Abstract:
A device package that receives a voltage from a power supply on a motherboard and that includes provisions for a voltage control element that controls the power supply voltage. The provisions for the voltage control element are such that the voltage from the power supply has a first voltage if the voltage control element is installed and a second voltage if the voltage control element is missing. Such a device is useful in (computer) systems having wiring boards with power supplies that produce output voltages that depend on adjust voltages on adjust inputs. The provisions of the device package can then set the adjust voltage such that the power supply has a first voltage if the voltage control element is installed and a second voltage if the voltage control element is missing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional application of U.S. patent application Ser. No. 10/442,529, filed May 20, 2003 now U.S. Pat. No. 7,166,934, which is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to system integration. More particularly, this invention relates to using a device package to control the voltage from a power supply. 
   2. Description of the Related Art 
   Digital computers are used to perform a wide variety of tasks in business, industry, government, education, entertainment, and the home. Modern computers often incorporate powerful integrated circuits to implement complex functions such as 3-D graphics, voice recognition, and the like. 
   Because of the wide range of computer uses and applications, together with the cost constraints imposed by different users, computer manufacturers have had to produce computers with different capabilities to satisfy different market segments. This has often required different configurations of computer microprocessors, dedicated digital processors, memory, motherboards, input/output functions, display devices and power supplies. For example, while desktop computers can benefit by using higher power consumption to improve performance, in portable computers low power consumption may be more important than high performance. One method of reducing power consumption is to reduce the power supply voltage. In particular, the power consumption of random access memory (RAM) can be significantly reduced by using a lower power supply voltage. 
   Because of competitive pressure, even as computer systems become more powerful their manufacturers are pressured to control costs. One method of controlling costs is to reduce the number of different types of devices that must be purchased and inventoried. For example, a significant cost when manufacturing a computer system is the motherboard, which usually carries the system&#39;s power supply and RAM. Since some RAM will not operate properly on a reduced voltage, and since processors require specific operating voltages, a manufacturer has had to configure the power supply voltage to match the RAM and the processor, possibly requiring multiple voltage supplies. Having to configure the power supplies to match the RAM and the processor causes logistical problems for computer manufacturers. 
   While RAM typically has been located on a motherboard, a new semiconductor package, the mobile application package (MAP) from NVIDIA, the assignee of the present invention, packages both RAM and a Graphics Processor Unit (GPU) together. Because of the different cost, speed, and performance options available with RAMs and GPUs, such packaging enables different processor-RAM combinations to be offered to higher-level system manufacturers. This enables those manufacturers to offer systems with different cost, speed, and performance options while using the same motherboard, but without the logistical problems of configuring that motherboard for different RAM types. Additionally, MAP-packaged processor-RAM combinations benefit the MAP manufacturer by allowing for competitive pricing and backup suppliers. 
   While packaging processors and RAM together is highly beneficial, manufacturers nonetheless still had to match their power supplies to the processor and RAM. Tracking the various configurations remained difficult. For example, a low power MAP-packaged processor-RAM combination might be able to operate on low voltage (say 2.7V); while another MAP-packaged processor-RAM combination might be operable at both 3.3 and 5 volts. Furthermore, to optimize performance, another MAP-packaged processor-RAM combination might operate with the RAM at 3.3V while the GPU might operate best at 5V. Complicating the problem is that the MAP-packaged processor-RAM combination supplier might want to be free to use various GPU-RAM combinations based on cost or supply considerations without notifying the computer manufacturer what power supplies are required. 
   Therefore, a method of controlling a power supply or power supplies using a device package having both memory and a processor would be beneficial. 
   SUMMARY OF THE INVENTION 
   The principles of the present invention provide for device package-based control of off-device package power supplies. Beneficially, the device-package manufacturer implements such control based on the requirements of the packaged devices. Such device package-based control is suitable for automatically controlling one or more power supplies using a standardized printed circuit board interface. Preferably, the device package-based control is implemented such that the power supply voltage(s) applied to a processor, such as a GPU, and to memory, such as RAM, are optimized for the particular GPU, RAM, and/or application. 
   A device package that is in accord with the principles of the present invention includes an input for receiving a voltage from a power supply. Furthermore, that device package includes provisions for a voltage control element for controlling the power supply voltage. The provisions for the voltage control element are such that the power supply voltage has a first voltage if the voltage control element is installed and a second voltage if the voltage control element is missing. 
   A computer system that is in accord with the principles of the present invention includes a wiring board having a power supply that produces an output voltage that depends on an adjust voltage on an adjust input. A device package, which receives the output voltage, has provisions for a voltage control element for setting the adjust voltage. The provisions for the voltage control element are such that the power supply voltage has a first voltage if the voltage control element is installed and a second voltage if the voltage control element is missing. 
