Abstract:
A power converter includes an inductor, first through fourth switches, and a control device. The first switch is coupled between a first end of the inductor and ground, the second switch is coupled between an input end and a second end of the inductor, the third switch is coupled between the first end of the inductor and a first output end, and the fourth switch is coupled between the second end of the inductor and a second output end. The control device charges the inductor by turning on the first and second switches. Based on output voltages of the first and second output ends, the control device determines whether the first and second output ends are to be charged or discharged. The second and third switches are turned on for charging the first output end, or the first and fourth switches are turned on for discharging the second output end.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/821,577, filed on Aug. 07, 2006 and entitled “Multiple Voltage Output Power Converter,” the contents of which are incorporated herein by reference. 
     
     BACKGROUND OF THE INVENTION  
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a power converter and related method, and more particularly, to a power converter and related method capable of providing multiple output voltages. 
         [0004]    2. Description of the Prior Art 
         [0005]    In general, an electronic device is composed of a variety of units. Each unit may be operated under a unique voltage level. Therefore, the electronic device must include a power converter for stably generating expected voltage levels. According to different requirements, there are different types of power converters, and many of the converters are derived from step down (Buck) converters and step up (Boost) converters. A step down converter reduces direct-current (DC) voltage of an input end to a predefined voltage level, while a step up power converters raises DC voltage of an input end to a predefined voltage level. 
       SUMMARY OF THE INVENTION  
       [0006]    It is therefore a primary objective of the claimed invention to provide a power converter and related method capable of providing multiple output voltages. 
         [0007]    The present invention discloses a power converter capable of providing multiple output voltages. The power converter comprises an input end for receiving an input voltage, a plurality of output ends for providing a plurality of output voltages, an inductor, a first switch coupled between a first end of the inductor and a predefined voltage with a voltage level lower than a voltage level of the input voltage, a second switch coupled between the input end and a second end of the inductor, a third switch coupled between the first end of the inductor and a first output end of a plurality of output ends, a fourth switch coupled between the second end of the inductor and a second output end of the plurality of output ends, and a control device for turning on the first switch and the second switch to charge the inductor, determining whether the first output end and the second output end are needed to be charged according to a first output voltage received from the first output end and a second output voltage received from the second output end, and turning on the second switch and the third switch to discharge the inductor through the first end of the inductor and charge the first output end, or turning on the first switch and the fourth switch to discharge the inductor through the first end of the inductor and discharge the second output end through the second end of the inductor, according to the determination result. 
         [0008]    The present invention further discloses a method for providing multiple output voltages. The method comprises providing a first power source and a second power source with a level lower than a level of the first power source, providing a first path between a first end of an inductor and the first power source and providing a second path between a second end of the inductor and the second power source, so as to make current flow from the first power source through the first path, the inductor, and the second path to the second power source sequentially, for charging the inductor, determining whether a first output end is needed to be charged according to a first output voltage received from the first output end, providing the first path between the first end of the inductor and the first power source and providing a third path between the second end of the inductor and the first output end when the first output end is needed to be charged, so as to make current flow from the inductor through the third path to the first output end, for charging the first output end, determining whether a second output end is needed to be discharged according to a second output voltage received from the second output end, and providing a fourth path between the first end of the inductor and the second output end and providing the second path between the second end of the inductor and the second power source when the second output end is needed to be discharged, so as to make current flow from the second output end through the fourth path to the inductor, for discharging the second output end. 
         [0009]    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 that is illustrated in the various figures and drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0010]      FIG. 1  illustrates a schematic diagram of a power converter capable of providing multiple output voltages according to a first embodiment of the present invention. 
           [0011]      FIG. 2  illustrates a flow chart of operations of the power converter shown in  FIG. 1 . 
           [0012]      FIG. 3  illustrates an equivalent circuit diagram of a power converter. 
           [0013]      FIG. 4  illustrates an equivalent circuit diagram of a power converter. 
           [0014]      FIG. 5  illustrates an equivalent circuit diagram of a power converter. 
           [0015]      FIG. 6  illustrates a schematic diagram of a power converter capable of providing multiple output voltages according to a second embodiment of the present invention. 
