Abstract:
A power delivery system delivers a relatively constant voltage to a microprocessor with low inductance and low resistance. The system includes a motherboard, an integrated circuit (IC) mounted on one side of the motherboard, a capacitor bank mounted on the opposite side of the motherboard; and a power converter mounted on the side of the motherboard opposite the IC. The IC contains a microprocessor that receives power from the power converter and capacitor bank. A short electrical path between components is achieved by locating the power converter and the capacitor bank on the side of the motherboard opposite the IC. By shortening the electrical path, the system reduced the inductance and resistance created by the electrical traces. The components of the system are compressed together. Instead of utilizing long traces or specialized parts to connect the power converter to the motherboard, a compressive interface is positioned between the power converter, the capacitor bank and the motherboard. The compressive interface includes conductive materials that facilitate the flow of electricity between the various components. The compressive interface prevents excessive inductance and resistance between the power converter, the capacitor bank, and the motherboard.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    A preferred embodiment of the present invention generally relates to improvements in power delivery to electronic circuits and more particularly relates to an improved power delivery system for microprocessors.  
           [0002]    Current microprocessors and associated integrated circuits typically require higher levels of power as compared to previous microprocessors and integrated circuits. Along with higher power requirements, current microprocessors typically draw higher currents. For example, many microprocessors require approximately 100 amps of current to function properly. Additionally, modem microprocessors switch currents at very fast rates, such as from 0 amps to 100 amps in 1 microsecond or less. Overall, because modem microprocessors operate at high speeds, they typically require greater amounts of power than previously required.  
           [0003]    Typically, microprocessors operate at relatively low voltages, for example 3.3 volts, while continuing to operate at faster speeds. The increased capability and speed of these microprocessors, however, consumes a large amount of power despite the low voltage requirement. The low voltage requirement of current microprocessors typically requires a localized power converter, such as a dc-to-dc converter, to reduce the voltage supplied to the motherboard on which the microprocessor is located. Typically, the power converter is soldered to the motherboard or plugged into the motherboard via a connector. The lower voltage is then conducted through conductors or printed circuit traces on the motherboard to a connector of the component requiring the lower voltage, such as a microprocessor.  
           [0004]    Many power delivery systems and power converters are mounted on a board or module. The module or board is then plugged into a connector on the motherboard. Because the voltage required by the microprocessor is lower, and the power consumption is high, the currents that are supplied to the module become particularly large. Consequently, a low inductance, low resistance path from the power converter to the motherboard is difficult to establish.  
           [0005]    The microprocessor, however, requires a minimum power level to operate. Typically, if the voltage supplied to the microprocessor drops below a certain voltage, the microprocessor does not function properly. Because of the resistance caused by long traces on the motherboard, the voltage at the power converter is typically greater than that supplied to the microprocessor via the traces. Additionally, because the current through the traces switches at a fast rate, the long traces typically yield high inductance. That is, the faster the change in current, the more the voltage at the microprocessor will drop during that change. Fast rates of current change through long traces produce high voltage change. As switching speeds increase, the voltage at the microprocessor decreases. As the voltage at the microprocessor decreases, the performance of the microprocessor decreases.  
           [0006]    A system has been proposed that attempts to address the problems associated with resistance and inductance in integrated circuits and microprocessors by locating the power converter adjacent to the microprocessor. The microprocessor typically includes a receptacle tab that interfaces with a connector located on the power converter. The power converter is connected to the motherboard via another connector that supplies power to the power converter. The power converter then converts the power and supplies the converted power to the microprocessor via the power converter connector. The microprocessor receives the converted power via the receptacle tab.  
           [0007]    However, a suitable motherboard connector is required along with the power converter, and specialized interface components including at least a power converter connector, and a microprocessor receptacle tab. This system is typically more expensive than other systems due to the additional components utilized. Further, this system poses problems when components require maintenance and repair. Because additional, specialized parts and components are used, alternative components typically cannot be substituted when one of the specialized parts breaks. Additionally, the presence of various components may diminish the reliability of the system. Each additional component and part is susceptible to failure. Typically, if one component or part fails, the entire system fails. Therefore, the presence of more components and parts typically increases the risk of system failure.  