   A method of assembling a system that is in accord with the principles of the present invention includes coupling both a memory device and a voltage control resistor to a MAP substrate. The voltage control resistor (which may be a zero-ohm resistor) signals the required operating voltage of the memory device. The MAP substrate is coupled to a circuit board such that the power supply has an output that depends on the voltage control resistor. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
       FIGS. 1A and 1B  show computer systems that are in accord with embodiments of the present invention. 
       FIG. 2  shows a computer system that is in accord with another embodiment of the present invention. 
       FIG. 3  shows a computer system that is in accord with yet another embodiment of the present invention. 
       FIG. 4  illustrates using conductive balls as switch (resistor) elements. 
       FIG. 5  shows a computing system that is in accord with the principles of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with those embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of embodiments of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the embodiments of the present invention. 
   The principles of the present invention provide for device packages having a standardized interface and provisions for controlling the output voltage of a power supply that is located on a mother board, such as a printed circuit board. Various embodiments of the present invention provide for switch control of a power supply, resistive control of a power supply, and both resistive and switched control of a power supply. 
     FIGS. 1A and 1B  each illustrate a system  100  having power supplies that are controlled by provisions of a device package. The system  100  includes a first power supply regulator  102 , a second power supply regulator  104 , and a MAP (Mobile AGP Package)  106 , all of which are located on a motherboard  110 . The voltage outputs of the voltage regulators  102  and  104  are respectively adjusted by varying the voltages on adjust lines  114  and  116 . The adjust voltage on line  114  is determined by a first voltage divider that divides the output voltage of regulator  102 , which is available on line  120 . The first voltage divider includes a resistor  115  that extends between lines  120  and  114 , and a second resistor  117  that extends from the adjust line  114  to ground. The voltage on adjust line  116  is determined by a second voltage divider that divides the output voltage of regulator  104 , which is available on line  122 . The second voltage divider includes a resistor  119  that extends between lines  122  and  116 , and a second resistor  121  that extends from adjust line  116  to ground. The first and second voltage dividers include additional elements that are subsequently described. 
   Referring to  FIG. 1A , the voltage on adjust line  114  sets the voltage from the regulator  102 . By increasing the voltage on adjust line  114  the voltage on line  120  can be decreased. To that end, the first voltage divider includes a resistor  123  that can be selectively switched between lines  114  and  120  by a transistor  124 . The gate  125  of transistor  124  is pulled high by a resistor  126 . As long as the gate remains high, the transistor  124  is ON, and the resistor  123  is switched into operation to decrease the output voltage by reducing the voltage drop between lines  120  and  114 . Resistor  130 , resistor  132 , and transistor  134  impact the second voltage divider in the same manner as resistors  123  and  126 , and transistor  124  impact on the first voltage divider. 
   Still referring to  FIG. 1A , the output voltage of regulator  102  is applied to RAM  150  within the MAP  106 , while the output voltage of regulator  104  is applied to a GPU  152  within the MAP  106 . Furthermore, the gate of transistor  124  is connected to a switch  154  within the MAP  106 , while the gate of transistor  134  is connected to a switch  156  within the MAP  106 . The switches  154  and  156  are features that provide for setting the output voltages of the regulators, as is described below. 
   As shown in  FIG. 1A , switch  154  is closed, thus connecting the gate  125  of transistor  124  to ground. This causes the transistor  124  to turn OFF, thus disconnecting the resistor  123  from line  114 . This reduces the voltage on line  114 , which, in turn, increases the voltage on line  120  to the RAM  150 . However, the switch  156  is open, thus enabling the gate  135  of transistor  134  to remain HIGH. This causes transistor  134  to turn ON, connecting resistor  130  to adjust line  116 . This increases the voltage on line  116 , which, in turn, decreases the voltage on line  122  to the GPU  152 . Therefore, the states of the switches  154  and  156  control the voltages to the RAM and GPU, respectively. 
   Referring to  FIG. 1B , the voltage on adjust line  114  sets the voltage from the regulator  102 . The input of an inverter  160  is pulled high by resistor  127 . The output of inverter  160  and gate  125  of transistor  124  is pulled low, causing transistor  124  to turn OFF, thus disconnecting the resistor  130  from line  116 . This reduces the voltage on line  116 , increasing the voltage drop between lines  122  and  116 . Resistor  130 , resistor  133 , inverter  162 , and transistor  134  impact the second voltage divider in the same manner as resistors  123  and  127 , inverter  160 , and transistor  124  impact on the first voltage divider. 
