , a charger  32 , an auxiliary battery  34 , a second switch  36 , a third switch  30 , a DC/DC converter  38 , a PDA controller  40 , and a storage unit  42 . The PDA module  6  is operated by the electric power supplied from the main battery  2 .  
         [0007]     The first voltage sensor  26  of the PDA module  6  detects voltage applied from the main battery  2 . The first voltage sensor  26  directs the PDA module  6  to receive electric power from the auxiliary battery  34  instead of the main battery  2  when the detected voltage is lower than a predetermined value (e.g., 3.0 V). Here, while the power source to the PDA module  6  is switched from the main battery  2  to the auxiliary battery  34 , the voltage applied to the PDA controller  40  becomes unstable.  
         [0008]      FIG. 2  is a graph showing the voltage applied to the PDA controller  40  in a typical complex terminal. In the graph shown in  FIG. 2 , t 1  represents a time point at which the voltage applied from the main battery  2  to the PDA controller  40  begins to be lowered due to discharge of the main battery  2  or separation of the main battery  2  from the complex terminal.  
         [0009]     Referring back to  FIG. 1 , when the voltage of the electric power supplied from the main battery  2  becomes lower than a predetermined value (e.g., 3.0 V), the first voltage sensor  26  directs the first switch  24  and the second switch  36  to allow electric power to be supplied to the PDA controller  40  from the auxiliary battery  34  instead of the main battery  2 . Specifically, when the voltage of the electric power supplied from the main battery  2  becomes lower than a predetermined value (e.g., 3.0 V) due to discharge of the main battery  2  or separation of the main battery  2  from the complex terminal, the first voltage sensor  26  directs the first switch  24  to connect the DC/DC converter  38  with the PDA controller  40 , directs the second switch  36  to connect the auxiliary battery  34  with the DC/DC converter  38 , and notifies the PDA controller  40  that the electric power is supplied to the PDA controller  40  from the auxiliary battery  34  instead of the main battery  2 . When the voltage of the electric power supplied from the main battery  2  becomes lower than a second value (e.g., 3.2 V) due to discharge of the main battery  2  or separation of the main battery  2  from the complex terminal, the second voltage sensor  28  directs the third switch  30  to disconnect the charger  32  and the main battery  2  from each other, so as to prevent electric current from flowing backward from the charger  32  to the main battery  2 .  
         [0010]     When the auxiliary battery  34  and the DC/DC converter  38  are connected and the DC/DC converter  38  and the PDA controller  40  are connected, the PDA controller  40  can receive electric power from the auxiliary battery  34  instead of the main battery  2 . However, during the process wherein the connection between the auxiliary battery  34  and the DC/DC converter  38  and the connection between the DC/DC converter  38  and the PDA controller  40  are established, the voltage of the electric power supplied to the PDA controller  40  becomes unstable. This is because the electric power supplied through the DC/DC converter  38  from the auxiliary battery  34  is not instantly supplied to the PDA controller  40 . In other words, since the electric power is not instantly supplied to an input node of the PDA controller  40 , the voltage has an unstable portion as designated by C in  FIG. 2 . This unstable voltage may cause misoperation of the PDA module  6  and loss of data in the complex terminal.  
       SUMMARY OF THE INVENTION  
       [0011]     Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a power control apparatus of a complex terminal, which can stabilize voltage applied to a PDA module while electric power source is switched from a main battery to an embedded auxiliary battery, and thus can reduce loss of data in the complex terminal.  
         [0012]     It is another object of the present invention to provide a power control apparatus of a complex terminal, in which a DC/DC circuit for converting voltage of an embedded auxiliary battery can be more rapidly operated while electric power source is switched from a main battery to the auxiliary battery, so that the voltage applied to a PDA module can be stabilized and thus loss of data in the complex terminal can be reduced.  
