United States Patent
`
`[19]
`
`[11] Patent Number:
`
`6,134,666
`
`De Nicolo
`
`[45] Date of Patent:
`
`Oct. 17, 2000
`
`US006134666A
`
`54
`
`POWER SUPERVISOR FOR ELECTRONIC
`MODULAR SYSTEM
`
`75
`
`Inventor: Maurilio Tazio De Nicolo, Saratoga,
`
`73
`
`21
`
`22
`
`51
`52
`58
`
`56
`
`Assignee: Cisco Technology, Inc., San Jose, Calif.
`
`Appl. No; 09/041,838
`
`Filed:
`
`Mar. 12, 1998
`
`_________________________________ __ G061; 1/26
`Int CL7
`713/300; 713/340; 713/330
`U.S. Cl.
`and of Search .............................. 710/2, 15, 16-19,
`710/101-103, 131, 132, 125-129, 713/300-340
`
`References Cited
`
`9/1998 Boatwright et al.
`5,802,379
`9/1998 Najerny ....... ..
`5,809,256
`11/1998 Chesavage
`5,834,925
`5545342 12/1998 Hayasaka ~ ~~ ~ ~ ~
`5,884,233
`3/1999 Brown . .. . . .. . . . .
`
`.
`
`713/324
`. 710/103
`323/272
`- ~ ~ ~- 713/340
`. . . . . .. 702/61
`
`Pr1-m‘”'Y Examiner_AYaZ R~ Sheikh
`Assistant Examz'ner—Raymond Phan
`Attorney, Agent, or Firm—D’Alessandro & Ritchie
`
`[57]
`
`ABSTRACT
`
`Each modular processor card of a modular electronic system
`°“‘“.°“‘°°:“P"T‘E°'“‘ definmg “,5 m‘;1’?1‘,‘11“m “urgent Or P‘.’V1“°r
`;:q‘;g§g;eI;§,,,, fccfizfflfgfi; Wogjmfifkye
`36:33:13;
`’
`P
`I
`V’
`_
`over a single conductor through a backplane by a power
`supervisor. The supervisor will determine the current/power
`requirements of a processor card while the card is substan-
`tially powered off. The supervisor may then weigh existing
`power supply resources of the modu ar electronic system
`with existin current’ ower demand and make a decision to
`11
`‘
`g
`fmth
`d .f
`-
`.
`I
`h‘ d .
`e car
`:1 0w power—up 0 .
`i
`su .l(.316l’1 over ea
`is
`available, or, alternatively, make a decision to deny power.
`up of the card .1f
`insufficieiit additional current/‘power
`resources are available. An optional message indicating the
`outcome of the decision can be transmitted to a user. If the
`supervisor elects to power up the card, a signal sent on the
`conductor connecting the card to the supervisor may be used
`to authorize the card to power up and control Circuitrv to
`cficct the power up
`'
`
`19 Claims, 2 Drawing Sheets
`
`U.S. PATENT DOCUMENTS
`.
`5/1989 Hemg et a1’ ””” "
`4’835’737
`o/1992 Balakrishman .
`5,122,091
`7/1993 Brown at al.
`5,226,120
`5,268,592 12/1993 Bellamy et al
`59386567
`1/1995 hen et at
`5,491,804
`2/1996 Heath et a],
`5,613,130
`3/1997 Tcng ct al.
`~
`5,532.-021
`5/1997 J'~“11I1i118S 91 ?11«
`5.~710.~931
`1/1998 Nakamum 9‘ “L -
`59726506
`3/1998 Wmd
`5,737,616
`4/1998 Watanabe .
`5,758,102
`5/1998 Carey ct al.
`5,790,873
`8/1998 Popper et al.
`5,796,185
`8/1998 Takata et al.
`
`,
`
`.
