Abstract:
A power management circuit for use in a peripheral module such as a network interface card is presented. The circuit facilitates low power network monitoring for ‘Wake On LAN’ or ‘Plug In and Go’ applications as well as for network-initiated configuration and operation of a peripheral or network interface card&#39;s host computer. The circuit detects initial application of operational power and initiates assertion of sufficient power for evaluating the earlier programmed configuration parameters. Upon completion of the evaluation of the configuration parameters, the circuit sustains standby power to the portion of the network interface card that is monitoring the network traffic for a wake-up command when the configuration parameters so dictate.

Description:
BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates to power management in computer peripheral devices, and more specifically, power management of peripheral devices employing various cognitive levels for purposes of power conservation. 
     2. The Relevant Technology 
     Computers from their original inception have undergone significant evolutionary changes both in operation and configuration. For example, computers originally were largely physically bulky in size and inefficient in power consumption, resulting in fixed site devices requiring constant interconnection with generally limitless power sources. As electronics were integrated, the physical dimensions of computers were reduced even to small portable form factors. For a computer to be truly portable, it became necessary for the computer to utilize an independent portable power source such as a battery. Those familiar with battery technologies as they relate to portable computers appreciate the tension between a desirable small form factor and an also desirable limitless power source. As these two ideals met reality, considerable frustration was born. 
     Significant re-engineering and refinement of computers relating to their appetite for operating power continues as does the ongoing refinement of portable power sources, namely batteries. Many approaches such as powering only essential components have also been undertaken yielding great success toward conserving available portable power. 
     Other advances in computers relate to a computer&#39;s extensibility or its ability to extend its performance or capabilities through the use of interconnections with other devices including other computers. Such interconnections are commonly known as “networks” having various topologies and standards known by those of skill in the art. Since the specifications and standards for these various network topologies evolves and computational capabilities advances, computer developers have created various standard interfaces through which replaceable network interface modules capable of directly interacting with the networks may be utilized. These network interface modules or cards have a standard interface for coupling to the computer and another interface customized to interact with the network standard. In order to facilitate the translation of data from the computer to the network, these network interface modules or cards are also comprised of electronic circuitry that possess their own appetite for operational power. 
     Those of skill in the art appreciate the various standards for these interface cards that include the PCMCIA, PCI and mini PCI interface card standards. These interface cards or peripherals traditionally physically and electrically interface with a computer via card slots located in the computer. Since these peripheral cards become appendages to the computer, they rely on the computer to provide operational power. Such a dependency further burdens the limited operational power resident or available to the computer. 
     In further attempts by computer designers to manage the available power, computer designs have resorted to supplying operational power to peripheral modules only when the modules are active and interacting with the network on behalf of the computer. While such an “all-or-nothing” approach proves advantageous to the conversation of portable power resources, the wholesale shutting-down of a network interface card virtually isolates the computer from other network resources and ignores all interaction of the network with the computer. In further attempts to address this dire situation, peripheral card designs have attempted to partition more essential and less-essential network interface circuitry on the peripheral card and apply power to only those portions of the circuitry that directly listen for network commands. However, such approaches have traditionally required the computer to be originally powered and then undergo significant configuration followed by the selective removal of power to the less essential portions of the interface card circuitry. 
     There is also great interest in the computer networking world to develop an approach that enables a computer user to have their computer operably configured to a network through a remote configuration means that only requires the user to physically connect their computer to the network and to main power. Such an approach would require the computer network interface to continually monitor the network traffic for relevant configuration information. 
     Therefore, it would be an advancement in the art to develop a power management circuit for use on a interface card or peripheral module that could autonomously determine a low power configuration as assigned and self configured to that setting thereby autonomously assuming a low or reduced power consumption state without significant computer interaction. 
     SUMMARY OF THE INVENTION 
     The present invention provides low-power approach to determining when the network monitoring portion of the network circuitry should remain powered and a low-power approach to asserting such power to the circuitry. There is interest in supporting emerging technology relating to simplification and remote control of computers on a network. The present invention provides a solution to supporting functionality such as what is becoming commonly known as “Wake-On-LAN (WOL)” or “Plug In and Go (PIG)” functionality. Such functionality requires power to the network card such as the mini PCI LAN/Modem card upon the assertion of AC power to the computer. In a preferred embodiment, the network card is comprised of a non-volatile memory device containing configuration parameters dictating whether the network card should implement these streamlined configuration functionality. In order to support such functionality, the network card needs to switch power to evaluation circuitry that can read and evaluate the configuration parameters, and when the configuration parameters specify the use of this functionality, then sustain the assertion of power to the network monitoring portion of the network interface circuitry. 