           [0008]    A need remains for an improved power delivery apparatus and system for electronic circuits and microprocessors in particular. Further, a need also exists for a less expensive power delivery system. Additionally, a need has long existed for a more reliable power delivery system and for a more readily interchangeable power delivery system.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    At least one preferred embodiment of the present invention relates to a system for providing a relatively constant voltage to a microprocessor with low inductance and low resistance. The system includes a motherboard, an integrated circuit (IC) mounted on one side of the motherboard, a capacitor bank mounted on the opposite side of the motherboard; and a power converter mounted on the side of the motherboard opposite the IC. The IC contains a microprocessor that receives power from the power converter and capacitor bank. A short electrical path between the IC, power converter and capacitor bank is achieved by locating the power converter and the capacitor bank on the side of the motherboard opposite the IC. By shortening the electrical path, the system reduces the inductance and resistance created by the electrical traces.  
           [0010]    The components of the system are compressed together to electrically communicate through a compressive interface. Instead of utilizing long traces or specialized parts to connect the power converter to the motherboard, a compressive interface is utilized between the power converter, capacitor bank and printed circuit board. The compressive interface includes conductive materials that facilitate the flow of electricity between the various components. The compressive interface prevents excessive inductance and resistance between the power converter, the capacitor bank, and the motherboard. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 illustrates an exploded, top view of a power module system formed in accordance with a preferred embodiment of the present invention.  
         [0012]    [0012]FIG. 2 illustrates a top view of a power converter formed in accordance with a preferred embodiment of the present invention.  
         [0013]    [0013]FIG. 3 illustrates an exploded, top view of a power converter formed in accordance with a preferred embodiment of the present invention.  
         [0014]    [0014]FIG. 4 illustrates an exploded, bottom view of a power converter formed in accordance with a preferred embodiment of the present invention.  
         [0015]    [0015]FIG. 5 illustrates a top view of a backer plate formed in accordance with a preferred embodiment of the present invention.  
         [0016]    [0016]FIG. 6 illustrates a bottom view of a backer plate formed in accordance with a preferred embodiment of the present invention. 
     
    
       [0017]    The foregoing summary, as well as the following detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, embodiments which are presently preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentality shown in the attached drawings.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    [0018]FIG. 1 illustrates an exploded, top view of a power module system  100  formed in accordance with a preferred embodiment of the present invention. The power module system  100  includes a power converter  110 , a motherboard  130 , and a heat sink  150  that includes heat sink screws  152  and fastener openings  154  located about the perimeter of the heat sink  150 . The power converter  110  supports the motherboard  130 , which in turn supports the heat sink  150 .  
         [0019]    [0019]FIG. 2 illustrates a top view of the power converter  110  formed in accordance with a preferred embodiment of the present invention. The power converter  110  includes a power converter top surface  112  with heat sink mounting standoffs  114  extending upward therefrom. The standoffs  114  are arranged to align with openings  148  through the motherboard  130  and openings  154  in the heat sink  150 . When assembled, the standoffs  114  threadably engage the heat sink screws  152  to form a compressive connection between the heat sink  150  and the power converter  110 . The power converter  110  also includes a compressive interface  116 , a power connector cover  122 , and side vents  128 . The compressive interface  116  is located on the top surface  112  of the power converter  110  and is compressed flush with the top surface  112  to enable the power converter  110  to compress, or abut substantially flush, against one side of the motherboard  130 . Alternatively, the compressive interface  116  may be counter sunk to reside flush with the top surface  112 . Optionally, the compressive interface  116  may be centered between the mounting standoffs  114  to ensure that an even force is applied to the compressive interface  116 . The compressive interface  116  includes power converter contacts  118  that are aligned, optionally, in rows and columns. The power converter contacts  118  may include input power pins, output power pins, and control input/output lines. The power converter  110  is further described below with respect to FIGS. 3 and 4.  
