Abstract:
A power control system used in a computer system includes decision logic for outputting a decision voltage based on detection of an operational state of the computer system. The power control system includes a voltage control unit, having at least two resistors and a switch, for outputting a set voltage based on an on and off state of the switch determined by the decision voltage. A power supply circuit provides an output voltage to the computer system based on the set voltage.

Description:
BACKGROUND OF INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to a power control system used in a computer system, and more particularly, to a power control system that can provide various operating voltages to the computer system according to different states of the computer system.  
         [0003]     2. Description of the Prior Art  
         [0004]     With the rapid development of information technology, computer systems play important roles in modernizing many companies and are widely used in practically every industry. Consequently, the manufacturing of portable computers, including PDAs and notebooks, has become a mainstream business in the computer industry. In order to utilize the portable computer systems without an external power supply, users require batteries to provide sufficient power to the computer system. However, the power stored in the battery is exhaustible, and the operating time of the computer system is limited by the power capacity of the battery. Therefore, how to increase the time for which the battery provides electricity for the computer system has become a critical issue.  
         [0005]     Please refer to  FIG. 1 , which is a functional block diagram of a computer system  10  according to the prior art. The computer system  10  includes a processor  12 , a power supply circuit  14 , a battery  16 , and a voltage unit  18 . The processor  12  is used for controlling operations of the computer system  10  and the battery  16  is used for providing a stable DC voltage Vin. The battery  16  can also be used to output a set voltage Vset to the power supply circuit  14  through two resistors R 1 , R 2  of the voltage unit  18 . Therefore, the set voltage Vset is equal to the DC voltage Vin multiplied by a constant of R 2 /(R 1 +R 2 ). The power supply circuit  14  is used to output an operating voltage Vout to the processor  12  and other circuitry of the computer system  10  according to the set voltage Vset. The higher the set voltage Vset, the higher the outputted operating voltage Vout is.  
         [0006]     When the computer system is used for entertaining purposes, playing a DVD/VCD, or operating in an idle state, the computer system  10  is in a light-loaded state. On the other hand, the computer system  10  can also be in a heavy-load state, such as playing  3 D images. Please refer to  FIG. 2  and  FIG. 3 .  FIG. 2  is a voltage variation diagram of the processor  12  when the prior-art computer system  10  is in the heavy-load state, and  FIG. 3  is a voltage variation diagram of the processor  12  when the prior-art computer system  10  is in the light-load state. Please notice that although  FIG. 2  and  FIG. 3  only show the voltage variation of the processor  12 ,  FIG. 2  and  FIG. 3  can represent the voltage variations of other circuitries in the computer system  10  because the voltage variations of other circuitries in the computer system  10  are similar to those of the processor  12  in both the light-load state and the heavy-load state.  
         [0007]     Generally, the operating voltage of the processor  12  is not a fixed value, operating at around 3.3 Volts (+/−10%). In other words, the processor  12  and other circuitries of the computer system  10  can operate normally when the corresponding operating voltages are higher than 3V. As shown in  FIG. 2 , the operating voltage of the processor  12  varies volatilely ALAllen Lu Please change the word to “volatilely”.in the heavy-load state and sometimes the operating voltage may reach the lower limit of the operating voltage, 3.0V. On the other hand, the operating voltage of the processor  12  varies slimly ALAllen Lu Please change the word to “slimly”.in the light-load state, and the operating voltage remains at a standard voltage value of 3.3V.  
         [0008]     Please refer to  FIG. 1 . The battery  16  can be used to provide the stable DC voltage Vin and the voltage unit  18  can be used to output the set voltage Vset (=Vin*R 2 /(R 1 +R 2 )). The set voltage Vset may affect the outputted operating voltage Vout. Moreover, regarding the prior-art computer system  10 , the set voltage remains unchanged either in the light-load state or in the heavy-load state, and the outputted operating voltage Voutcausally remains unchanged.  
         [0009]     For the computer system  10  to operate normally in the heavy-load state, the set voltage has to remain at a larger voltage value to achieve greater operating voltage Vout. The above-mentioned approach, which maintains the computer system  10  operating normally in the heavy-load state, lacks ALAllen Lu Please replace “is lacking in” to “lacks”.flexibility. Moreover, the above-mentioned approach will lead to a power waste of the battery because the computer system  10  still has to be provided with a large operating voltage Vout in the light-load state.  
       SUMMARY OF INVENTION  
       [0010]     It is therefore a primary objective of the claimed invention to provide a power control system that can provide various operating voltages to the computer system according to different states of the computer system to solve the above-mentioned problems.  
         [0011]     According to the claimed invention, a power control system used in a computer system is disclosed. The power control system includes a decision logic for detecting states of the computer system to output a decision voltage and a voltage control unit for outputting a set voltage according to the decision voltage outputted from the decision logic.  
