Abstract:
An exemplary motherboard includes a driving module, at least two first slots arranged for mounting two first type of memories, at least two second slots arranged for mounting two second type of memories, and a voltage regulator. The driving module is electronically connected to the at least two first slots, the at least two second slots, and the voltage regulator in turn via a channel. The first type of memories and the second type of memories are alternatively mounted on the motherboard, the voltage regulator detects which type memory is currently mounted on the motherboard and outputs voltages suitable for the type of memory mounted on the motherboard accordingly.

Description:
CROSS-REFERENCES TO RELATED APPLICATION 
       [0001]    Relevant subject matter is disclosed in a co-pending U.S. patent application with application Ser. No. 11/766,105, filed on Jun. 21, 2007, and entitled “MOTHERBOARD”, which is assigned to the same assignee as this patent application. 
     
    
     BACKGROUND  
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to motherboards, and particularly to a motherboard for supporting different types of memories. 
         [0004]    2. Description of Related Art 
         [0005]    Currently, a typical personal computer comprises a motherboard, interface cards, and peripheral accessories. The motherboard is the heart of the personal computer. On the motherboard, in addition to the central processing unit (CPU), the chip set, and the slots for installing the interface cards, it further includes memory module slots for installing memory modules. 
         [0006]    Due to constant change in the computer industry, memories used in the computer have changed from DDR2 (Double Data Ram II) used in the past to higher speed memories such as DDR3 (Double Data Ram III). 
         [0007]    Because DDR2 is cheaper than DDR3, the main board with DDR2 still is in demand in the market. The difference in operating DDR2 and DDR3 includes: DDR2 utilizes 1.8V VDD and 0.9V VTT, while DDR3 utilizes 1.5V VDD and 0.75V VTT. Currently, no motherboard is compatible with both DDR3 and DDR2. As a result, more motherboards have to be fabricated adding to production cost. 
         [0008]    What is needed is to provide a motherboard capable of flexibly supporting different types of memories. 
       SUMMARY 
       [0009]    An exemplary motherboard includes a driving module, at least two first slots arranged for mounting two first type of memories, at least two second slots arranged for mounting two second type of memories, and a voltage regulator. The driving module is electronically connected to the at least two first slots, the at least two second slots, and the voltage regulator in turn via a channel. The first type of memories and the second type of memories are alternatively mounted on the motherboard, the voltage regulator detects which type memory is currently mounted on the motherboard and outputs voltages suitable for the type of memory mounted on the motherboard accordingly. 
         [0010]    Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic view of a motherboard for supporting different types of memories in accordance with a first embodiment of the present invention having four slots and a voltage regulator; 
           [0012]      FIG. 2  is a schematic view of a motherboard for supporting different types of memories in accordance with a second embodiment of the present invention having four slots and a voltage regulator; and 
           [0013]      FIG. 3  is a circuit diagram of the voltage regulator of  FIG. 1  and  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to  FIG. 1 , a motherboard for supporting different types of memories in accordance with a first embodiment of the present invention includes a driving module  50  such as a north bridge chipset, two DDR2 slots  10 ,  20 , two DDR3 slots  30 ,  40  and a voltage regulator  200 , arranged in that order. The DDR2 slots  10 ,  20  are used for installing two first type of memories, such as two DDR2 memories. The DDR3 slots  30 ,  40  are used for installing two second type of memories, such as two DDR3 memories. The north bridge chipset  50  is connected to the two DDR2 slots  10 ,  20 , the two DDR3 slots  30 ,  40 , and the voltage regulator  200  in turn via a channel A. 
         [0015]    Referring to  FIG. 2 , a motherboard for supporting different types of memories in accordance with a second embodiment of the present invention includes a north bridge chipset  100 , two DDR3 slots  60 ,  70 , and two DDR2 slots  80 ,  90  and a voltage regulator  200 , arranged in that order. The DDR3 slots  60 ,  70  are used for installing two second type of memories, such as two DDR3 memories. The DDR2 slots  80 ,  90  are used for installing two first type of memories, such as two DDR2 memories. The north bridge chipset  100  is connected to the two DDR3 slots  60 ,  70 , the two DDR2 slots  80 ,  90 , and the voltage regulator  200  in turn via a channel B. 
         [0016]    The first type of memories and the second type of memories are alternatively mounted on the motherboard. The voltage regulator  200  provides working voltage for the DDR2 slots or the DDR3 slots according to different types of memories mounted on the motherboard. In the practice, the DDR2 slots and the DDR3 slots may be arranged in a plurality ways. The signal rise time is indicated for each possible arrangement along with an indication of having non-monotonic characteristic or not in the table below: 
         [0000]                                                    Slotsarraymanner                                                                                                                                                                                                       Signal rise   0.667   1.159   0.616   1.150   0.716   0.597       time(ns)       Non-monotonic   No   Yes   Yes   No   Yes   No                    
According to the table, the direction of the arrowhead represents the alignment order of the DDR2 and DDR3 slots. The signal rise times using the motherboards in accordance with the first and second embodiments of the present invention are respectively 0.667 ns and 0.597 ns, and do not have a non-monotonic characteristic during signal transmission, so the two embodiments are the two optimal choice.
 