         [0013]     In order to accomplish this object, there is provided a power control apparatus of a complex terminal which includes a main battery and an auxiliary battery, the power control apparatus comprising: a DC/DC converter for outputting an auxiliary power supplied from the auxiliary battery after adjusting a level of voltage of the auxiliary power to a required input voltage level of the complex terminal; a second voltage sensor for measuring voltage of a main power outputted from the main battery, and controlling the auxiliary power of the auxiliary battery to be inputted to the DC/DC converter before the measured voltage of the main power becomes lower than a predetermined voltage; and a first voltage sensor for interrupting supply of the main power from the main battery to the complex terminal and controlling the auxiliary power outputted from the DC/DC converter to be supplied to the complex terminal, when the measured voltage of the main power becomes lower than the predetermined voltage.  
         [0014]     In accordance with another aspect of the present invention, there is provided a power control apparatus of a complex terminal which includes an external main battery, an embedded auxiliary battery, and a PDA controller, the power control apparatus comprising: a PDA power supply for outputting a main power supplied from the main battery after adjusting a level of voltage of the main power to a required input voltage level of the PDA controller; a DC/DC converter for outputting an auxiliary power supplied from the auxiliary battery after adjusting a level of voltage of the auxiliary power to the input voltage level of the PDA controller; a first switch for selectively connecting the PDA controller to one of the PDA power supply and the DC/DC converter; a first voltage sensor for outputting an interrupt signal which notifies that the PDA controller cannot receive the main power from the main battery, and controlling the first switch to connect the PDA controller with the DC/DC converter so that the PDA controller can receive the auxiliary power from the auxiliary battery, when the voltage of the main power from the main battery becomes lower than a first voltage; a second switch for connecting or disconnecting the auxiliary battery and the DC/DC converter with or from each other; and a second voltage sensor for controlling the second switch to connect the auxiliary battery and the DC/DC converter with each other so that the auxiliary power of the auxiliary battery can be instantly applied to the PDA controller, when the voltage of the main power from the main battery becomes lower than a second voltage, wherein, when the PDA controller receives the interrupt signal and is connected with the DC/DC converter, the PDA controller instantly receives the auxiliary power from the auxiliary battery, enters into a sleep mode, and stores current data. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0016]      FIG. 1  is a block diagram of a conventional complex terminal;  
         [0017]      FIG. 2  is a graph showing voltage applied to a PDA controller in a typical complex terminal, which changes according to time when a main battery is separated or discharged;  
         [0018]      FIG. 3  is a block diagram of a complex terminal having a power control apparatus according to an embodiment of the present invention;  
         [0019]      FIG. 4  is a graph showing voltage applied to a PDA module, which changes according to time when a main battery is discharged, according to an embodiment of the present invention;  
         [0020]      FIG. 5  is a graph showing voltage applied to a PDA module, which changes according to time when a main battery is assembled with or separated from a complex terminal, according to an embodiment of the present invention; and  
         [0021]      FIG. 6  is a graph showing voltage applied to a PDA controller, which changes according to time when a main battery is discharged, or assembled with or separated from the complex terminal, according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]     Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.  
         [0023]     Referring to  FIG. 3 , a complex terminal according to an embodiment of the present invention roughly includes a main battery  100  supplying electric power, a phone module  200  performing the function of a portable phone, and a PDA module  300  performing the function of a personal information terminal or PDA.  
         [0024]     The phone module  200  includes a terminal power supply  202  and a terminal controller  204 . The terminal power supply  202  transfers electric power supplied from the main battery  100  to devices in the phone module  200 , such as the terminal controller  204 . The terminal controller  204  controls general operation of the phone module  200 .  
         [0025]     The PDA module  300  includes a PDA power supply  302 , a first switch  304 , a first voltage sensor  306 , a second voltage sensor  308 , a second switch  316 , a charger  312 , an auxiliary battery  314 , a third switch  310 , a DC/DC converter  318 , a PDA controller  320 , and a storage unit  322 .  
         [0026]     The PDA power supply  302  outputs the electric power supplied from the main battery  100  after adjusting the voltage level of the electric power to a required input voltage level of the PDA controller  320 .  
         [0027]     The first switch  304  is located between the PDA power supply  302 , the PDA controller  320 , and  381 , so as to connect the PDA power supply  302  and the PDA controller  320  or the PDA controller  320  and the DC/DC converter  318 .  