     The power management circuit of the present invention is comprised of two main sections, the power switch circuit and the power switch control circuit. The power switch, in the preferred embodiment, utilize P-channel MOSFETs that have a very low ‘ON’ resistance in order to minimize the voltage drop across the switch devices. Two series configured MOSFET switches are place on each input power path to prevent back powering through the intrinsic diodes in the MOSFET. The power switch control circuit controls the power switch circuit for asserting power to the network monitoring portion of the network circuitry under two conditions: (i) upon initial application of power to the computer when the configuration parameters need to be evaluated and (ii) when an evaluation of the network configuration parameters specify that monitoring functionality such as WOL or PIG are requested. 
     Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the manner in which the above-recited and other advantages and features of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawing depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 is a block diagram of a system comprised of a computer and peripheral module within which the power management circuit of the present invention may be practiced, in accordance with a preferred embodiment; 
     FIG. 2 is a detailed block diagram of the power management circuit, in accordance with a preferred embodiment; and 
     FIG. 3 is a detailed circuit diagram of the power management circuit, in accordance with a preferred embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the present invention may be described more fully hereinafter with reference to the accompanying drawings, in which the preferred embodiment of the present invention is described, it is contemplated by the inventors that those of skill in the art may modify the invention here described while still achieving the favorable results of this invention. Therefore, the description which follows describing a preferred embodiment should be appreciated for its broader teachings and not as limiting upon the invention. 
     Referring now to the accompanying drawings, the present invention while described largely for incorporation into a computer and even a personal computer environment, also has broad applications to integration within other digital devices which may assume other form factors different from a more traditional computer environment. Such broader digital device applications are contemplated by the inventor and are deemed to be within the scope of the present invention. 
     FIG. 1 depicts a computerized environment within which the power management circuit may be practiced. While computer  100  may be comprised of additional functional components not depicted such as memory, hard drives, video displays, etc., such additional components are not herein shown as they would only encumber the drawing and distract from the present invention. Therefore, only the power management components and other components that make possible the power management novelties of the present invention are herein depicted. 
     In FIG. 1, a computer  100  is generally depicted as interfacing with a peripheral module  102 . Those of skill in the art appreciate that a peripheral module may take various form factors including PCMCIA, PCI, mini PCI and other various support module form factors. Such peripheral modules provide extensibility to computer  100  by providing interface functionality between computer  100  and a network or other interconnection topology. 
     In order to facilitate operation, computer  100  receives electrical power in the form of main power or AC power  104  and alternatively portable or battery power  106 . Computer  100  is further comprised of a power management system  108  for partitioning the power resources into a distributed power architecture. In FIG. 1, power management block  108  partitions the available power into an auxiliary input power rail  110  and a main input power rail  112 . Auxiliary input power rail  110  provides power more traditionally used for standby and holdup functionality within a computing environment, while main input power rail  112  provides power utilized by computer  100  and peripheral module  102  during full operational functionality. Such power, both auxiliary input power rail  110  and main input power rail  112  are generally made available as generated without additional conditioning or modifications at an interface  118  with which peripheral module  102  interfaces. 
     Computer  100  is further comprised of the PCI bus controller interface  132 . The present invention in its preferred embodiment depicts a PCI interface standard, those of skill in the art appreciate that other standards may also be incorporated which implement a bus interface architecture other than the PCI or mini PCI interface. In the preferred embodiment, a mini PCI interface is depicted which facilitates the passing of both auxiliary input power rail  110  and main input power rail  112  to interface  118 . 