           [0016]      FIG. 7  illustrates a flow chart of operations of the power converter shown in  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION  
       [0017]    Please refer to  FIG. 1 .  FIG. 1  illustrates a schematic diagram of a power converter  10  capable of providing multiple voltages according to a first embodiment of the present invention. The power converter  10  comprises a comparison circuit  12 , a logic circuit  14 , an inductor L, a plurality of switches SW H0 ˜SW Hm  and SW L0 ˜SW Ln , and a plurality of driving units D H0 ˜D Hm  and D L0 ˜D Ln . The power converter  10  comprises an input end, m number of output ends O H1 ˜O Hm  and n number of output ends O L1 ˜O Ln . A voltage level of the input end is represented by V IN , and voltage levels of the output ends O H1 ˜O Hm  and O L1 ˜O Ln  are respectively represented by V GH1 ˜V GHm  and V GL1 ˜V GLn . The inductor L comprises a first end and a second end respectively coupled to a ground and the input end of the power converter  10  through the switches SW H0  and SW L0 . Each of the switches SW H1 ˜SW Hm  is coupled between one of the output ends O H1 ˜O Hm  and the first end of the inductor, and each of the switches SW L1 ˜SW Ln  is coupled between one of the output ends O L1 ˜O Ln  and the second end of the inductor. The comparison circuit  12  is coupled to the input end of the power converter  10 , and compares values of the output voltages V GH1 ˜V GHm  and V GL1 ˜V GLn  with predefined voltages. Then, the logical circuit  14  controls the driving units D H0 ˜D Hm  and D L0 ˜D Ln  according to the comparison results provided by the comparison circuit  12 . The driving units D H0 ˜D Hm  provide control signals for turning on (forming short circuit) or turning off (forming open circuit) the switches SW H0 ˜SW Hm , while the driving units D L0 ˜D Ln  provide control signals for turning on or turning off the switches SW L0 ˜SW Ln . 
         [0018]    In the power converter  10  of the first embodiment of the present invention, the input voltage V IN  can be upgraded to the output voltages V GH1 ˜V GHm  or reduced to the output voltages V GL1 ˜V GLn . That is, according to different requirements, the power converter  10  transforms the input voltage V IN  into the output voltages with the (m+n) number of voltage levels. For example, if the output voltages V GL1  and V GH1  are to be provided, a flow chart of operations of the power converter  10  is illustrated in  FIG. 2 , and comprises following steps: 
         [0019]    Step  100 : Start. 
         [0020]    Step  110 : Turn on the switches SW H0  and SW L0 , and turn off the switches SW H1 ˜SW Hm  and SW L1 SW   Ln . 
         [0021]    Step  120 : Determine whether the voltage level of the output end O H  reaches V GH1 ; if true, execute step  140 ; if false, execute step  130 . 
         [0022]    Step  130 : Turn on the switches SW L0  and SW H1 , and turn off the switches SW H0 , SW H2 ˜SW Hm , and S WL1 ˜SW Ln , and execute step  110 . 
         [0023]    Step  140 : Determine whether the voltage level of the output end O L1  reaches V GL1 ; if true, execute step  160 ; if false, execute step  150 . 
         [0024]    Step  150 : Turn on the switches SW H0  and SW L1 , and turn off the switches SW H1 ˜SW Hm , SW L0 , and SW L2 ˜SW Ln , and execute step  110 . 
         [0025]    Step  160 : Turn off the switches SW H0 ˜SW Hm  and SW L0 ˜SW Ln . 
         [0026]    In the flow chart shown in  FIG. 2 , when turning on the switches SW H0  and SW L0  and turning off other switches in the step  110 , the power converter  10  charges the inductor L. When the voltage level of the output end O H1  in the step  110  does not reach V GH1 , the step  130  is executed for turning on the switches SW L0  and SW H1  and turning off other switches, so that the power converter  10  discharges the inductor L and charges the output end O H1  until the voltage level of the output end O H1  reaches V GH1 . Similarly, in the step  140 , when the voltage level of the output end O L1  does not reach V GL1 , the step  150  is executed for turning on the switches SW H0  and SW L1  and turning off other switches, so that the power converter  10  discharges the inductor L and charges the output end O L1  until the voltage level of the output end O L1  reaches V GL1 . Please refer to  FIG. 3  to  FIG. 5 .  FIG. 3  illustrates an equivalent circuit diagram of the power converter  10  after executing the step  110 ,  FIG. 4  illustrates an equivalent circuit diagram of the power converter  10  after executing the step  130 , and  FIG. 5  illustrates an equivalent circuit diagram of the power converter  10  after executing the step  150 . From  FIG. 3  to  FIG. 5 , arrows represent current directions. 