`
`364/900
`.. 307/475
`N 395/200
`307/43
`__ 395/700
`,, 395/275
`.. 713/310
`~~ 395/309
`~~ 713/310
`“ 307/147
`.. 713/340
`.. 710/103
`713/320
`......................... .. 307/140
`
`BACKPLANE
`
`Vcc
`
`POWER
`CIRCUIT
`SOFT START
`
`POWER
`SUPPLY #2
`
`POWER
`SUPPLY #N
`
`AMX
`Exhibit 1020-00001
`
`

`
`U.S. Patent
`
`00027:1LcO
`
`Sheet 1 of 2
`
`6,134,666
`
`Em_>>On_
`
`::om_o
`
`
`
`._.m<._.mtow
`
`m_z<#§o<m_
`
`mm>>On_
`
`2*>._n_n_Dw
`
`mm>>on_
`
`mu>._&:m
`
`m_m>>on_
`
`2%>._n_n_Dw
`
`AMX
`Exhibit 1020-00002
`
`

`
`U.S. Patent
`
`Oct. 17, 2000
`
`Sheet 2 of2
`
`6,134,666
`
`ENABLE
`
`FIG. 2
`
`POWER
`SUPERVISOR
`
`BACKPLANE
`
`POWER
`SUPERVISOR
`
`PRESTART
`AREA
`
`MODULE
`
`AMX
`Exhibit 1020-00003
`
`

`
`6,134,666
`
`1
`POWER SUPERVISOR FOR ELECTRONIC
`MODULAR SYSTEM
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention is directed to a method and appa-
`ratus which permit a power supervisor in a multi-card
`modular electronic system to turn on or olf power to a given
`modular processor card based upon considerations of the
`power needed by the card and the power resources available
`to the modular electronic system.
`2. The Background Art
`Multi—card modular electronic systems are common in the
`computer industry. Typically such systems comprise a back
`plane having a plurality of connectors to which a number of
`line cards or processor cards are connected. Processor cards
`may perform any of a number of functions as well known to
`those of ordinary skill in the art. The back plane provides
`electrical interconnections to the processor cards, such as ~
`data, power, ground and signalling. Such systems usually
`include at least one supervisor module which may be on one
`of the processor cards or may be permanently connected to
`the back plane. Supervisor modules are commonly used to
`detect errors and report conditions to a user.
`It is desirable to build modular systems which provide for
`future expansion while providing a relatively low entry cost.
`In systems employing processor cards whicl1 consume sig-
`nificant quantities of power, such as those embodying one or
`more microprocessors, or equivalently power hungry
`devices, it may be desirable to provide for modular power
`supplies which may be added or changed as power require-
`ments increase with the addition of more processor cards or
`the substitution of higher power consumption processor
`cards for lower power consumption processor cards.
`I11 such systems,
`it
`is frequently a problem that an
`individual responsible for such systems may inadvertently
`place too high a power demand upon a particular power
`supply configuration of such a system through the addition
`of a particular processor card to a previously functioning
`system. The consequences can vary from a simple sh11t down
`or an inability to start up to equipment damage.Accordingly,
`it would be desirable to provide a method and apparatus
`which could simply protect such systems from the conse-
`quences of errors n1ade by inadvertently overlooking avail-
`able power supply resources in such modular electronic
`systems.
`As back plane conductor lines are a relatively scarce and
`expensive resource in such systems, it would also be desir-
`able to implement such method and apparatus in a manner
`which makes a minimum use of such scarce resources.
`
`SUMMARY OF THE INVENTION
`
`Each modular processor card of a modular electronic ..
`system carries a component defining its maximum current or
`power requirements. The component, which may be a
`resistor, capacitor, serial access n1en1ory, or the like,
`is
`accessible over a single conductor through a backplane by a
`power supervisor. The supervisor will determine the current/’
`power requirements of a processor card while the card is
`substantially powered olf. The supervisor may then weigh
`existing power supply resources of the modular electronic
`system with existing current/power demand and make a
`decision to allow power—up of the card if sufficient overhead
`is available, or, alternatively, make a decision to deny
`power-up of the card if insu lcient additional current/power
`
`2
`resources are available. An optional message indicating the
`outcome of the decision can be transmitted to a user. If the
`supervisor elects to power up the card, a signal sent on the
`co11ductor connecting the card to the supervisor may be used
`to authorize the card to power up and control circuitry to
`elfect the power up.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is an electrical schematic diagram of a presently
`preferred embodiment of the present invention.
