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`US007296164B2
`
`02) United States Patent
`Breen et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,296,164 B2
`Nov. 13, 2007
`
`(54) POWER MANAGEMENT SCHEME FOR
`EXTERNAL BATTERIES
`
`(75)
`
`Inventors: J ohn J. Breen, Harker Heights, TX
`(US); Jay L. Taylor, Georgetown, TX
`(US); Chris Young, Austin, TX (US)
`
`(73) Assignee: DeU Products L.P., Round Rock, TX
`(US)
`
`( *) Notice:
`
`Subject to any disclaimer, the tenn of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 463 days.
`
`(21) Appl. No.: 101963,679
`
`(22) Filed:
`
`Oct. 13, 2004
`
`(65)
`
`Prior Publication Data
`US 2006/0080051 Al
`Apr. 13, 2006
`
`(51)
`
`Int. CI.
`(2006.01)
`G06F 1100
`(2006.01)
`G06F 11110
`(52) U.S. CI ...................... .................. 713/300; 713/340
`(58) Field of C lassification Search ...... .......... 713/300,
`713/340
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`411995 Stewart
`
`5,404,546 A
`
`5,568,039 A
`5,818,200 A
`5,854,617 A *
`6,191,552 Bl
`6,262,562 B 1
`6,373,222 B2,.
`6,417,791 Bl,.
`6,452,362 Bl,.
`6,665,806 Bl,.
`7,085,944 Bl,.
`2001/0032321 Al*
`200210138775 Al*
`
`1011996
`10/ 1998
`1211998
`212001
`7/2001
`4/2002
`7/2002
`9/2002
`1212003
`8/2006
`10/2001
`9/2002
`
`Fernandez
`Cummings et al.
`Lee et al. ................... 345/ 102
`Kates et al.
`Cummings et al.
`Odaohhaxa .................. 320/ 116
`Benmouyal et al. . .. . . . . . 341/ l II
`Choo ............... .......... 320/ 116
`Shimizu ..................... 713/324
`Hamilton .......... .......... 713/320
`Nanoo et al. ............... 713/300
`Hauunond et al.
`.. .. .. ... 713/310
`
`* cited by examiner
`Primary Examiner- Thomas Lee
`Assistant Examiner- Ji H Bae
`(74) Attorney, Agent, or Finn- Haynes and Boone, LLP
`
`(57)
`
`ABSTRAC T
`
`In a method and system for managing power provided to a
`load, a power supply system includes a first power periph(cid:173)
`eral operable to receive and convert a first type of power to
`a second type of power. Also included in the power supply
`system is a second power peripheral operable to receive the
`second type of power and provide power to the load. A
`power event trigger device, which is included in the second
`power peripheral, is operable to introd uce a trigger signal in
`the power to the load. The trigger signal, which is introduced
`in response to receiving a change in the second type of
`power, is detected as a power event.
`
`18 Claims, S Drawing Sheets
`
`230
`
`210
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`250
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`I 270 I
`240
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`Apple 1004 - Page 1
`
`

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`
`AC-DC
`ADAPTER
`130
`
`115
`
`EXTERNAL
`BATTERY
`140
`
`120
`
`PORT ABLE IHS
`DEVICE
`101
`
`110
`
`FIG. 1 (PRIOR ART)
`
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`Apple 1004 - Page 2
`
`

`
`U.S. Patent
`
`Nov. 13, 2007
`
`Sheet 2 of S
`
`US 7,296,164 B2
`
`___________________________________________________________ _] ______________________ _
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`Apple 1004 - Page 3
`
`

`
`U.S. Patent
`
`Nov. 13, 2007
`
`Sheet 3 of S
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`US 7,296,164 B2
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`Apple 1004 - Page 4
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`RECEIVE FIRST VALUE OF AN INPUT
`510
`-
`
`RECEIVE DELAYED SECOND VALUE
`OF THE INPUT
`520
`-
`
`DETECT DIFFERENCE BETWEEN THE
`FIRST AND SECOND VALUES
`530
`-
`
`IDENTIFY OCCURENCE OF A POWER
`EVENT IN RESPONSE TO THE
`DIFFERENCE
`540
`-
`
`RECEIVE A THIRD VALUE AFTER THE
`PREDETERMINED TIME INTERVAL
`550
`-
`
`FIG. 5
`
`Apple 1004 - Page 5
`
`