         [0027]    Please refer to  FIG. 6 .  FIG. 6  illustrates a schematic diagram of a power converter  20  capable of providing multiple output voltages according to a second embodiment of the present invention. The power converter  20  comprises a comparison circuit  22 , a logical circuit  24 , a current limitation unit  26 , an inductor L, a plurality of switches SW H0 ˜SW Hm  and SW L0 ˜SW Ln , and a plurality of driving units D H0 ˜D Hm  and D L0 ˜D Ln . The power converter  20  comprises an input end, m number of output ends O H1 ˜O Hm , and n number of output ends O L1 ˜O Ln . A voltage level of the input end is represented by V IN , and voltage levels of the output ends O H1 ˜O Hm  and O L1 ˜O Ln  are respectively represented by V GH1 ˜V GHm  and V GL1 ˜V GLn . A first end of the inductor L is coupled to a ground voltage through the switch SW H0 , and a second end of the inductor L is coupled to the input end of the power converter  20  through the switch SW L0  and the current limitation unit  26 . Each of the switches SW H1 ˜SW Hm  is coupled between one of the output ends O H1 ˜O Hm  and the first end of the inductor L, and each of the switches SW L1 ˜SW Ln  is coupled between one of the output ends O L1 ˜O Ln  and the second end of the inductor L. In the power converter  20 , the current limitation unit  26  comprises a resistance R. A cross voltage of the resistance R is represented by V SENSE . The comparison circuit  22  is coupled to the input end of the power converter  20 , and compares the values of the output voltages V GH1 ˜V GHm  and V GL1 ˜V GLn  with predefined voltage levels. Then, the logical circuit  24  controls the driving units D H0 ˜D Hm  and D L0 ˜D Ln  according to the comparison results provided by the comparison circuit  22  and the cross voltage V SENSE . The driving units D H0 ˜D Hm  provide control signals for switching the switches SW H0 ˜SW Hm , and the driving units D H0 ˜D Hn  provide control signals for switching the switches SW L0 ˜SW Ln . 
         [0028]    Comparing to the power converter  10  of the first embodiment of the present invention, the power converter  20  of the second embodiment of the present invention is also capable of transforming the input voltage V IN  into the output voltages with (m+n) voltage levels. The difference between them is that the power converter  20  comprises the current limitation device  26 . The power converter  20  controls current flowing through the inductor L according to the cross voltage V SENSE  of the current limitation unit  26 . For example, if the output voltages V GL1  and V GH1  are to be provided, a flow chart of operation of the power converter  20  is illustrated in  FIG. 7 , and comprises following steps: 
         [0029]    Step  200 : Start. 
         [0030]    Step  205 : Determine whether the cross voltage V SENSE  is greater than a predefined value; if true, execute step  220 ; if false, execute step  210 . 
         [0031]    Step  210 : Turn on the switches SW H0  and SW L0 , and turn off the switches SW H1 ˜SW Hm  and SW L1 ˜SW Ln , and execute step  205 . 
         [0032]    Step  220 : Determine whether the voltage level of the output end O H1  reaches V GH1 ; if true, execute step  240 ; if false, execute step  230 . 
         [0033]    Step  230 : Turn on the switches SW L0  and SW H1 , and turn off the switches SW H0 , SW H2 ˜SW Hm  and SW L1 ˜SW Ln , and execute step  205 . 
         [0034]    Step  240 : Determine whether the voltage level of the output end O L1 , reaches V GL1 , if true, execute step  260 ; if false, execute step  250 . 
         [0035]    Step  250 : Turn on the switches SW H0  and SW L1 , turn off the switches SW H1 ˜SW Hm , SW L0  and SW L2 ˜SW Ln , and execute step  205 . 
         [0036]    Step  260 : Turn off the switches SW H0 ˜SW Hm  and SW L0 ˜SW Ln . 
         [0037]    In the flow chart of  FIG. 7 , the step  205  first determines whether the cross voltage V SENSE  of the current limitation device  26  is greater than the predefined value. If the cross voltage V SENSE  is not greater than the predefined value, the step  210  is executed for turning on the switches SW H0  and SW L0  and turning off other switches, so that the power converter  20  charges the inductor L. If the cross voltage V SENSE  is greater than the predefined value, the step  220  is executed for determining whether the voltage level of the output end O H1  reaches V GH1 , and the step  240  is executed for determining whether the voltage level of the output end O L1  reaches V GL1 . In the step  220 , if the voltage level of the output end O H1  does not reach V GH1 , the step  230  is executed for turning on the switches SW L0  and SW H1  and turning off other switches, so that the power converter  20  discharges the inductor L and charges the output end O H1  until the voltage level of the output end O H1  reaches V GH1 . Similarly, in the step  240 , when the voltage level of the output end O L1  does not reach V GL1 , the step  250  is executed for turning on the switches SW H0  and SW L1  and turning off other switches, so that the power converter  20  discharges the inductor L and charges the output end O L1  until the voltage level of the output end O L1  reaches V GL1 . Please refer to  FIG. 3  to  FIG. 5  again.  FIG. 3  similarly illustrates an equivalent circuit diagram of the power converter  20  after executing the step  210 ,  FIG. 4  similarly illustrates an equivalent circuit diagram of the power converter  20  after executing the step  230 , and  FIG. 5  similarly illustrates an equivalent circuit diagram of the power converter  20  after executing the step  250 . 
         [0038]    In summary, according to different requirements, the power converter of the present invention is capable of transforming an input voltage into a plurality of output voltages with different voltage levels and determining to charge and discharge according to output voltage levels of the output ends, so as to effectively reduce or boost input voltages. 
         [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.