         [0012]     The voltage control unit includes a first resistor electrically connected to a voltage source, a second resistor electrically connected to the first resistor in series connection, and a switch circuit electrically connected to the first resistor in parallel connection and electrically connected to the decision logic. The switch circuit turns on or turns off according to the decision voltage outputted from the decision logic so that the voltage control unit can output the set voltage. The power control system further comprises a power supply circuit for generating an output voltage for the computer system according to the set voltage.  
         [0013]     An advantage of the claimed invention is that the voltage control unit can determine various states of the computer system according to the decision voltage of the decision logic, and can provide various operating voltages to the computer system according to the different states of the computer system, so that a waste of the battery power can be avoided in the light-load state, and an increase of the time by which the battery provides electricity for the computer system can be achieved.  
         [0014]     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0015]      FIG. 1  is a functional block diagram of a computer system according to the prior art.  
         [0016]      FIG. 2  is a voltage variation diagram of a processor in the heavy-load state.  
         [0017]      FIG. 3  is a voltage variation diagram of the processor in the light-load state.  
         [0018]      FIG. 4  is a functional block diagram of a first embodiment of a computer system according to the present invention.  
         [0019]      FIG. 5  is a diagram showing a detecting signal outputted by a south bridge chip in a heavy-load state.  
         [0020]      FIG. 6  is a diagram showing another detecting signal outputted by a south bridge chip in a light-load state.  
         [0021]      FIG. 7  is a diagram showing both the DC detecting voltage and the reference voltage respectively in a light-load state and in a heavy-load state.  
         [0022]      FIG. 8  is a functional block diagram of another computer system according to the present invention.  
         [0023]      FIG. 9  is a functional block diagram of another computer system according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0024]     Please refer to  FIG. 4 , which is a functional block diagram of a first embodiment of a computer system  30  according to the present invention. The computer system  30  includes a processor  32 , a battery  36 , and a power control system  20 . The power control system  20  includes a power supply circuit  34 , a voltage control unit  38 , and a decision logic  40 .  
         [0025]     The processor  32  is used for controlling operations of the computer system  30 , and the battery  36  is used for providing a DC voltage for operating the computer system  30 . The decision logic  40  is used for detecting states of the computer system  30  to output a decision voltage. The voltage control unit  38  is used to output a set voltage according to the decision voltage outputted from the decision logic  40 . The power supply circuit  34  is used to generate an output voltage for electric components of the computer system  30  according to the set voltage. Because the processor  32  occupies a large proportion of power consumption in the computer system  30 , the present embodiment takes the processor  32  as an example to describe the characteristics of the present invention.  
         [0026]     The decision logic  40  includes a south bridge chip  48 , a comparator  44 , and a voltage converter  46 . Please refer to both  FIG. 5  and  FIG. 6 .  FIG. 5  is a diagram showing a detecting signal outputted by the south bridge chip  48  when the computer system  30  is in a heavy-load state, and  FIG. 6  is a diagram showing another detecting signal outputted by the south bridge chip  48  when the computer system  30  is in a light-load state. A difference between the detecting signal at a node A (outputted by the south bridge chip  48 ) in the light-load state and the detecting signal at the node A in the heavy-load state can be realized by comparing  FIG. 5  with  FIG. 6 .  
         [0027]     The voltage converter  46  can be used to convert the detecting signal at the node A into a DC detecting voltage, and the voltage converter  46  can be implemented by an RC filter composed of a resistor and a capacitor. The generated DC detecting voltage will be compared with a reference voltage in the comparator  44 .  
         [0028]     Please refer to  FIG. 7 , which is a diagram showing both the DC detecting voltage at the node B (outputted by the voltage converter  46 ) and the reference voltage respectively in the light-load state and in the heavy-load state in the computer system  30 . As shown in  FIG. 7 , if a proper reference voltageVref is determined, the comparator  44  can output the decision voltage of a logic “1” in the heavy-load state. On the other hand, the comparator  44  can output the decision voltage of a logic “0” in the light-load state.  
         [0029]     Please return to refer to  FIG. 4 . The voltage control unit  38  includes a first resistor R 1 , a second resistor R 2 , a third resistor R 3 , and a switch circuit  42 . The switch circuit  42  can be an NMOS transistor. As shown in  FIG. 4 , the drain of the NMOS transistor  42  is electrically connected to the first resistor R 1  and the third resistor R 3  at a node C. The source of the NMOS transistor  42  is electrically connected to the first resistor R 1  and the second resistor R 2  at a node E. The gate of the NMOS transistor  42  is electrically connected to the comparator  44  for receiving the decision voltage outputted from comparator  44 .  