     FIG. 1 further depicts computer  100  as comprising a microprocessor  114  having a control and data interface  116 . Those of skill in the art appreciate that a computer  100  will certainly be comprised of a form of microprocessor or other logic execution device including micro-controllers, digital signal processors (DSP), and may even include logic generated sequencing such as state machines, etc. In the present invention, microcontroller  114  is depicted for its ability via control and data bus  116  to pass or write configuration data into peripheral module  102  dictating a configuration or power state as well as other capabilities to peripheral module  102 . While the preferred embodiment contemplates micro-processor  114  as being the originator of such configuration data, it is also contemplated within the present invention that such configuration data may have originated or been preconfigured within peripheral module  102  thereby minimizing the need for a control and data bus  116  interface with peripheral module  102  for facilitating or seeding peripheral module  102  with configuration information. 
     Peripheral module  102  in FIG. 1 is depicted as receiving auxiliary power  120  and main input power  122  from computer  100  via interface  118 . Both auxiliary input power  120  and main input power  122  are presented to a power management circuit  124 . The preferred embodiment of the present invention employs power management circuit  124  to provide power management to facilitate a power conversation structure within peripheral module  102 . Segregated portions of network interface circuitry, located within a network monitoring circuitry  130 , monitor network traffic for commands that may dictate or alternative request that peripheral module  102  notify computer  100  via a control or interrupt signal (not shown) of a request by the network for computer  100  to transition to a higher alert stage, such as a full operational state, thereby enabling the network and computer  100  to interact via a control and data path  126 . 
     Those skilled in the art of network technology appreciate the emergence of designs and technology which enable a computer to achieve a very low power state, even an apparent “off” state and to be awakened from that state by a peripheral module comprised of operational circuitry which is also in a largely “off” state and other monitoring portions which are diligently evaluating network traffic to determine the presence of a specifically addressed wakeup command for that specific computer and peripheral module. Such functionality commonly goes by various names or acronyms such as “wake-on-LAN” (WOL) or “plug-in-go” (PIG). The present invention in its preferred embodiments find application to these and other related power efficient approaches. 
     FIG. 2 depicts a more detailed block diagram of power management circuit  124 , and its preferred embodiment. Power management circuit  124  performs the primary function of generating a switched power  128  utilized by the wake-up or monitoring portions of the network monitoring circuitry  130  (FIG.  1 ). As discussed above, network monitoring circuitry  130  for architectures that employ a low power stand-by network monitoring feature, is partitioned into a stand-by or wake on command monitoring portion and a full operational portion. The full operational portion is powered by main input power  122  as depicted in FIG.  1 . The other stand-by or wake on demand portion of the circuitry is powered by switched power  128 . 
     In the preferred embodiment of the present invention, power management circuit  124  receives auxiliary input power  120  and main input power  122  and through a determination of specific configurations within the peripheral module, determines when to generate switched power  128  from auxiliary input power  120  and when to generate switched power  128  from main input power  122 . Therefore, power management circuit  124  is comprised of two circuit portions, (i) a power switch circuit  142  which selectively routes auxiliary input power  120  and main input power  122  to become switched power  128 , and (ii) a power switch control circuit  140  which makes such a determination and asserts the appropriate control signals to power switch circuit  142 . 
     It should be kept in mind that when peripheral module  102  is in full operational mode, main input power  122  will supply switched power  128 . Therefore, an important function of power switch control circuit  140  is to determine the circumstances under which power switch control circuit  140  should assert switch power  128  when auxiliary input power  120  is presented thereto. That is to say, power switch control circuit  140  evaluates the peripheral module configuration to determine when the peripheral module has been preconfigured or programmed to participate in network monitoring functionality such as waking or arousing the computer upon the receipt of a network command instructing the peripheral module to do so or when a computer and peripheral module have recently been interfaced with a network and power either in the form of AC power  104  (FIG. 1) or battery power  106  (FIG. 1) has been made available to computer  100 . Under at least these two circumstances, power switch control circuit  140  must determine whether to activate this network monitoring portion of network monitoring circuitry  130  (FIG. 1) or remain dormant and inactive until otherwise directed by computer  100 . 
     Power switch control circuit  140  is comprised of (i) a supervisor circuit  144  for asserting a one time configuration evaluation pulse upon the initial connection of computer  100  and peripheral module  102  to power, and (ii) circuitry for determining when an enabling signal should be sustained in order to maintain the continued assertion of switched power  128  to keep the stand-by or network monitoring portions of the network monitoring circuitry active and listening for specific commands from the network. 