`FIG. 2 is an electrical schematic diagram of a typical
`power soft start circuit for use in conjunction with a pres-
`ently preferred embodiment of the present invention.
`FIG. 3 is a system block diagram of an alternative
`preferred embodiment of the present invention.
`FIG. 4 is a system block diagram of another alternative
`preferred embodiment of the present invention.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`Those of ordinary skill in the art will realize that the
`following description of the present invention is illustrative
`only and is not intended to be in any way limiting. Other
`embodiments of the invention will readily suggest them-
`selves to such skilled persons from an examination of the
`within disclosure.
`
`Turning to FIG. 1, a presently preferred embodiment of
`the present
`invention is shown. In accordance with the
`present invention, a modular electronic system 10, such as
`computer communications equipment, has a backplane cori-
`nector strip 12 which provides electrical interconnections
`among a plurality of electronic modules or cards which are
`electrically attached to it (e.g., plugged into it). The inven-
`tion will work with one or more electronic modules.
`
`In such modular electronic systems, one or more power
`supplies may be provided having certain power or current
`delivery capabilities. To render such systems more flexible,
`a plurality of positions can be provided into which such
`power supplies may be installed. The problem is that given
`a very flexible level of power supply resources and a very
`flexible level of power demand posed by the electronic
`modules which may be attached to the backplane,
`the
`modular electronic system now must monitor both its
`resources and its power demand to insure that there is no
`shortfall of power which might cause system unreliability or
`failure.
`
`In accordance with a presently preferred embodiment of
`the present invention, a power supervisor 14 is provided.
`The power supervisor 14 has a communications li11k 16 to
`one or more power supplies 18, 20, 22 which communicates
`information defining available power resources to a micro-
`processor 24 of power supervisor 14. This communication
`may be carried out in any of a number of ways.
`According to a presently preferred embodiment of the
`present invention, each power supply module 18, 20, 22 may
`have stored in it a relatively permanent memory having a
`three (or more) hit identification code that can be read by
`power supervisor 14 over communications link 16. Each
`power supply 18, 20, 22 will have its proper predefined
`identification code set at the time of its manufacture to a
`value unique for its model and/or indicative of its maximum
`ability to supply power or current. In typical use the power
`supervisor 14 will read the identification code at power up,
`and/or at any time that the power supply module 18, 20, 22
`is inserted into or attached to power supervisor 14. Power
`
`AMX
`Exhibit 1020-00004
`
`

`
`6,134,666
`
`3
`supervisor 14 then takes the identification code for the
`power supply module, and if necessary, looks up in a table
`associated with power supervisor 14 the identification code
`in order to determine a power output value for the power
`supply.
`In an alternative preferred embodiment, in order to pro-
`vide more information without relying on software tables
`embedded in power supervisor 14, to serial electronically
`erasable programmable read only memory (EEPROM) is
`used in each power supply module 18, 20, 22. The serial
`EEPROM is preferably programmed at the time of manu-
`facture of the power supply module with information apro-
`pos of the power supply module, e.g., output voltages, input
`voltages, current levels, operating characteristics, model,
`type, serial number, manufacturer, and the like. This infor-
`mation is then read at power up, or at insertion or attachment
`of the power supply module to power supervisor 14 so that
`power supervisor 14 is fully advised of the operating char-
`acteristics of the power supply modules attached to it and
`can act on that information. Abenefit of this latter approach ~
`is that new power supply modules can be created after power
`supervisor 14 is fixed and installed and power supervisor 14
`can still make full use of the information encoded in the
`serial EEPROM without any need for an upgrade or soft-
`ware update to the power supervisor. Other non-volatile
`memory devices could also be used instead of the serial
`EEPROM discussed above, as would be understood by those
`of ordinary skill in the art. Preferably such devices would
`use a single bit data path in order to minimize connections
`between power supervisor 14 and power supply modules 18,
`20, 22.
`Electronic module 26 attaches to backplane 12. Each
`electronic module will have a particular power requirement.
`Obviously the power demand of module 26 will fluctuate
`depending upon what it is doing at a particular moment, but
`it wfll have a known maximum power requirement or
`demand which can be thought of as the worst case power
`requirement. It is this known maximum power requirement
`that must be communicated to power supervisor 14.