         [0017]    Referring to  FIG. 3 , the voltage regulator  200  comprises a controller  12  having a feedback terminal and an output terminal, a filter  14  having an input terminal and an output terminal, a linear voltage regulator  16 , and a feedback circuit  18 . The output of the controller  12  is connected to the input terminal of the filter  14 , and the filter  14  outputs a VDD voltage at the output terminal thereof. The VDD voltage is transmitted to the linear voltage regulator  16 , and is converted into a VTT voltage transmitted to the DDR2 slots and the DDR3 slots. The output terminal of the filter  14  is connected to the DDR2 slots and the DDR3 slots to provide the VDD voltage. 
         [0018]    The feedback circuit  18  comprises two transistors Q 1  and Q 2 , four resistors R 1 ˜R 4 , and a feedback resistor R 5 . The transistors Q 1  and Q 2  are PMOS transistors. The gate of the transistor Q 1  is connected to ground terminals of the DDR2 slots and to a 5V power source via the resister R 1 . The source of the transistor Q 1  is grounded. The drain of the transistor Q 1  is connected to the  5 V power source via the resistor Q 2  and to the gate of the transistor Q 2 . The gate of the transistor Q 2  is connected to ground terminals of the DDR3 slots. The source of the transistor Q 2  is grounded. The drain of the transistor Q 2  is grounded via the resistors R 3  and R 4  in turn and also connected to the feedback terminal of the controller  12  via the resistor R 3 . The feed back resistor R 5  is connected between the output terminal of the filter  14  and the feedback terminal of the controller  12 . The resistances of the resistors R 1 ˜R 4  are approximately 4.7 Kohms, 4.7 Kohms, 2.4 Kohms, and 1.2 Kohms respectively, and the resistance of the feedback resistor R 5  is approximately 1.1 Kohms. The operation of the feedback circuit  18  is premised upon the fact that the level of the feedback voltage Vfb is stable, in this preferred embodiment, the level of the feedback voltage Vfb is 0.78V. 
         [0019]    When the DDR2 memories are mounted in the DDR2 slots, the DDR3 slots are idle. The ground terminals of the DDR2 slots generate a ground signal. The transistor Q 1  is turned on, and the transistor Q 2  is turned off. According to the following formula: VDD=Vfb*(R 5 +R 4 )/R 4 , the voltage output from the controller  12  is 1.8V. The voltage is provided to the filter  14 , which filters and rectifies the voltage to provide a smooth voltage output. The VDD is provided to the feedback circuit  18  and the DDR2 memories mounted in the DDR2 slots. The linear voltage regulator  16  is configured to receive the VDD voltage and provide a regulated output voltage of VTT (0.9V), which is provided to the DDR2 memories. 
         [0020]    When the DDR3 memories are mounted in the DDR3 slots, the DDR2 slots are idle. The ground terminals of the DDR3 slots generate the ground signal. The transistor Q 1  is turned off, the transistor Q 2  is turned on, and the resistor R 3  is connected in the circuit. According to the following formula: VDD=Vfb*(R 5 +Rx)/Rx, wherein Rx=(R 3 +R 4 )/R 3 *R 4 , the voltage output from the controller  12  is 1.5V. The voltage is provided to the filter  14 , which filters and rectifies the voltage to provide a smooth voltage output. The VDD is provided to the feedback circuit  18  and the DDR3 memories mounted in the DDR3 slots. The linear voltage regulator  16  is configured to receive the VDD voltage and provide a regulated output voltage of VTT (0.75V), which is provided to the DDR3 memories. 
         [0021]    Thus, the motherboard is capable of utilizing either the DDR2 or the DDR3, thus enhancing production capability and reducing production cost. 
         [0022]    The foregoing description of the exemplary embodiments of the invention has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to enable others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein.