Patent Publication Number: US-11036270-B2

Title: Method and apparatus for providing standby power to an integrated circuit

Description:
RELATED APPLICATIONS 
     This application claims priority benefit of U.S. Provisional Patent Application Ser. No. 62/000,894, filed May 20, 2014 and entitled “Method and Apparatus for Providing Standby Power to an Integrated Circuit”, which is herein incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The disclosed method and apparatus relate to providing low power modes in an integrated circuit more particularly to providing integrated standby power within an integrated circuit. 
     BACKGROUND 
     Integrated circuits are ubiquitous today. They are used for a very diverse set of consumer electronics, military electronics and commercial electronics. One concern that is becoming common to all devices that employ integrated circuits is the need to reduce the amount of power consumed. One way to reduce power consumption in a device is to turn off portions of the device that are not required at particular times (i.e., limit functionality, or remove power). In many cases, it is desirable to maintain power to other portions of the device in order to allow a user to quickly access the functions of the device. 
       FIG. 1  is a simplified block diagram of system  100 . The system  100  can operate in either a “power on” mode or a “standby” mode. A peripheral input/output (I/O) power supply  101  supplies power to one or more I/O devices  103 . This power is always provided. The I/O devices  103  may include such things as an infra-red detector for receiving inputs from a infra-red emitting remote control device, such as a television or set top box remote control. Other such I/O devices include: (1) receivers for Multimedia over Coax Alliance (MoCA) commands received over an interface that operates in accordance with the well-known MoCA standard for communications over coaxial cable; (2) front panel controls; (3) Ethernet receivers; (4) radio frequency (RF) receivers; or (5) local area network (LAN) receivers. By ensuring that power is always supplied to the I/O devices, such I/O devices remain functional and thus allow commands to be received to move the system  100  from standby mode to power on mode. 
     A relatively larger external main power supply  102  is connected to a standby island  104  within an integrated circuit  106 . The external power supply is also connected to a switch  108  that allows power to be connected to a core  110  of the integrated circuit  106  when in the system  100  is in power on mode or, alternatively, to the standby island  104  within the integrated circuit  106  during standby mode. The core  110  essentially includes all of the circuitry of the integrated circuit  106  that is not within the standby island  104 . The core power requirement is much greater than that of the standby island  104 . In some instances, the core  110  may draw as much as 4 Amps. However, the core  110  can be powered down during standby mode. Therefore, the switch  108  has to be capable of handling relatively high current with a minimal voltage drop. This requires the switch  108  to have a very low “on-resistance”. Such switches are difficult to integrate into the integrated circuit  106 . The result is that the system cost is increased due to the expense of the external switch (typically a large field effect transistor). 
     Accordingly, there is presently a need for a low cost means for switching from power mode to standby mode. 
     SUMMARY 
     Various embodiments of methods and structures are disclosed for reducing the cost of a system that has both power on mode and standby mode. Some of these embodiments are directed toward systems and methods for using an internal regulator that taps power from an external peripheral I/O power supply. The regulated power is supplied to a standby island that is isolated from an integrated circuit (IC) core module, allowing power to flow to the standby island when power is concurrently not being applied to the IC core module. A control output from the standby island allows a power supply control module within the standby power supply to turn an external main power supply on and off to remove power from the IC core module. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosed method and apparatus, in accordance with one or more various embodiments, is described with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict examples of some embodiments of the disclosed method and apparatus. These drawings are provided to facilitate the reader&#39;s understanding of the disclosed method and apparatus. They should not be considered to limit the breadth, scope, or applicability of the claimed invention. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale. 
         FIG. 1  is a simplified block diagram of a prior art system having both standby mode and power on mode. 
         FIG. 2  is a simplified block diagram of a system in accordance with one embodiment of the disclosed method and apparatus for reducing the cost of switching between power on mode and standby mode. 
         FIG. 3  is a simplified block diagram of a standby island in accordance with one embodiment of the disclosed method and apparatus. 
         FIG. 4  is a simplified block diagram of an alternative system in which the source of power to a standby island is switched. 
     
    
    
     The figures are not intended to be exhaustive or to limit the claimed invention to the precise form disclosed. It should be understood that the disclosed method and apparatus can be practiced with modification and alteration, and that the invention should be limited only by the claims and the equivalents thereof. 