         [0028]     The first voltage sensor  306  senses the voltage of the electric power supplied from the main battery  100 . When the sensed voltage is higher than a first voltage (e.g., 3.0 V), the first voltage sensor  306  directs the first switch  304  to connect the PDA controller  320  with the PDA power supply  302  so that the PDA controller  320  can receive electric power from the main battery  100 . The first voltage has a magnitude capable of operating the PDA controller  320 , for example, 3.0 V. In contrast, when the sensed voltage is lower than the first voltage, the first voltage sensor  306  directs the first switch  304  to connect the DC/DC converter  318  and the PDA controller  320  so that the PDA controller  320  can receive electric power from the auxiliary battery  314 . Further, when the sensed voltage is lower than the first voltage, the first voltage sensor  306  sends an interrupt signal to the PDA controller  320 . The signal indicates that the PDA controller  320  cannot receive the electric power from the main battery  100 . The interrupt signal causes the PDA controller  320  to enter into a sleep mode.  
         [0029]     When the charger  312  is connected with the main battery  100 , the charger  312  charges the auxiliary battery  314  by means of the electric power supplied from the main battery  100 .  
         [0030]     The third switch  310  is located between the main battery  100  and the charger  312 , so as to connect or disconnect the main battery  100  and the charger  312 .  
         [0031]     The auxiliary battery  314  is charged through the charger  312 . When the auxiliary battery  314  has been charged, it can replace the main battery  100  in supplying electric power to the PDA controller  320 .  
         [0032]     The second switch  316  is located between the auxiliary battery  314  and the DC/DC converter  318 , so as to connect or disconnect the auxiliary battery  314  and the DC/DC converter  318 .  
         [0033]     When the DC/DC converter  318  has been connected with the auxiliary battery  314 , the DC/DC converter  318  outputs the electric power supplied from the auxiliary battery  314  after adjusting the voltage level of the electric power to a required input voltage level of the PDA controller  320 .  
         [0034]     The second voltage sensor  308  senses the voltage of the electric power supplied from the main battery  100 . When the sensed voltage becomes a second voltage (e.g., 3.2 V), the second voltage sensor  308  directs the third switch  310  to disconnect the main battery  100  and the charger  312  from each other, thereby preventing the auxiliary battery  314  from being discharged toward the main battery  100 . Further, when the sensed voltage becomes the second voltage, the second voltage sensor  308  directs the second switch  316  to connect the auxiliary battery  314  with the DC/DC converter  318  and adjusts the voltage level of the electric power supplied from the auxiliary battery  314  to a required input voltage level of the PDA controller  320 . The second voltage is higher than the first voltage by a difference, which is sufficient for normal operation of the PDA controller  320  before the PDA controller  320  receives the interrupt signal and enters into the sleep mode.  
         [0035]     The PDA controller  320  controls general operation of the PDA module  300 . The PDA controller  320  receives electric power from the main battery  100  when the voltage of the main battery  100  is higher than the first voltage and from the auxiliary battery  314  when the voltage of the main battery  100  is lower than or equal to the first voltage. When the PDA controller  320  has received the interrupt signal from the first voltage sensor  306 , which notifies that the PDA controller  320  cannot receive the electric power from the main battery  100 , the PDA controller  320  stops all the processes currently in progress, enters into the sleep mode (power-saving mode), and stores data of the complex terminal.  
         [0036]     A power control apparatus of a complex terminal, according to an embodiment of the present invention, operates the DC/DC converter  318  before the interrupt signal is inputted to the PDA controller  320 . This is different from a power control apparatus of a conventional complex terminal. As a result, the voltage of the electric power supplied through the DC/DC converter  318  from the auxiliary battery  314  can be instantly applied to the PDA controller  320 .  
         [0037]      FIG. 4  is a graph showing the voltage applied to the PDA module  300 , which changes according to time when the main battery  100  is discharged, according to an embodiment of the present invention.  FIG. 5  is a graph showing the voltage applied to the PDA module  300 , which changes according to time when the main battery  100  is attached to or separated from the complex terminal, according to an embodiment of the present invention.  FIG. 6  is a graph showing the voltage applied to the PDA controller  320  according to an embodiment of the present invention, which changes according to time when the main battery  100  is discharged, attached to, or separated from the complex terminal.  