   Still referring to  FIG. 1B , the output voltage of regulator  102  is applied to RAM  150  within the MAP  106 , while the output voltage of regulator  104  is applied to a GPU  152  within the MAP  106 . Furthermore, the input of inverter  160  is connected to a switch  154  within the MAP  106 , while the input of inverter  162  is connected to a switch  156  within the MAP  106 . The switches  154  and  156  are features that provide for setting the output voltages of the regulators, as is described below. 
   As shown in  FIG. 1B , switch  156  is open, thus enabling resister  133  to pull the input of inverter  162  high. The output of inverter  162  is pulled low, causing the transistor  134  to turn OFF, thus disconnecting the resistor  130  from line  116 . This reduces the voltage on line  116 , which, in turn, increases the voltage on line  122  to the GPU  152 . However, the switch  154  is closed, thus enabling resister  127  to pull the input of inverter  160  low, enabling the gate  125  of transistor  124  to remain HIGH. This causes transistor  124  to turn ON, connecting resistor  123  to adjust line  114 . This increases the voltage on line  114 , which, in turn, decreases the voltage on line  120  to the RAM  150 . Therefore, the states of the switches  154  and  156  control the voltages to the RAM and GPU, respectively. 
   By incorporating the principles of the present invention, a system manufacturer can allow the MAP supplier to control the voltage applied to the RAM  150  and to the GPU  152 . Therefore, the MAP supplier is free to control whether or not a device within the MAP should operate at a reduced or at an elevated voltage. Furthermore, the power supply voltage control is “selected” by the inclusion or exclusion of a resistive element, such as a zero ohm resistor, a solder ball, a fuse-able interconnect, or a jumper wire. The fuse-able interconnect can be opened, e.g., blown, by using a laser or inducing a large current through the interconnect, optionally prior to populating a MAP with a GPU or memory devices. While  FIG. 1A  shows the switches  154  and  156  as being referred to ground, this is not required. The switches could also be switched to the output of a power supply, provided, of course, that the resistors  126  and  132 , and the transistors  124  and  134 , are configured to work with the output of the power supply. 
   Furthermore, in some embodiments power supply regulator  102  and power supply regulator  104  may be replaced with a voltage regulator module configured to receive a multi-bit voltage identification, and produce several output voltages. A multi-bit voltage identification may be produced by lines  114  and  116 . 
   While  FIGS. 1A and 1B  illustrate power supply control by selectively switching resistors  123  and  130  into parallel with resistors  115  and  119 , respectively, in some applications this may not be optimal. To reduce part count and burdens on the computer system manufacturer, it some applications it may be better to place voltage control resistors inside the MAP itself. For example  FIG. 2  illustrates two different techniques of controlling power supplies by placing “voltage adjust” resistors within the MAP device. 
   Refer now to  FIG. 2  for a depiction of a system  200  that controls a first power supply regulator  202  and a second power supply regulator  204  using resistors  206  and  208  inside a MAP  210 , all of which are located on a motherboard  212 . The voltage regulators  202  and  204  are respectively controlled by varying the voltages on adjust lines  214  and  216 . The voltage on adjust line  214  is determined by a first voltage divider that divides the output voltage of regulator  202  on line  220 . The first voltage divider is comprised of the resistor  206  that extends between lines  220  and  214 , and a second resistor  215  that extends from line  214  to ground. The voltage on adjust line  216  is determined by a second voltage divider that divides the output voltage of regulator  204  on line  222 . The second voltage divider includes a resistor  219  that extends between lines  222  and  216 , the resistor  208 , which is parallel with resistor  219 , and a resistor  221  that extends from adjust line  216  to ground. 
   Still referring to  FIG. 2 , the voltage on adjust line  214  depends on the resistance values of resistors  206  and  215 . Assuming the manufacturer of the MAP specifies the value of resistor  215 , that manufacturer can then control the voltage on line  220  by installing a resistor  206  having the correct value. Similarly, assuming the manufacturer of the MAP specifies the value of resistors  219  and  221 , that manufacturer can control the voltage on adjust line  216  by installing a resistor  208  having the correct value. Furthermore, by leaving the resistor  208  out of the package, a default voltage from the voltage regulator  204  can be selected. 
   While placing the voltage adjust resistors within the MAP is beneficial in reducing overall part count, in fact there is little room within available MAPs for the resistors. Furthermore, placing the resistors in the MAP can result in increased electrical noise.  FIG. 3  illustrates techniques of addressing some of the problems by combining features from  FIGS. 1 and 2 . 