         [0020]    Referring again to FIG. 1, the motherboard  130  includes a motherboard second side  132 , a motherboard first side  136  and mounting stud openings  148  arranged to align with the mounting standoffs  114 . The motherboard first side  136  includes an integrated circuit (IC) socket  138  that retains an IC  140 . The IC socket  138  includes power supply contacts that may include input and output pins that extend downward from the socket  138  and connect to the motherboard  130  through vias located on the motherboard. Alternatively, the motherboard  130  may include through holes that allow input and output pins from the socket  138  to project from an opposite side of the motherboard  130  (second side  132 ). The IC  140  is secured onto the motherboard via the IC socket  138 . The IC  140  contains a microprocessor (not shown) that may be connected to the circuit board of the IC  140  via a Land Grid Array (LGA), a Pin Grid Array (PGA), a Ball Grid Array (BGA) and the like.  
         [0021]    The IC  140  is connected to the motherboard  130  via the IC socket  138 . Preferably, the IC socket  138  is a compressible piece of plastic with columns of conductive material that provide electrical paths between the IC  140  and the motherboard  130 , such as Tyco Electronic Inc.&#39;s MPI interface. Alternatively, the IC socket  138  may be another compressible material that conducts electricity. Vias located on the motherboard  130  electrically connect the motherboard first side  136  to the motherboard second side  132 . As the IC  140  is connected to the motherboard  130 , the vias, such as plated through vias, extend through the motherboard first side  136  and connect to pads on the motherboard second side  132 . The pads on the motherboard second side  132  are positioned to line up with the compressive interface  116  of the power converter  110 .  
         [0022]    Alternatively, once the IC  140  is connected to the motherboard  130  via the IC socket  138 , power supply contacts of the IC  140  may be received by the compressive interface  116  of the power converter  110 . As the IC  140  is connected to the motherboard  130 , the power supply contacts of the IC  140  extend through the motherboard first side  136  and project from the motherboard second side  132 . Because the power supply contacts extend out from the motherboard second side  132 , the power supply contacts are capable of being received by the compressive interface  116  of the power converter  110 .  
         [0023]    The motherboard  130  is mounted on top of the power converter  110 . The mounting stud openings  148  of the motherboard  130  allow the motherboard second side  132  to compress the compressive interface  116  against the power converter top surface  112 . As the motherboard second side  132  comes into contact with the compressive interface  116  and compresses against the power converter top surface  112 , the compression electrically connects the motherboard second side  132  to the power converter top surface  112 . The power converter contacts  118  of the compressive of the compressive interface  116  are aligned to pads on the motherboard second side  132  and pads on the power converter top surface  112 . Alternatively, the power converter contacts  118  of the compressive interface  116  may be formed to align with, and accept, power supply contacts located on the IC  140 . Preferably, the compressive interface  116  is a compressible plastic with columns of conductive material that provide an electrical path between the power converter  110  and the motherboard. Alternatively, the compressive interface  116  may be another compressive-type interface such as a shorting-v contact or a micro-spring™ contact.  
         [0024]    Once the motherboard  130  is connected to the power converter  110 , the heat sink  150  is placed on top of the IC  140 . The fastener openings  154  of the heat sink  154  allow the heat sink  150  to slide down the heat sink mounting standoffs  114  and come into direct contact with the IC  140 . After the heat sink  150  is positioned on the IC  140 , the heat sink  150  is mounted via the heat sink screws  152 . The heat sink screws  152  are received by the heat sink mounting standoffs  114  which extend toward the heat sink  150  through the motherboard  130  via the mounting stud openings  148  and into the heat sink via the fastener openings  154 . After the heat sink  150  has been positioned on the IC  140 , which is in turn positioned on the power converter  110 , the heat sink screws  152  are positioned over the fastener openings  154  and onto the heat sink mounting standoffs  114 . The heat sink screws  152  threadably fasten the heat sink  150  to the IC  140 . Because the heat sink mounting standoffs  114  are positioned on the power converter top surface  112 , fastening the heat sink  150  to the heat sink mounting standoffs  114  compresses the heat sink  150  and the power converter  110  together while also compressing the IC  140  and the IC socket  138  together. The motherboard  130  is compressed between the heat sink  150  and the power converter  110 . That is, the motherboard second side  132  is compressed into the heat sink  150  while the motherboard first side  136  is compressed into the power converter top side  112 .  