`In accordance with a presently preferred embodiment of
`the present invention, the maximum power requirement is
`communicated by an analog voltage signal on a query
`conductor 28 passing from electronic module 26 through
`backplane 12 to power supervisor 14. Query conductor 28 is
`connected to a first source of a voltage, such as Vcc 30
`through resistor R1 which may be a 100 ohm resistor.
`Analog to digital converter 32 converts the voltage on query
`conductor 28 to a digital value for use by programmed
`microprocessor 24. A component, such as an impedance
`element, which may be a resistor, Rset 34, disposed between
`query conductor and a source of a second voltage 36, such
`as ground, encodes a voltage signal on query conductor 28,
`the voltage being a function of the resistance of resistor 34.
`For example, Rset 34 could be 25 ohms if power demand of g
`the module is 5 amperes, 50 ohms if 10 amperes, 75 ohms
`if 15 amperes, and 100 ohms if 20 amperes.
`The voltage drop between Vcc 30 and query line 28
`through R1 is selected to be su Icient to prevent current flow
`through zener diode D1, thus isolating the portion of the
`circuitry of module 26 connected to the anode 38 of zener
`diode from query line 28.
`If microprocessor 24 decides that suflicient power
`resources are available to permit module 26 to be turned on
`with its now known maximum power requirement,
`then
`microprocessor 24 sends a signal “PWRUP” on line 40 to a
`switch shown here as transistor Q1. The presence of the
`
`p
`
`4
`PWRUP signal on the control gate of transistor Q1 permits
`current to How through Q1 from Vcc to query line 28. This
`voltage, not dropping through resistor R1, will cause a
`higher voltage to obtain on query line 28. This voltage will
`be selected to be above the threshold of zener diode D1. In
`turn, current will flow through resistors R2 and R3 providing
`a signal on a control gate of transistor Q2 which assumes the
`role of a switch. When this current flows, Q2 will turn on and
`provide an ENABLE signal on line 42 to power circuit soft
`start 44.
`
`Power circuit soft start 44 operates in a conventional
`n1am1er, such as that shown in FIG. 2, to slowly turn on
`power available on line 46 and apply it
`to the power
`consuming circuitry of module 26 denoted “A” while the
`ENABLE signal is asserted on line 42. Note that “A” will be
`provided with a slightly lower voltage “V” than Vcc (V+e)
`available at backplane 12 due to the voltage drop (e) through
`transistor Q3 which is preferably a power MOSFET. Cl is
`preferably 0.1 uF and C2 and C3 are filter capacitors chosen
`based upon the application. The circuit shown in FIG. 2 is
`for reference only. An actual implementation would likely
`contain additional components needed to control the power
`slope as known to those of ordinary skill in the art.
`Those of ordinary skill in the art: will realize that other
`components may be used to encode the maximum power
`demand of module 26 on query conductor 28. For example,
`capacitors, power supplies, and other elements having
`unique electrical characteristics capable of being read
`remotely over a single conductor could be used. Turning to
`FIGS. 3 and 4, a more sophisticated implementation of the
`present invention is shown. In FIG. 3 the component is a
`communications register 48. Power supervisor 50 com111u-
`nicates with communications register 48 over query line 52
`which passes through backplane 54. Module 56 also com-
`municates with communications register 48 over line 58.
`Power supervisor 52 may send messages to module 56 via
`communications register 48 which is preferably a one-bit
`wide data communications path. Communications register
`48 is preferably a serial register or serial access memory
`device or the like. Communications from power supervisor
`50 to module 56 may include, for example, messages along
`the lines of “send your maximum power requirement”,
`“send your model type” (so that the power supervisor could
`determine from its pre—programmed memory what the maxi-
`mum power demand is), “go ahead and start up”, “do not
`start—maximum power exceeded”, and the like. Power may
`be provided to register 48 and module 56 during this
`pre—start period via line 60 connected to Vcc 62 through
`backplane 54 as these devices typically require some mini-
`mal amount of power in order to function. This minimal
`power, however, is negligible relative to the full maximum
`power requirement of the module 56.