     Supervisor circuit  144  receives auxiliary input power  120  and, upon a rising edge of the receipt of auxiliary input power  120 , generates a pulse in the form of output  146  which drives into an “OR” gate  148 , which when directed by supervisor circuit  144  asserts an output  160  causing switched power  128  to momentarily apply power to evaluation logic capable of determining the preconfigured state of peripheral module  124 . 
     Power switch control circuit  140  is further comprised of a non-volatile memory  150  and evaluation logic  156 . As mentioned earlier, the configuration of peripheral module  102  is either dictated or configured by computer  100  or preconfigured, such as at the factory, by another source, in either approach, non-volatile memory  150  may be comprised of various configuration parameters. FIG. 2 depicts a configuration parameter  152  designating a low power state, figuratively depicted as a low power state D 3 , in accordance with one well known power management configuration architecture. Under such a power designation, configuration parameter  152  when asserted, designates to peripheral module  102  that it should assume a low operational network circuitry deasserted. Additionally, a configuration parameter  154  depicts a power management event parameter dictating that the peripheral module should assert or apply power to the portion of the network monitoring circuitry that continuously monitors the network for wake up types of commands. 
     Evaluation logic  156  combines the inputs of configuration parameters  152  and  154  to determine an output  158  which, under the correct input conditions, causes the sustained assertion of switched power  128 . It should be pointed out that both evaluation logic  156  and non-volatile memory  150  are further configured to receive operational power from switched power  128 . Such power is initially asserted as a result of supervisor circuit  144  upon the initial connection of computer  100  with operational or available input power. While under the effect of switched power  128  as initiated by supervisor circuit  144 , evaluation logic  156  upon determining that the wake-up or power management features of the peripheral module have been specified to be invoked, asserts output signal  158  causing switched power  128  to be sustained prior to the expiration of the pulse as asserted by supervisor circuit  144 . As a result, the wake-up on command portion of the network monitoring circuitry remains activated via switched power  128 . 
     FIG. 3 depicts a detailed circuit diagram of power management circuit  124 . Specific voltages and components have been designated in FIG. 3 in accordance with a preferred low voltage implementation of the present invention. Power switch circuit  142  is comprised of a series configured pair of semi-conductor switches,  182  and  184 , for relaying auxiliary input power  120  to switched power  128 . Likewise, switches  188  and  190  facilitate the passing or relaying of main input power  122  to switched power  128 . While the present embodiment depicts a series configured plurality of controllable switches, it is contemplated that single switches in the form of relays or otherwise may also be implemented. The present configuration of a plurality of switches results from inherent forward biasing conduction of diodes within the specific selected components. While various switching devices may be employed, one suitable device for implementing the configuration of power switched circuit  142  is a MOSFET, and more particularly P-channel MOSFET such as a S12315DS device which is readily available. 
     The power switch control circuit  140  (in FIG. 2) is comprised of the remaining elements as depicted in FIG.  3 . Supervisor circuit  144  is comprised of a pulse generating circuit or device such as a MAX810 or other suitable device capable of generating a pulse of sufficient duration to enable the configuration parameters to be read and evaluated to make a determination as to whether to sustain assertion of switch power  128  to a stand-by or network monitoring portions of the network monitoring circuitry. The combination of the initial pulse as generated by supervisor circuit  144  is combined with any resulting pulse from an evaluation of the configuration parameters through the use of a logic gate  148  (in FIG. 2) taking the form of an OR gate and generating an output  160 . Output  160  directly drives the gates of portions of power switch  142  and indirectly drives the gates of other portions of power switch  142  via biased transistor  192 . Biased transistor  192  may be created from discrete components using biasing techniques known by those of skill in the art, or alternatively may be implemented using a pre-biased transistor such as a MUN5214T1 readily available. A biased transistor  194  may be likewise comprised of discrete components or may be implemented using a self-contained bias device such as a MUN5114T1 or like device. 
     Evaluation logic such as logic  156  may be comprised of discreet components or other forms of available logic circuitry which may be resident on portions of the LAN modem circuitry logic including any available application-specific integrated circuits (ASIC). Those of skill in the art appreciate the various components that may be employed to implement non-volatile memory  150 . The miscellaneous other circuit components such as resistor  186  and  196  provide pull-up capability or other series resistance functionality known by those of skill in the art. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.