     DETAILED DESCRIPTION 
       FIG. 2  is a simplified block diagram of a system  200  in accordance with one embodiment of the disclosed method and apparatus. The system  200  includes a peripheral input/output (I/O) power supply  201 , a relatively large external main power supply  202  and an integrated circuit  206 . The integrated circuit  206  includes one or more I/O devices  203 ; a standby island  204 ; an internal regulator  205 ; IC core module  210  within the integrated circuit  206 ; a peripheral I/O power supply output connection point  212 ; a main power supply output connection point  214 ; and a main power supply control connection point  216 . In accordance with one embodiment of the disclosed method and apparatus, the connection points  212 ,  214 ,  216  are pins of a ball grid array. Alternatively, the connection points  212 ,  214 ,  216  are pins of a pin grid array. However, it will be understood by those skilled in the art that there are many ways in which a connection can be made between conductors within the integrated circuit  206  and devices, components, circuits and the like external to the integrated circuit  206 . Any such way can be used. 
     The standby island is defined as that circuitry associated with (i.e., powered by) a standby island power rail. The IC core module is defined as that circuitry associated with (i.e., powered by) an IC core module power rail. The standby island power rail is isolated from the IC core module power rail. For the purposes of this disclosure, a power rail is defined as that set of conductors that are used to distribute power to circuits within an integrated circuit. 
     The internal regulator  205  provides regulated power to a standby island  204  within the integrated circuit  206  through the peripheral I/O power supply output connection point  212 . The standby island  204  includes all of the circuitry to which power should remain applied during standby mode. The power provided to the standby island  204  is isolated from the power that is provided to the IC core module  210  of the integrated circuit  206  by the larger power supply  202 . Due to the isolation of the standby island  204  from the IC core module  210 , power can be independently applied to and removed from the IC core module  210  and the standby island  204 . Accordingly, during standby mode, power is applied to the standby island  204  and removed from the IC core module  210 . 
     The peripheral I/O power supply  201  continues to supply power during standby mode, since the I/O devices need to be functional during standby mode in order to receive commands that might be provided by a user to remove the system  200  from standby mode. The internal regulator  205  is powered by the power supplied through the peripheral I/O power supply output connection point  212 . The internal regulator  205  provides a steady, clean power source to the standby island  204  with varying load conditions. 
     The standby island outputs a power control signal that is coupled through the main power supply control connection point  216  to a control input on the main power supply  202 . The main power supply  202  provides power to the IC core module  210  through the main power supply output connection point  214 . The I/O devices  203  output signals  218  to the standby island to allow a user to command the standby island to exit standby mode. In one embodiment, the I/O devices  203  reside outside the integrated circuit  206 . However, I/O drivers are provided on the integrated circuit  206 . In yet another alternative embodiment, the I/O devices and their drivers are outside the integrated circuit  206 . 
       FIG. 3  is a simplified block diagram of the standby island  204 . The standby island  204  includes a power control processor  302  and I/O circuitry  304 . The I/O circuitry  304  provides a means for external inputs  218  to command the system  200 . Such commands may originate at front panel switches and buttons (not shown) that allow a user to turn power on and off, and otherwise execute functions of the system  200 . Alternatively, the commands may come from external sources, such as Ethernet, LAN, infra-red sources, MoCA networks, etc. The I/O circuitry  304  will receive these inputs  218  and, in some cases, provide a signal  308  to the power control processor  302  to exit standby mode. In other cases, the commands may be received during power on mode. In this case, the I/O circuitry  304  may output signals  310  directly to the IC core module  210  to cause a function to be executed by the IC core module  210 . For example, in the case in which the system  200  is a set top box, commands such as channel selection, fast forward, etc. may be communicated directly from the I/O circuitry  304  to the IC core module  210 . 
     The power control processor  302  provides control signals  312  to various circuits within the IC core module  210 . Some of these controls signals  312  allow the power control processor  302  to slow clocks within the IC core module  210  in order to reduce power consumption. Other signals  312  allow the power control processor  302  to completely disable functions performed within the IC core module  210  to reduce power consumption. 
