Abstract:
A computer system including a power supply and N main boards is provided, herein N is an integer greater than 1. The power supply generates a main power and a standby power. The N main boards respectively correspond to one standby voltage. The 1 st  to the (N−1) th  main boards respectively generate the corresponding standby voltage by the main power in a power-on state, and respectively generate the corresponding standby voltage by the standby power in a power-off state. The N th  main board generates the corresponding standby voltage by the main power in the power-on and power-off state.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 97146012, filed Nov. 27, 2008. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of specification. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a computer system. More particularly, the present invention relates to a computer system that can completely drive electronic elements needed to be driven in a main board in a power-off state. 
     2. Description of Related Art 
     With the technology development in recent years, a computer system has unavoidably become an indispensable information processing tool in modern human life. The computer system can satisfy all of people&#39;s needs in work, travel, and entertainment. For example, information such as personal financial statements, banking account passwords, confidential documents, photos, private letters, commercial documents and intellectual creations can all be stored by the computer system in a hard disc of the computer system. 
     The power efficiency of the computer system reduces when people are only temporarily away from the computer. Due to the above issue, the computer system is usually disposed with a corresponding power management mechanism to turn off some electronic elements in the computer system appropriately to achieve the goal of reducing power consumption. In the power management mechanism, a power supply inside the computer system provides two types of power: a main power and a standby power. Herein, the main power is only provided to the main board when the computer system is in a power-on state, and the standby power is provided to the main board when the main board is electrically connected to the power supply. 
     However, sometimes, the standby power provided by the power supply may not satisfy the demand of the main board so that the electronic elements driven by the standby power in the computer system can not function normally and thereby lower the operating function of the computer system. Although the operating function of the computer system can be acquired by replacing the power supply, disadvantages such as higher hardware cost and lower source utilization efficiency may result. 
     SUMMARY OF THE INVENTION 
     The present invention provides a computer system that can maintain required operating functions of the computer system without replacing a power supply. 
     A computer system including a power supply and N main boards is provided in the present invention, herein, N is an integer greater than 1. The power supply generates a main power and a standby power. The N main boards each corresponds to one standby voltage. Here, the 1 st  to the (N−1) th  main boards each generates the corresponding standby voltage by the main power in a power-on state and generates the corresponding standby voltage by the standby power in a power-off state. On the other hand, the N th  main board generates the corresponding standby voltage by the main power in both the power-on and the power-off states. 
     In one embodiment of the present invention, the N main boards each includes a controller, a switch, and a first voltage converter. Herein, the controller receives a model identification code, and outputs a standby voltage startup signal and a power enable signal when the model identification code conforms to an identification code of the main board corresponding to the controller. Moreover, the power supply outputs the main power and a main voltage startup signal to the N th  main board. In addition, the power supply outputs the main power and the main voltage startup signal to one or a lot of main boards among the 1 st  to the (N−1) th  main boards when the one or the lot of main boards of is/are in the power-on state. 
     Accordingly, the main power and the main voltage startup signal are then outputted to the main board corresponding to the controller. On the other hand, the switch receives the main power and the standby power and determines whether the main power or the standby power is outputted according to the standby voltage startup signal. Thus, the first voltage converter then converts the power from the switch to the corresponding standby voltage. 
     In light of the foregoing, a main board of the computer system in the present invention uses the main power of the computer system to generate the standby voltage of the main board whether the computer system is in the power-on state or the power-off state. Therefore, the electronic elements that need to be driven in the main board will then be driven completely and thereby allow the computer system to achieve required operating functions without replacing the power supply. 
     In order to make the aforementioned and other features and advantages of the present invention more comprehensible, several embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a schematic circuit block diagram of a computer system according to an embodiment of the present invention. 
         FIG. 2  is a schematic circuit block diagram of a main board driven by a power supply according to an embodiment of the present invention. 
         FIG. 3  is a table of identification codes of a particular main board and the main board. 
         FIG. 4  is a schematic circuit block diagram of a main board driven by a power supply according to another embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 1  is a schematic circuit block diagram of a computer system according to an embodiment of the present invention. Referring to  FIG. 1 , a computer system  100  includes a power supply  110  and a plurality of main boards  120 - 150 . Here, the main boards  120 - 150  are all electrically connected to the power supply  110 . 
     In the overall operation, the power supply  110  generates a main power MPW and a standby power STPW. On the other hand, the main board  120  generates a standby voltage of the main board  120  with the main power MPW in a power-on state, and generates the standby voltage of the main board  120  with the standby power STPW in a power-off state. Similarly, the main board  130  also generates a standby voltage of the main board  130  with the main power MPW in the power-on state, and generates the standby voltage of the main board  130  with the standby power STPW in the power-off state. The operating mechanism of the main board  140  is determined accordingly. 
     On the other hand, the main board  150  generates a standby voltage of the main board  150  with the main power MPW in the power-on state, and generates the standby voltage of the main board  150  also with the main power MPW in the power-off state. Thus, as the main board  150  uses the main power MPW to generate the standby voltage in the power-off state, electronic elements that need to be driven in the main board  150  will be completely driven in the power-off state. Conversely, whether the electronic elements that need to be driven in the main boards  120 - 140  in the power-off state are driven completely, the computer system  100  can maintain their basic operating functions through the main board  150 . In other words, the computer system  100  may achieve the goal of maintaining the operating functions in the power-off state without replacing the power supply  110 . 
     In order to make the present embodiment more comprehensible for those skilled in the art, how the main boards  120 - 150  generate the corresponding standby voltages with the power provided by the power supply  110  is further illustrated. 