`Asoft-start circuit along the lines of FIG. 2 (or equivalent)
`would preferably be incorporated into Module 56. If a “go
`ahead and start up” signal is received by module 56, the
`soft-start circuit would be activated to bring the module on
`line.
`FIG. 4 shows a refinement of the embodiment of FIG. 3.
`In FIG. 4, power supervisor 64 communicates with module
`66 over a query line 68 which passes through backplane 70.
`Module 66 is provided with a prestart area 72. Prestart area
`72 is provided with power over line 74 from a backplane
`connection to Vcc 76. Prestart area 72’s circuitry is powered
`by connection to line 74, but
`the bulk of the power-
`consuming circuitry of module 66 remains unpowered until
`the prestart area 72 receives instructions from power super-
`visor 64 to turn on module 66. The prestart area 72 may
`
`AMX
`Exhibit 1020-00005
`
`

`
`6,134,666
`
`5
`carry on extensive communications with power supervisor
`64 and power supervisor 64 may require information in
`addition to maximum power req11irement—for example, a
`password could be required, or a particular range of serial
`numbers could be required. The power supervisor 64 could
`be programmed to disallow the power up of unauthorized
`devices or devices known to be incompatible with the
`particular modular electronic system in question. Some of
`these functions could also be included in the FIG. 3 embodi-
`ment.
`
`In accordance with the various preferred embodiments of
`present invention the connections to a plurality of modules
`could be carried out with a plurality of query lines, each with
`a connection to the power supervisor, or with a single
`conductor connection to the power supervisor multiplexed to
`the plurality of modules in a conventional manner.
`It is intended that the system provided herein would be
`capable of “hot swapping” of module cards and/or power
`supply modules.
`In this manner,
`the system would be
`operating and an additional card would be plugged into a slot
`on the backplane. The power supervisor would detect the “
`insertion of the card in a conventional manner and would
`query the module to determine if turning it on would exceed
`power resources available to the system. The system could
`also work without a “hot swapping” capability.
`The term “power” has been used herein but is meant to
`include current level at a particular voltage, a combined
`power demand comprising a multiple voltage power demand
`at various currents, and the like, depending upon the system
`characteristics. For example, if all power used by the module
`is at 3.3 V, then the only variable is current. However, if the
`module uses 3.3 V power as well as 5 V power, those of
`ordinary skill in the art will readily see how the system
`described above could easily be expanded to cover a multi-
`voltage system. While a multiplexing scheme, for example,
`could be used to scan for a nu111ber of different voltage
`requirements, or different voltage/current combinations
`could be encoded with a single component, multiple query
`conductors could also be used, if more convenient.
`The power supervisor may itself be a module plugged into
`the backplane, or
`it may assume another physical
`embodiment, as long as it has the required connections to the
`backplane conductors.
`Alternative Embodiments
`Although illustrative presently preferred embodiments
`and applications of this invention are shown and described
`herein, many variatio11s and modifications are possible
`which remain within the concept, scope, and spirit of the
`invention, and these variations would become clear to those
`of skill
`in the art after perusal of this application. The
`invention, therefore, is not to be limited except in the spirit
`of the appended claims.
`What is claimed is:
`1. A power management system
`a backplane to which a modular component may be H
`connected, said modular component having an associ-
`ated known maximum power demand;
`a query line having a first end and a second end connected
`together through said backplane, said first end adapted
`to connected to said modular component;
`a power supervisor attached to said backplane and to said
`second end, said power supervisor adapted to query
`said query line and to receive therefrom an associated
`known maximum power demand of said modular
`component,
`wherein said power supervisor includes a first voltage
`source coupled to said query line through a first
`
`6
`resistance, wherein said power supervisor senses said
`associated known maximum power demand by sensing
`a voltage level on said query line, wherein said power
`supervisor causes a selected voltage level to be applied
`to said query line to cause said modular component to
`fully power up, wherein said power supervisor gener-
`ates a power up signal which is sent over a line to a
`switch having a first state and a second state, said
`switch allowing power to flow onto said query line
`when in said first state and not allowing power to flow
`onto said query line when in said second state, said
`switch being in said second state in the absence of said
`power up signal and said switch being in said first state
`in the presence of said power up signal.