     The power control processor  302  also outputs a signal  314  to the main power supply  202  that will cause the main power supply  202  to shut down. In one embodiment, the signal  314  is coupled to a power control input port on the main power supply  202  that allows external control of the main power supply  202 . Alternatively, the signal  314  is coupled to a feedback control loop input on the main power supply  202 . The feedback control loop input allows an external source to raise or lower the output of the main power supply  202 . Typically, the feedback control loop input is coupled to the output of the power supply to regulate the voltage output from the main power supply  202 . However, in accordance with one embodiment of the presently disclosed method and apparatus, by applying a signal  314  to the main power supply feedback control loop port that is above the desired output voltage, the power control processor  302  can drive the main power supply output voltage to zero. 
     In accordance with one embodiment, the internal regulator  205  must provide sufficient regulation to ensure that the voltage applied to the standby island  204  during power on mode closely tracks the voltage applied to the IC core module  210  from the main power supply  202 . This is desirable, since the signals communicated from the standby island  204  to the IC core module  210  will require a common reference. In accordance with one embodiment, the regulator  205  uses the main power supply voltage as a reference to allow the regulator  205  to track the main power supply voltage. In one embodiment, the regulator  205  is a switched-capacitor regulator. It should be noted that since the regulator  205  is a relatively low power source, the efficiency of the overall system  200  may be greater than in systems which do not use an internal regulator powered from a discrete low power source, such as the peripheral I/O power supply  201 . 
     As noted above, the system  200  can operate in either power on mode in which power is applied to the IC core module  210  by the main power supply  202  or in standby mode. In standby mode, the standby island  204  commands the main power supply  202  to shut down. Power remains applied to the standby island and I/O devices through the peripheral I/O power supply  201  and the internal regulator  205 . It should be noted that the standby island  204  will stop using the main power supply output as a reference to the regulator  205  when in standby mode. 
       FIG. 4  is a simplified block diagram of an alternative system  400  in which the source of power to a standby island  404  is switched. An internal switch  402  is used to switch the source of power used by the standby island  404  in power on mode from the main power supply  406 , to a regulator  408  powered by a peripheral I/O power supply  410 , which is used in standby mode. Accordingly, during power on mode, the same power rail is used by both standby island  404  and IC core module  412 . Since the same power rail is used, there is no need to track and match the power source applied to the standby island  404  to the power supply used by the IC core module  412 . However, in order to ensure that power is continuously supplied to the standby island  404  during switch over from one power source to the other, a capacitor may be added at the standby island power input  414  to hold the voltage during the transition. The operation of the system  400  is essentially the same as that described with respect to the system  200  of  FIG. 2 , but for the use of the main power supply  406  during power on mode. 
     When the standby island  404  determines that it is appropriate to enter standby mode, a command signal is provided over a control line  416  from the standby island  404  to the main power supply  406 . The command signal causes the main power supply to shut down (i.e., stop providing power to the IC core module  412 ). As was the case described above with regard to the system  200  of  FIG. 2 , the command signal can be provided to either an enable input  418  to the main power supply  406  or to a feedback control loop input. The command line  416  is also coupled to a control input port  420  on the switch  402 . 
     Since the internal regulator  408  is not used during power on mode, the peripheral I/O power supply  410  can be disconnected from the regulator  408  during power on mode or power from the peripheral I/O power supply  410  otherwise disabled in order to improve the overall power efficiency of the system  400 . 
     Although the disclosed method and apparatus is described above in terms of various embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described. Thus, the breadth and scope of the claimed invention should not be limited by any of the above-described embodiments. 
     Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide examples of instances of the item in discussion, not an exhaustive or limiting list thereof; the terms “a” or “an” should be read as meaning “at least one,” “one or more” or the like; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future. 
     A group of items linked with the conjunction “and” should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as “and/or” unless expressly stated otherwise. Similarly, a group of items linked with the conjunction “or” should not be read as requiring mutual exclusivity among that group, but rather should also be read as “and/or” unless expressly stated otherwise. Furthermore, although items, elements or components of the disclosed method and apparatus may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated. 
     The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. The use of the term “module” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether control logic or other components, can be combined in a single package or separately maintained and can further be distributed in multiple groupings or packages or across multiple locations. 
     Additionally, the various embodiments set forth herein are described through the use of block diagrams, flow charts and other illustrations that illustrate examples of embodiments of the disclosed method and apparatus. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives can be implemented without confinement to the particular illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular architecture or configuration.