       FIG. 2  is a schematic circuit block diagram of the main board driven by the power supply according to an embodiment of the present invention. Referring to  FIG. 2 , the main board  120  includes a controller  121 , a switch  122 , a voltage converter  123 , and a voltage converter  124 . The controller  121  is electrically connected to the power supply  110 . The switch  122  is electrically connected to the power supply  110  and the controller  121 . The voltage converter  123  is electrically connected to the controller  121 , and the voltage converter  124  is electrically connected to the switch  122 . 
     In the overall operation, the controller  121  receives a model identification code ID 2 . It should be noted that, as shown in  FIG. 3 , the main boards  120 - 150  each has an identification code. For example, an identification code of the main board  120  is {00}, an identification code of the main board  130  is {01}, an identification code of the main board  140  is {10}, and an identification code of the main board  150  is {11}. Hence, when the controller  121  receives the model identification code ID 2 , the controller  121  compares the model identification code ID 2  with the identification code {00} of the main board  120  to determine whether a corresponding operation is to be performed. 
     When the model identification code ID 2  conforms to the identification code {00} of the main board  120 , the controller  121  then outputs a power enable signal PS_ON_ 2  to the power supply  110 , and outputs a standby voltage startup signal ST_ON_ 2  to the switch  122 . On the other hand, when the power of the main board  120  is on and the power supply  110  receives the power enable signal PS_ON_ 2 , the power supply  110  then outputs the main power MPW to the main board  120 . 
     It should be noted that the controller  121  switches the level of the standby voltage startup signal ST_ON_ 2  according to a voltage control signal CT 2  in a power-on state. Therefore, the switch  122  outputs the main power MPW in the power-on state such that the voltage converter  124  converts the main power MPW from the switch  122  to a standby voltage V 22  of the main board  120 . Conversely, the switch  122  will output the standby power STPW in the power-off state so that the voltage converter  124  converts the standby power STPW to the standby voltage V 22  of the main board  120 . In other words, the main board  120  generates the standby voltage V 22  with the main power MPW provided by the power supply  110  in the power-on state. On the contrary, the main board  120  generates the standby voltage V 22  with the standby power STPW provided by the power supply  110  in the power-off state. 
     In the meanwhile, when the power supply  110  receives the power enable signal PS_ON_ 2 , it also outputs a main voltage startup signal M_ON_ 2  to the controller  121 . Here, the controller  121  shields the main voltage startup signal M_ON_ 2  in the power-off state such that the voltage converter  123  can not generate a main voltage V 21 . Contrarily, the controller  121  in the power-on state transmits the main voltage startup signal M_ON_ 2  to the voltage converter  123  according to the voltage control signal CT 2 . At this time, the voltage converter  123  generates the main voltage V 21  according to the main voltage startup signal M_ON_ 2 . 
     Notably, the main board  120  further includes a south bridge chip  125  in the embodiment of  FIG. 2 . Here, the south bridge chip  125  generates the voltage control signal CT 2  received by the controller  121 . Moreover, the controller  121  described in the present embodiment is, for example, a complex programmable logic device. In addition, the internal configurations and the operating mechanisms of the main boards  130  and  140  are all identical to that of the main board  120  and thus not repeated herein. 
     On the other hand,  FIG. 4  shows a schematic circuit block diagram of a main board driven by a power supply according to another embodiment of the present invention. Referring to  FIG. 4 , the main board  150  includes a controller  151 , a switch  152 , a voltage converter  153 , a voltage converter  154 , and a south bridge chip  155 . Here, the internal configuration of the main board  150  is substantially identical to the internal configurations of the main boards  120 - 140 . Moreover, the operating mechanism of the main board  150  is also similar to the operating mechanisms of the main boards  120 - 140 . 
     Herein, the controller  151  receives a model identification code ID 5  and outputs a standby voltage startup signal ST_ON_ 5  and a power enable signal PS_ON_ 5  when the model identification code ID 5  conforms to the identification code {11} of the main board  150  corresponding to the controller  151 . Accordingly, the power supply  110  outputs a main power MPW and a main voltage startup signal M_ON_ 5  to the main board  150 . The switch  152  receives the main power MPW and a standby power STPW, and determines the power outputted based on the standby voltage startup signal ST_ON_ 5 . The voltage converter  154  then converts the power from the switch  152  to a standby voltage V 52 . The voltage converter  153  generates a main voltage V 51  according to the main voltage startup signal M_ON_ 5 . The south bridge  155  then generates a voltage control signal CT 5  needed by the controller  151 . 
     However, the difference in the operating mechanisms between the main board  150  and the main boards  120 - 140  is that the controller  151  does not switch the level of the standby voltage startup signal ST_ON_ 5  in the power-on state. Therefore, the switch  152  outputs the main power MPW in the power-on state such that the voltage converter  154  converts the main power MPW from the switch  152  to the standby voltage V 52  of the main board  150 . Similarly, the switch  152  also outputs the main power MPW in the power-off state so that the voltage converter  154  converts the main power MPW to the standby voltage V 52  of the main board  150 . The detailed operation of the embodiment in  FIG. 4  is included in the embodiments aforementioned and thus not repeated herein. 
     In summary, the present invention applies a method of generating the standby voltage of the main board using the main power of the computer system to elevate the operating functions of the computer system when the main board is in the power-on and the power-off states. Therefore, to the main board that uses the main power to generate the standby voltage, the electronic elements needed to be driven in the main board will be completely driven in the power-off state and thereby allow the computer system to achieve the required operating functions without replacing the power supply. 
     Although the present invention has been described with reference to the above embodiments, it will be apparent to one of the ordinary skill in the art that modifications to the described embodiment may be made without departing from the spirit of the invention. Accordingly, the scope of the invention will be defined by the attached claims not by the above detailed descriptions.