Abstract:
A voltage adaptor card. The voltage adaptor card, inserted into a motherboard having first slots to provide a first voltage source, includes second slots, a plurality of pins for inserting into the first slots, and a voltage converter having an input terminal and an output terminal. The input terminal is coupled to the first voltage source through the plurality of pins. The output terminal is coupled to the second slots and outputs a second voltage source.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a voltage adaptor card for a motherboard, and particularly to a voltage adaptor card which provides required voltage through slots.  
           [0003]    2. Description of the Related Art  
           [0004]    Owing to low power requirement and progress in semiconductor fabrication, operating voltages of most integrated circuits are reduced, as are most PCI interface cards. Because PCI slots on motherboards compliant with only the outdated PCI spec only provide 5V voltage without 3.3V voltage, either the motherboard compliant with only the outdated PCI spec or the PCI card itself must be modified to provide both 5V and 3.3V voltages.  
           [0005]    To avoid modification of motherboards compliant with only the outdated PCI spec or PCI interface card, there is a need for a voltage adaptor card which provides required voltages.  
         SUMMARY OF THE INVENTION  
         [0006]    It is therefore an object of the present invention to provide a motherboard with a single voltage source, providing various voltage sources required by interface cards.  
           [0007]    To achieve the above objects, the present invention discloses a voltage adaptor card to adapt voltage supplied from the motherboard to that suitable for interface cards.  
           [0008]    The voltage adaptor card in the present invention includes a voltage converter, PCI slots, and pins. The voltage converter includes a regulator and an adjustment circuit. The PCI slots provide 5V voltage. An output of the regulator provides interface cards inserted in the PCI slots  25  with 3.3V voltage.  
           [0009]    The regulator has an input terminal, an adjustment terminal, and an output terminal. The input terminal of the regulator is coupled to the first voltage source through the pins.  
           [0010]    The adjustment circuit has an input terminal and an output terminal. The input terminal of the adjustment circuit is coupled to the output terminal of the regulator. The output terminal of the adjustment circuit is coupled to the adjustment terminal of the regulator.  
           [0011]    The adjustment circuit is implemented by a first resistor and a second resistor. The first resistor is coupled between the input terminal of the adjustment circuit and the output terminal of the adjustment circuit. A second resistor is coupled between the output terminal of the adjustment circuit and a ground potential. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The aforementioned objects, features and advantages of this invention will become apparent by referring to the following detailed description of the preferred embodiment with reference to the accompanying drawings, wherein:  
         [0013]    [0013]FIG. 1 is a block diagram of the present invention.  
         [0014]    [0014]FIG. 2 is a block diagram of the voltage converter.  
         [0015]    [0015]FIG. 3 shows a table of output voltages selected by the dip switch.  
         [0016]    [0016]FIG. 4 shows a pin assignment of PCI slots.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    [0017]FIG. 1 is a block diagram of the present invention. PCI slots  10  and a voltage adaptor card  20  are shown in FIG. 1. The voltage adaptor card  20  includes a voltage converter  200 , PCI slots  25 , and pins  27 . The voltage converter  200  includes a regulator  21  and an adjustment circuit  23 . The PCI slots  10  provide 5V voltage. An output Vout of the regulator  21  provides interface cards inserted in the PCI slots  25  with 3.3V voltage.  
         [0018]    FIG. 2  is a block diagram of the voltage converter. The voltage converter  200  includes a regulator  21 , resistors R 1 , R 2 , dip switch  32 , resistors R 11 , R 12 , R 13 , and variable resistor R 14 . The dip switch  32  is used for selecting resistors R 11 , R 12 , R 13 , and variable resistor R 14 . The regulator  21  is a linear regulator having three terminals, an input terminal Vin, an adjustment terminal Adj, and an output terminal Vout. The resistors R 1 , R 2 , dip switch  32 , and resistor R 3  forms an adjustment circuit  23 , a feedback circuit. A junction of the resistors R 1  and R 2  is coupled to the adjustment terminal Adj of the regulator  21 . The voltage of the output terminal Vout is determined by a reference voltage Vref from the regulator  21 , a ratio of the resistors R 2  and R 1 , a ratio of the resistors R 3 , selected by the dip switch  32 , and R 1 , and a product of the adjust current Iadj and resistors R 2 , R 3 . 
         Vout=Vref(1+( R   2 + R   3 )/ R   1 )+ I adj*( R   2 + R   3 ) 
         [0019]    A capacitor C 1  is used for frequency compensation and stabilizing the regulator  21 .  
         [0020]    [0020]FIG. 3 shows a table of output voltages selected by the dip switch. The dip switch  32  includes four switches S 1 , S 2 , S 3 , and S 4 . As shown in FIG. 3, when the switch S 1  is turned on and the others are turned off, the dip switch  32  selects the resistor R 11  coupled to the resistor R 2 , thus the output terminal Vout of the regulator  21  has a voltage about 3V. When the switch S 2  is turned on and the others are turned off, the dip switch  32  selects the resistor R 12  coupled to the resistor R 2 , thus the output terminal Vout of the regulator  21  has a voltage about 3.3V. When the switch S 3  is turned on and the others are turned off, the dip switch  32  selects the resistor R 13  coupled to the resistor R 2 , thus the output terminal Vout of the regulator  21  has a voltage about 3.6V. When the switch S 4  is turned on and the others are turned off, the dip switch  32  selects the variable resistor R 14  coupled to the resistor R 2  thereby adjusting the output terminal Vout of the regulator  21 . The resistors R 11 , R 12 , and R 13  are used for coarse tuning, and the variable resistor R 14  for fine tuning.  
         [0021]    [0021]FIG. 4 is a block diagram of PCI slots. As shown in FIG. 4, both the PCI slots  10  and the PCI slots  25  have pins A 11 , A 15 , A 17 , A 19 , a 21 , A 23 , and A 25 , assigned for 5V by the outdated PCI spec, and unused pins B 11 , B 15 , B 17 , B 19 , B 21 , B 23 , B 25 , and B 29 . The unused pins B 11 , B 15 , B 17 , B 19 , B 21 , B 23 , B 25 , and B 29  are assigned for 3.3V by new PCI spec. The PCI slots  10  are located in the motherboard  300 , providing only 5V voltage. When the pins  27  on the voltage adaptor card  20  are inserted into the PCI slots  10  on the motherboard  300 , 5V voltage is supplied to the voltage converter  200  through pins A 11 , A 15 , A 17 , A 19 , a 21 , A 23 , and A 25  of the pins  27 . The output terminal of the voltage converter  200  is coupled to the unused pins B 11 , B 15 , B 17 , B 19 , B 21 , B 23 , B 25 , and B 29  to provide 3.3V voltage and satisfying pin assignments of the new PCI spec.  
         [0022]    The voltage adaptor card has the following advantages.  
         [0023]    (1) The voltage converter adapts voltage to that required for PCI slots from the motherboard, for broader application.  
         [0024]    (2) The voltage of the PCI slots is adjusted by feedback resistors thereby testing interface cards on the PCI slots. The motherboards providing single voltage can continue to be used without modification.  
         [0025]    Although the present invention has been described in its preferred embodiments, it is not intended to limit the invention to the precise embodiments disclosed herein. Those who are skilled in this technology can still make various alterations and modifications without departing from the scope and spirit of this invention. Therefore, the scope of the present invention shall be defined and protected by the following claims and their equivalents.