         [0030]     When the decision voltage of the comparator  44  is a logic “1”, the decision logic  40  will determine that the computer system  30  is operating in the heavy-load state, and the NMOS transistor  42  will conduct. Then the first resistor R 1  can be neglected, and the set voltage Vset is equal to a value of Vin*R 2 /(R 2 +R 3 ). On the other hand, when the decision voltage of the comparator  44  is a logic “0”, the decision logic  40  will determine that the computer system  30  is operating in the light-load state, and the NMOS transistor  42  will not conduct. Therefore, the set voltage Vset is equal to a value of Vin*R 2 /(R 1 +R 2 +R 3 ).  
         [0031]     Obviously, the set voltage Vset is smaller in the light-load state than that in the heavy-load state. The power supply circuit  34  can be used to process various set voltages Vsets to generate various output voltages for the computer system  30 . Designers can properly control the value of the first resistor R 1  via the above-mentioned controlling method.  
         [0032]     On the premise that the output voltage Vout will not be affected in the heavy-load state, the output voltage Vout can be reduced in the light-load state. For instance, after selecting the proper first resistor R 1 , the set voltage Vset(=Vin*R 2 /(R 2 +R 3 )) in the heavy-load state can be controlled to generate the output voltage Vout of 3.3V through the power supply circuit  34 . The set voltage Vset(=Vin*R 2 /(R 1 +R 2 +R 3 )) in the light-load state can be used to generate the output voltage Vout of 3.0V through the power supply circuit  34 . Therefore, the power control system  20  can be used to reduce the operating voltage to the value of 3.0V in the light-load state instead of 3.3V, so that the computer system  30  can save the power when operating in the light-load state to efficiently utilize the battery  36 .  
         [0033]     Please refer to  FIG. 8 , which is a functional block diagram of a second embodiment of a computer system  50  according to the present invention. The present embodiment inherits the characteristics of the embodiment shown in  FIG. 4 . However, the power control system  70  of the computer system  50  shown in  FIG. 8  is slightly different from that shown in  FIG. 4  (the power control system  20  of the computer system  30 ). The switch circuit  54  of the voltage control unit  52  is a PMOS transistor instead of an NMOS transistor.  
         [0034]     When the decision voltage outputted from the decision logic  40  is a logic “0”, the switch circuit  54  will conduct. Therefore, the set voltage Vset is equal to the value of Vin*R 2 /(R 2 +R 3 ). When the decision voltage outputted form the decision logic  40  is a logic “1”, the switch circuit  54  will turn off. Therefore, the set voltage Vset is equal to the value of Vin*R 2 /(R 1 +R 2 +R 3 ). That is, if the decision logic  40  is designed to output the decision voltage of a logic “1” in the light-load state and to output the decision voltage of a logic “0” in the heavy-load state, the computer system  50  can significantly save the power when operating in the light-load state to efficiently utilize the battery  36 .  
         [0035]     When being implemented, the third resistor R 3  shown in  FIG. 4  and  FIG. 8  can be neglected. Please refer to  FIG. 9 , which is a functional block diagram of a third embodiment of a computer system  60  according to the present invention. The present embodiment also inherits the characteristics of the embodiment shown in  FIG. 4 . However, the power control system  80  of the computer system  60  shown in  FIG. 9  is slightly different from that shown in  FIG. 4  (the power control system  20  of the computer system  30 ). The power control system  80  does not include the third resistor R 3  of the computer system  30  shown in  FIG. 4 . That is, the node C is directly electrically connected to the battery  36 . Therefore, the voltage control unit  62  shown in  FIG. 9  includes a first resistor R 1 , a second resistor R 2 , and a switch circuit  42 . The switch circuit  42  can be an NMOS transistor or a PMOS transistor. In the present embodiment, the switch circuit  42  is implemented with an NMOS transistor.  
         [0036]     In the heavy-load state, the conducted NMOS transistor  42  allows the set voltage Vset to become the value of Vin*R 2 /R 2  (=Vin). In the light-load state, the turned-off NMOS transistor  42  allows the set voltage Vset to become the value of Vin*R 2 /(R 1 +R 2 ). In addition, by changing some related settings of the power supply circuit  34 , the output voltage Vout can be outputted in various values according to different set voltages Vset.  
         [0037]     Please notice that the decision logic of the present invention can output the decision voltage via a current reader, a program code, or other devices that can be used to determine whether the computer system is in the light-load state or in the heavy-load state.  
         [0038]     In contrast to the prior-art techniques, the power control system of the present invention can provide various operating voltages to the computer system according to different states of the computer system. In other words, when the computer system is in the light-load state, the power control system can output a lower operating voltage for the operating voltages of the electric components in the computer system operate at around 3.0 Volts (+/−10%) without large fluctuations in the light-load state. Therefore, the computer system of the present invention can normally operate with a lower operating voltage in the light-load state without the need of excess cost.  
         [0039]     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.