         [0025]    In operation, the power converter  110  receives power from a power supply (not shown) at a first D.C. voltage. The power converter  110  receives the first D.C. voltage through the compressive interface  116 . The power converter  110  converts the first D.C. voltage to a second D.C. voltage which is provided to the IC  140  through the compressive interface  116 . That is, the power converter contacts  118  of the compressive interface  116  transfer the second D.C. voltage to the adjoining power supply contacts  142  of the IC  140 . The heat sink  150  receives the excess heat produced by the IC  140 .  
         [0026]    The location of the power converter  110  in relation to the IC  140  provides a short electrical path between the power converter  110  and the IC  140 . The short electrical path between the power converter  110  and the IC  140  provides power to the microprocessor located in the IC  140  at high current with low inductance and low resistance.  
         [0027]    [0027]FIG. 3 illustrates an exploded, top view of a power converter  110  formed in accordance with a preferred embodiment of the present invention. The power converter  110  includes a cover  122  having cover holes  304 , a main printed circuit board  310 , a backer plate  330 , a capacitor printed circuit board  340  and the compressive interface  116 . FIG. 3 shows the main printed circuit board first side  314 , the backer plate first side  336 , the power converter top surface  112 , and the compressive interface first side  364 . FIG. 4 is an exploded, bottom view of a power converter  110  formed in accordance with a preferred embodiment of the present invention. FIG. 4 shows the second side  312  of the main printed circuit board  310 , the second side  332  of the backer plate  330 , the second side  342  of the capacitor printed circuit board  340  and second side  360  of the compressive interface  116 .  
         [0028]    The main printed circuit board  310  includes a second side  312 , a first side  314  and holes  324  that allow for the passage of the cover screws  302 . The first side  314  includes semiconductors  316 , step down transformers  318 , capacitors  320  and interconnect receptacles  322  mounted thereto.  
         [0029]    [0029]FIGS. 5 and 6 illustrates the backer plate  330  in more detail. The backer plate  330  includes a first side  336  and a second side  332 . The second side  332  of the backer plate  330  includes cover mounting standoffs  334 . The first side  336  of the backer plate  330  includes the heat sink mounting standoffs  114 .  
         [0030]    The capacitor printed circuit board  340  includes a second side  342 , the power converter top surface  112  and holes  354  that allow for the passage of the cover screws  302 . The second side  342  of the capacitor printed circuit board  340  includes interconnects  344  and capacitor banks  346  extending therefrom. The power converter top surface  112  includes traces  352 . The compressive interface  116  includes a second side  360 , a first side  364  having power converter contacts  118 , and notches  366  that allow for the passage of the heat sink mounting standoffs  114 .  
         [0031]    The cover  122  supports the main printed circuit board  310 . The backer plate  330  is positioned between the main printed circuit board  310  and the capacitor printed circuit board  340 . The backer plate  330  ensures that the power converter  110  is held together securely.  
         [0032]    The cover mounting standoffs  334  of the backer plate  330  extend through the main printed circuit board  310  via the holes  324  to the cover  122 . The cover mounting standoffs  334  align with the cover holes  304 . The cover mounting standoffs  334  receive the cover screws  302  which engage the cover mounting standoffs  334  through the cover holes  304 . The cover screws  302  ensure that the backer plate  330  is secured to the cover  122 . Because the main printed circuit board  310  is positioned between the backer plate  330  and the cover  122 , the main printed circuit board  310  is secured within the cover  122  as the cover mounting standoffs  334  of the backer plate  330  are securely fastened to the cover  122  via the cover screws  302 .  