`2. A power management system according to claim 1
`wherein said switch includes a transistor having a control
`gate connected to said line.
`3. A power management system according to claim 2
`wherein said power supervisor further includes a digitizing
`element coupled to said query line for providing a digital
`representation of said voltage level to said power supervisor.
`4. A power management system for a modular electronic
`system comprising:
`a backplane to which a modular component may be
`connected, said modular component having an associ-
`ated known maximum power demand;
`a query line having a first end and a second end connected
`together through said backplane, said first end adapted
`to connected to said modular component;
`a power supervisor attached to said backplane and to said
`second end, said power supervisor adapted to query
`said query line and to receive therefrom an associated
`known maximum power demand of said modular com-
`ponent;
`a source of first information indicative of available power
`resources of the modular electronic system, and
`a source of second information indicative of existing
`power resource utilization of the modular electronic
`system, wherein
`the power management system is adapted to compare said
`first
`information, said second information and said
`associated known power demand of said modular com-
`ponent to determine if su icient power resources exist
`to successfully fully power up said modular compo-
`nent.
`
`5. A power management system for a modular electronic
`system comprising:
`a backplane to which a modular component may be
`connected, said modular component having an associ-
`ated known maximum power demand;
`a query line having a first end and a second end connected
`together through said backplane, said first end adapted
`to connected to said modular component;
`a power supervisor attached to said backplane and to said
`second end, said power supervisor adapted to query
`said query line and to receive therefrom an associated
`known maximum power demand of said modular com-
`ponent; and
`a source of first information indicative of excess power
`resources of the modular electronic system, wherein
`the power management system adapted to compare said
`information and said associated known power demand
`of said modular component to determine if sufficient
`power resources exist to successfully fully power up
`said modular component.
`
`AMX
`Exhibit 1020-00006
`
`

`
`6,134,666
`
`7
`6. A power management system according to claim 5
`wherein said power supervisor includes a first voltage source
`coupled to said query line through a first resistance.
`7. A power management system according to claim 6
`wherein said power supervisor senses said associated known 5
`maximum power demand by sensing a voltage level on said
`query line.
`8. A power management system according to claim 7
`wherein said power supervisor causes a selected voltage
`level to be applied to said query line to cause said modular
`component to fully power up.
`9. A power management system according to claim 8
`wherein said power supervisor generates a power up signa
`which is sent over a line to a switch having a first state anc
`a second state, said switch allowing power to flow onto saic
`query line when in said first state and not allowing power to
`flow onto said query line when in said second state, saic
`switch being in said second state in the absence of saic
`power up signal and said switch being in said first state in the
`presence of said power up signal.
`10. A power management system according to claim 9 ~
`wherein said switch includes a transistor having a contro
`gate connected to said line.
`11. A power management system according to claim 8
`wherein said power supervisor further includes a digitizing
`element coupled to said query line for providing a digita
`representation of said voltage level to said power supervisor.
`12. An electronic modular component for connection to a
`modular electronic system including a backplane and a
`power supervisor, said power supervisor having information
`indicative of remaining uncommitted electronic power
`resources of said electronic system, said modular component
`comprising:
`a query line conductor having a first end and a second end,
`said first end connected to said backplane, said second
`end connected to a query node;
`a resistor having a first terminal oonnected to said query
`node and a second terminal connected to a source of a
`first voltage, said resistor’s resistance indicative of a
`known maximum power demand of the electronic
`modular component, said resistor being able to be
`queried by the power supervisor while the electronic
`modular component is attached to the backplane; and
`a zener diode having a breakdown voltage set to a second
`voltage, said zener diode having a cathode connected to
`said query node and an anode operatively connected to
`a switch, said switch having a first state and a second
`state, said switch transmitting an enable signal to a
`power soft start circuit of the electronic modular com-
`ponent when in said first state and not transmitting said
`enable signal when in said second state, said switch
`being in said second state in the absence of substantial
`current flow through said zener diode.