   Refer now to  FIG. 3  for a depiction of a system  300  that controls a first power supply regulator  302  and a second power supply regulator  304  using features of a MAP  310 , all of which are located on a motherboard  312 . The voltage regulators  302  and  304  are respectively adjusted by varying the voltages on adjust lines  314  and  328 . The voltage on adjust line  314  is determined by a first voltage divider that divides the output voltage of regulator  302  on line  320 . The first voltage divider is comprised of a resistor  316  that extends between lines  320  and  314 , a second resistor  317  that extends from adjust line  314  to ground, and by a resistor  320  that is selectively switched to be in parallel with resistor  317 . Selective switching is performed by a switch  322  within the MAP  310 . If the manufacturer of the MAP  310  installs a zero-ohm resistor across switch  322  the voltage on line  314  will drop, thus adjusting the voltage on line  320 . However, if switch  322  is open, the output of the regulator  302  depends only on resistors  316  and  317 . 
   Still referring to  FIG. 3 , the voltage on adjust line  328  is determined by a second voltage divider that divides the output voltage of regulator  304  on line  330 . The second voltage divider includes a resistor  319  that extends between lines  330  and  328 , a resistor  334  that extends from adjust line  328  to ground, and a series connection of a resistor  336  of a resistor  338  that run parallel to resistor  319 . 
   Still referring to  FIG. 3 , the junction  344  of resistors  336  and  338  is electrically available inside the MAP  310 . It should be noted that while resistor  336  is illustrated as being inside the MAP  310 , this is not required. Placing resistor  336  within the MAP  310  enables the manufacturer of the MAP  310  to control the voltage on line  330 , but at the expense of increased noise and manufacturing difficulty. In any event, the junction  344  is electrically connected to a switch  346 . By selectively closing the switch  346  the voltage at adjust line  328  can be changed. The selective switching is beneficially performed by having the manufacturer of the MAP  310  selectively install a zero-ohm resistor across switch  346 . If the switch  346  is closed, the voltage on line  328  will drop since resistors  334  and  338  are not in parallel. But, if the switch is open, the voltage will rise since the series combination of resistors  336  and  338  are now parallel with resistor  319 . 
   It should be noted that MAPs have compact and inexpensive attachment footprints that can use ball grid arrays to make contacts with contact pads on the motherboard. Ball grid arrays are more flexible than prior art slot connections or socket connections since they enable customizable attachment footprints. By selectively installing or leaving out particular zero-resistance balls in the ball grid, switches can be selectively opened or closed. For example,  FIG. 4  illustrates conductive ball  400  that runs between a ground line  402  and an electrical contact  404 , say of switch  346  in  FIG. 3 . The ground line  402  might be a pad on a motherboard, say the motherboard  312  of  FIG. 3 . Additionally, if desired, nonconductive balls can be added to the ball grid to ensure mechanical and electrical performance. This flexibility enables easily customizable features that can support different versions of the industry standard AGP (accelerated graphics port) interface. 
     FIG. 5  is an illustration of a computing system generally designated  550  and including a host processor  554 , a host memory  552 , a system interface  555 , a MAP  506 , and resistors  516 ,  517 ,  519 , and  521 . Computing system  550  may be a desktop computer, server, laptop computer, palm-sized computer, tablet computer, game console, cellular telephone, computer based simulator, or the like. In one embodiment of computing system  550  host memory  552 , host processor  554 , system interface  555 , MAP  506 , and resistors  516 ,  517 ,  519 , and  521  are coupled to a printed wiring board. 
   Host processor  554  may include a system memory controller to interface directly to host memory  552  or may communicate with host memory  552  through a system interface  555 . System interface  555  may be an I/O (input/output) interface or a bridge device including the system memory controller to interface directly to host memory  552 . Examples of system interface  555  known in the art include Intel® Northbridge and Intel® Southbridge. Host processor  554  communicates with MAP  506  via system interface  555 . 
   Computing system  550  controls a first power supply regulator  502  and a second power supply regulator  504  using resistors and optional resistors inside MAP  506 , such as shown in MAP  210 , MAP  106 , and MAP  310 . The voltage regulators  502  and  504  are respectively controlled by varying the voltages on adjust lines  514  and  516 . The voltage on adjust line  514  is determined by a first voltage divider that divides the output voltage of regulator  502  on line  520  and one or more resistors within MAP  506  as shown in MAP  106  in  FIG. 1 , MAP  210  in  FIG. 2 , or MAP  310  in  FIG. 3 . The first voltage divider is comprised of the resistor  516  that extends between lines  520  and  514 , and a second resistor  517  that extends from line  514  to ground. The voltage on adjust line  516  is determined by a second voltage divider that divides the output voltage of regulator  504  on line  522  and one or more resistors within MAP  506  as shown in MAP  106  in  FIG. 1 , MAP  210  in  FIG. 2 , or MAP  310  in  FIG. 3 . The second voltage divider is comprised of the resistor  519  that extends between lines  522  and  516 , and a second resistor  521  that extends from line  516  to ground. 
   The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.