         [0033]    The heat sink mounting standoffs  114  of the backer plate  330  extend through the capacitor printed circuit board  340  via the holes  354 . The heat sink mounting standoffs  114  extend through the holes  354  up through the notches  366  of the compressive interface  116 . The notches  366  of the compressive interface  116  are positioned so that the compressive interface  116  abuts each of the heat sink mounting standoffs  114  and fits securely within the region bounded by the heat sink mounting standoffs  114 . Because the capacitor circuit board  340  is positioned between the backer plate  330  and the compressive interface  116 , the capacitor circuit board  340  mounts securely between the backer plate  330  and the compressive interface  116  as the compressive interface  116  is secured by the heat sink mounting standoffs  114  via the notches  366 .  
         [0034]    The capacitor printed circuit board  340  is electrically connected to the main printed circuit board  310  via the interconnect receptacles  322  which receive the interconnects  344  of the capacitor printed circuit board  340 . The interconnects  344  are in turn electrically connected to traces  352  located on the power converter top surface  112 . When the compressive interface  116  and the power converter top surface  112  are compressed together, the power converter contacts  118  of the compressive interface  116  contact the traces  352 , thereby forming an electrical path between the compressive interface  116  and the power converter  110 .  
         [0035]    In addition to holding the power converter  110  together securely, the backer plate  330  also provides support for the power converter  110 . The compression of the various components within the power converter  110  creates stresses and tensions within the power converter  110 . Additionally, the placement of the motherboard  130  on top of the power converter  110  and the heat sink  150  on top of the motherboard  130  causes even more stress and tension on the power converter  110 . The backer plate  330  provides physical support to the power converter  110  thereby preventing flexing and bowing of the power converter  110  under the stresses and tensions caused by the compression of the various components.  
         [0036]    The semiconductors  316 , step-down transformers  318 , capacitors  320  and interconnect receptacles  322  are fastened to the first side  314  of the main printed circuit board  310 , preferably, through solder connections. Additionally, the capacitor banks  346  and the interconnects  344  are preferably soldered to the second side  342  of the capacitor printed circuit board  340 . The capacitor banks  346  of the capacitor printed circuit  340  are located on the second side  342  of the capacitor printed circuit board  340  under the power converter top surface  112 . The capacitor banks  346  are electrically connected to the traces  152 , which are in turn electrically connected to the power converter contacts  118  when the compressive interface  116  and the power converter  110  are compressed together.  
         [0037]    When the motherboard  130  is positioned adjacent and compressed against the power converter  110 , the capacitor banks  346  are within close proximity of the IC  140 . Optionally, the capacitor banks  346  may be located at the edges of the capacitor printed circuit board  340 , not directly under the microprocessor of the IC  140 . Alternatively, the capacitor banks  346  may be positioned directly under the microprocessor of the IC  140 . That is, a middle section of the backer plate  330  may be cut out to provide space for the capacitor banks  346  to extend downward from the second side  360  of the capacitor printed circuit board  340 .  
         [0038]    In operation, the power converter  110  receives power from a power supply (not shown) at a first D.C. voltage. The power converter  110  receives the first D.C. voltage through the compressive interface  116 . The first D.C. voltage travels through the power converter contacts  118  of the compressive interface  116  and through the traces  352  located on the power converter top surface  112 . The interconnects  344  then receive the first D.C. voltage from the traces  352 . Then, the interconnect receptacle  322  located on the main printed circuit board first side  314  receives the first D.C. voltage. The step down transformers  318  then receive the first D.C. voltage via traces (not shown) on the main printed circuit board first side  314 . The step down transformers  318  then convert the first D.C. voltage to a second D.C. voltage. The semiconductors  316  control the logic and power input and output operations. The interconnect receptacle  322  then receives the second D.C. voltage via traces on the main printed circuit board first side  314 . The interconnects  344  then receive the second D.C. voltage from the interconnect receptacle  322  and transfer the second D.C. voltage to the traces  352 . The traces  352  then transfer the second D.C. voltage to the power converter contacts  118 .  