`13. A modular electronic system comprising:
`a backplane to which an electronic module having a H
`known maximum power requirement is attached;
`a power supervisor connected to said backplane;
`a query conductor coupling a query node of said elec-
`tronic module to said power supervisor through said
`backplane;
`encoder associated with said electronic module for pro-
`viding signals to said power supervisor which are
`indicative of said maximum power requirement,
`wherein said encoding means comprises an electrical
`impedance element, wherein an electrical impedance is
`preselected to correlate with said known maximum
`power requirement; and
`
`8
`decoder associated with said power supervisor for decod-
`ing said signals to determine said maximum power
`requirement.
`14. A modular electronic system according to claim 13
`wherein said electrical impedance element is a first resistor.
`15. A modular electronic system according to claim 14
`wherein said signals which are indicative of said maximum
`power requirement are voltage signals produced by passing
`an electric current through said first resistor.
`16. A modular electronic system according to claim 15
`wherein said decoder comprises a programmed micropro-
`cessor.
`
`17. A modular electronic system, comprising:
`a backplane to which an electronic module having a
`known maximum power requirement is attached;
`a power supervisor connected to said backplane;
`a query line conductor coupling a query node of said
`electronic module to said power supervisor through
`said backplane;
`encoding means associated with said electronic module
`for providing signals to said power supervisor which
`are indicative of said maximum power requirement,
`said encoding means comprising a first resistor having
`a resistance preselected to correlate with said known
`maximum power requirement; and
`a programmed microprocessor associated with said power
`supervisor for decoding said signals to determine said
`maximum power requirement, said signals being volt-
`age signals produced by passing an electric current
`through said first
`resistor; said first resistor being
`connected between said query node and a source of a
`first voltage, said signals carried over a query conduc-
`tor passing from said query node through said back-
`plane and coupled through a second resistor to a source
`of a second voltage.
`18. A modular electronic system according to claim [7
`wherein a zener diode having a breakdown voltage set to a
`third voltage intermediate said first voltage and said second
`voltage has a cathode connected to said query node and an
`anode operatively connected to a switch, said switch having
`a first state and a second state, said switch transmitting an
`enable signal to a power soft start circuit of the electronic
`module when in said first state and not transmitting said
`enable signal when in said second state, said switch being in
`said second state in the absence of substantial current flow
`through said zener diode.
`19. A method for authorizing the power up of a module
`connected to a backplane of a modular electronic system,
`said modular electronic system including a power
`supervisor, said method comprising the steps of:
`encoding information indicative of a maximum power
`requirement of the module;
`sending said encoded information over a conductor
`through the backplane to the power supervisor;
`decoding said information;
`applying said information to the power supervisor;
`determining if said maximum power requirement of the
`module, in addition to other power requirements of the
`modular electronic system, exceeds available power
`resources of the modular electronic system; and
`sending an authorization signal to the module if said
`determining step indicates that adequate power is avail-
`able to power up the module.
`
`AMX
`Exhibit 1020-00007
`
`

`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`CERTIFICATE OF CORRECTION
`
`PATENT NO.
`DATED
`
`INVENTOR(S)
`
`: 6,134,666
`: October 17, 2000
`: Maurilio Tazio De Nicolo
`
`It is certified that error appears in the above-identified patent and that said Letters Patent is
`hereby corrected as shown below:
`
`Title page.
`Item [57], ABSTRACT,
`Replace "Circuitry" with —— circuitry
`
`Column 1
`
`Lines 19, 24 and 48, replace "back plane" with —— backplane
`
`Column 4
`
`Line 24, after "art" dclctc ".".
`
`Column 5
`
`Line 12, before "present" insert —— the ——; and after "invention" insert —— ,
`Line 54, after "system" insert —— for a modular electronic system, comprising:
`Line 60, replace "connected" with —— connect
`
`Column 6
`
`Lines 23 and 47, after "system" insert —— ,
`Lines 29 and 53, replace "connected" with —— connect
`
`Column 7
`
`Line 24, replace "8" with —— 10
`
`Column 8
`
`Line 1, before "decoder" insert —— a
`
`Signed and Sealed this
`
`Eleventh Day of June, 2002
`
`Arresting Oflicer
`
`JAMES E. ROGAN
`Director ofthe United States Patent and Trademark Office
`
`AMX
`Exhibit 1020-00008