         [0038]     Hereinafter, a method according to an embodiment of the present invention will be described in detail, which can reduce a phenomenon in which the voltage applied to the PDA controller  320  becomes unstable when the main battery  100  is discharged, or assembled with or separated from the complex terminal.  
         [0039]     In  FIG. 4 , t 1  represents a time point at which the voltage applied from the main battery  100  to the PDA module  300  begins to be lowered due to discharge of the main battery  100 . In  FIG. 5 , t 1  represents a time point at which the voltage applied from the main battery  100  to the PDA module  300  begins to be lowered due to separation of the main battery  100  from the complex terminal.  
         [0040]     In  FIGS. 4 and 5 , t 2  represents a time point at which the voltage applied to the PDA module  300  becomes the second voltage (e.g., 3.2 V) due to discharge or separation of the main battery  100 , and t 3  represents a time point at which the voltage applied to the PDA module  300  becomes the first voltage (e.g., 3.0 V).  
         [0041]     When the voltage of the electric power supplied from the main battery  100  reaches the second voltage while decreasing as described above, that is, at the time point t 2 , the second voltage sensor  308  directs the third switch  310  to disconnect the main battery  100  and the charger  312  from each other, thereby interrupting charge of the auxiliary battery  314 . Further, at the time point t 2 , the second voltage sensor  308  directs the second switch  316  to connect the auxiliary battery  314  and the DC/DC converter  318 , thereby enabling the electric power to be supplied from the auxiliary battery  314  to the DC/DC converter  318 .  
         [0042]     Further, at the time point t 3  at which the electric power supplied from the main battery  100  becomes lower than the first voltage, the first voltage sensor  306  transfers an interrupt signal to the PDA controller  320 , which notifies that the main battery  100  cannot supply the electric power. Further, at the time point t 3 , the first voltage sensor  306  directs the first switch  304  to connect the DC/DC converter  318  and the PDA controller  320 . Herein, the interval between t 2  and t 3  is several milliseconds. That is, a power control apparatus according to the present invention connects the auxiliary battery  314  and the DC/DC converter  318  with each other by means of the second switch  316  several milliseconds before the PDA controller  320  receives the interrupt signal. Therefore, at the time point t 3 , the PDA controller  320  can instantly receive the electric power through the DC/DC converter  318  simultaneously while receiving the interrupt signal. As a result, instability of the voltage applied to the PDA controller  320  can be reduced as shown in  FIG. 6  in the complex terminal according to the present invention, in comparison with the conventional complex terminal.  
         [0043]     According to experiments, when the PDA controller  320  was realized by a Dragonball-CPU, it took 800 μs for the PDA controller  320  to enter into the sleep mode after the interrupt signal was inputted. A time delay in the operation of the second voltage sensor  308  was about 100 μs, and a time delay in the operation of the DC/DC converter  318  was about 10 μs. Therefore, the interval between t 2  and t 3  is sufficient for normal application of the voltage to the PDA controller  320  before the PDA controller  320  enters into the sleep mode after receiving the interrupt signal.  
         [0044]     In the power control apparatus of a complex terminal according to the present invention as described above, the DC/DC converter is operated before an interrupt signal for entering the PDA controller into the sleep mode is outputted to the PDA controller. This is different from the operation of the power control apparatus of the typical complex terminal. Therefore, the present invention can reduce the instability of the voltage applied to the PDA controller, which may exist due to time it takes for the DC/DC converter to receive the electric power from the auxiliary battery and to supply the electric power to the PDA controller. That is, in the complex terminal according to the present invention, while electric power source is switched from the main battery to the embedded auxiliary battery, the DC/DC circuit for converting the voltage of the auxiliary battery is operated more rapidly, so that the voltage applied to the PDA module can be stabilized and thus loss of data in the complex terminal can be reduced.  
         [0045]     While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.