         [0039]    The power converter  110  is not fast enough to supply high current levels to the microprocessor of the IC  140  when the current is switched. Switching from low current to high current, for example 0 amps to 100 amps or higher, at very quick rates, such as 1 microsecond or faster, may preclude the power converter from providing a relatively constant voltage to the microprocessor of the IC  140 . The capacitors of the capacitor banks  346  are utilized to maintain a relatively constant voltage at the IC  140 . The capacitor banks  346  store energy received from the main printed circuit board  310 . Energy from the main printed circuit board  310  travels from the interconnect receptacles  322  to the interconnects  344 . The traces  352  then receive the energy from the interconnects  344  and then distribute the energy to the capacitors in the capacitor banks  346 .  
         [0040]    The capacitors of the capacitor banks  346  supply additional energy to the microprocessor of the ICU  140  during current switching. During the transient when the current is being switched from 0 to 100 amps, the energy stored in the capacitor banks  346  supply the extra energy need by the microprocessor of the IC  140 . Preferably, the power converter  110  supplies power to the capacitor banks  346  at voltages between {fraction (1/2)} volt to 2 volts. During the fast current transient, the capacitors in the capacitor banks  346  supply energy to the microprocessor of the IC  140  to maintain the voltage at the microprocessor until the power converter  110  can respond to recharge the capacitor banks  346  and provide a relatively constant voltage to the IC  140 .  
         [0041]    The capacitor banks  346  transfer energy to the power converter contacts  118  of the compressive interface  116  via the traces  352 . The pads and vias of the motherboard  130  connect the power contacts located on the IC socket  138 , which are in turn connected to the IC  140 . Alternatively, power supply contacts  142  of the IC  140  may receive the energy from the power converter contacts  118  compressed against the power supply contacts  142 . The transfer of energy from the capacitors of the capacitor bank  346  to the IC  140  maintains a relatively constant voltage supply at the IC  140  and the microprocessor within the IC  140 . During the fast current switch, the output voltage to the IC  140  changes less than 5%. Therefore, the capacitor banks  346  prevent excessive change of the input voltage from the power supply to the IC  140 .  
         [0042]    Inductance and resistance are minimized due, in part, to the location of the power converter  110  underneath the IC  140 . Because the power converter  110  and the microprocessor of the IC  140  are connected via short traces, the problems associated with inductance and resistance due to long traces are minimized. The close proximity of the power converter  110  and the capacitor banks  346  to the IC  140  allows high current switching with low inductance and resistance. The close proximity of the IC  140  and the microprocessor within the IC  140  to the power converter  110  and to the capacitors of the capacitor bank  346 , shortens the distance of the traces among the IC  140 , the power converter  110  and the capacitor bank  346 . Shorter traces yield lower inductance and resistance.  
         [0043]    Additionally, placing the capacitor banks  346  below the IC  140  provides better airflow to the IC  140 . Because the capacitor banks  346  are located underneath the IC  140 , the capacitor banks  346  do not block airflow to the microprocessor and other components of the IC  140 . Therefore, by placing the capacitors below the IC  140 , the area around the microprocessor is opened and more air flows around the IC  140  thereby cooling the IC  140 . Consequently, because the IC  140  is cooled efficiently by airflow, a smaller, lighter, and lower cost hear sink  150  may be utilized to cool the IC  140 .  
         [0044]    Alternatively the capacitor banks  346  may be placed in various other positions. For example, the capacitor banks  346  may be placed on the outer edges of the first side  136  or second side  132  of the motherboard  130 .  
         [0045]    Additionally, the side vents  128  of the power converter  110  provide airflow inside the power converter  110 . Because the air vents  128  are located on the sides of the power converter  110 , the power converter  110  is supplied with a different air stream than the air stream surrounding the IC  140 . That is, when power is supplied to the IC  140 , the IC  140  heats the surrounding air and may cause additional thermal problems. The placement of air vents  128  on the sides of the power converter  110  provides two different air streams for thermal management: one air stream to the power converter  110 ; and the other air stream to the IC  140 . Therefore, the power converter  110  is not cooled by an air stream heated by the IC  140 .  
         [0046]    While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is therefore contemplated by the appended claims to cover such modifications that incorporate those features coming within the scope of the invention.