`
`e •
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`/BUS 650
`
`PROCESSOR 610
`-
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`RAM MEMORY 620
`-
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`KEYBOARD 625
`-
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`1/0 DEVICES 640
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`DISPLAY DEVICE 605
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`HARD DISK DRIVE 630
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`- COMMUNICATION DEVICE 645
`....
`-
`
`INFORMATION HANDLING SYSTEM 600
`
`FIG. 6
`
`Apple 1004 - Page 6
`
`

`
`US 7,296,164 B2
`
`1
`POWER MANAGEMENT SCHEME FOR
`EXTERNAL BATTERIES
`
`BACKGROUND
`
`The present disclosure relates generally to information
`handling systems, and more particularly to techniques for
`managing power provided to portable information handling
`system components such as notebook computers, personal
`digital assistants, cellular phones and gaming/entertainment
`devices.
`As the value and use of information continues to increase,
`individuals and businesses seek additional ways to acquire,
`process and store information. One option available to users
`is information handling systems. An information handling
`system ('IHS') generally processes, compiles, stores, and/or
`communicates information or data for business, personal, or
`other purposes thereby allowing users to take advantage of
`the value of the information. Because technology and infor(cid:173)
`mation handling needs and requirements vary between dif(cid:173)
`ferent users or applications, information handling systems
`may also vary regarding what information is handled, how
`the information is handled, how much information is pro(cid:173)
`cessed, stored, or communicated, and how quickly and
`efficiently the information may be processed, stored, or
`communicated. The variations in information handling sys(cid:173)
`tems allow for information handling systems to be general or
`configured for a specific user or specific use such as financial
`transaction processing, airline reservations, enterprise data
`storage, or global communications. In addition, information 30
`handling systems may include a variety of hardware and
`software components that may be configured to process,
`store, and communicate information and may include one or
`more computer systems, data storage systems, and network(cid:173)
`ing systems.
`Various power management schemes exist to optimize
`battery life and thereby extend the operation of portable
`devices. For example, one or more batteries (including
`external and/or internal battery packs) may be configured to
`provide additional power to the IHS device. The IHS device 40
`may be placed in a battery-operated mode (BOM) of opera(cid:173)
`tion to conserve power by dimming its display panel.
`FIG. 1 illustrates a block diagram of a power supply
`system 100 providing power to a portable IHS device 101,
`according to prior art. The power supply system 100 45
`receives and converts an alternating current (AC) power
`input 110 to a direct current power (DC) output 120 to power
`a load such as the portable IHS device 101 or components
`thereof. The AC power input 110 is generally received from
`a 110-120 V, 60 Hertz or 220-230 V, 50 Hertz signal source 50
`from a wall outlet 105.
`In some configurations, the power supply system 100 may
`include an optional external battery 140 connected in series
`between the AC-DC adapter 130 and the IHS device 101. In
`this configuration, an AC-DC adapter 130 converts the AC
`voltage input 110 to a first DC voltage output 115 to provide
`DC power to a load. The external battery 140 receives the
`first DC voltage output 115 as an input and generates the DC
`voltage output 120 as an output.
`The external battery 140 typically functions as a pass(cid:173)
`through device. That is, the first DC voltage output 115 is
`substantially passed through as an output. Thus, the DC
`voltage output 120 is substantially the same as the first DC
`voltage output 115. A typical voltage range for the minimum
`and maximum values for the first DC voltage output 115 and 65
`the DC voltage output 120 is between 17.5 volts to 19.5
`volts. However, the specific voltage values for the first DC
`
`2
`voltage output 115 and the DC voltage output 120 may vary
`depending on the manufacturer.
`In some configurations, the DC voltage output 120 may be
`provided by external power sources such as an automobile's
`battery or an aircraft's DC power supply system. The DC
`voltage output 120 provided by these external power sources
`may be accepted as long as it is within the predetermined
`voltage range.
`Maintaining compatibility and co-ordination of operation
`10 between various mix-n-match components of the power
`supply system 100 is often a challenge for users as well as
`manufacturers. A mismatch of component specifications
`such as wattage, voltage and current may result in an unsafe
`operation. For example, a potential malfunction of the power
`15 supply system 100 may occur if the AC-DC adapter 130 is
`not rated to carry sufficient power to charge the external
`battery 140 as well as an internal battery 150, both of which
`may be operable to provide power to the IHS device 101.
`Faulty operation of the power supply system 100 may
`20 potentially result in unsafe and/or hazardous conditions. As
`another example, since the external battery 140 acts as
`pass-through device, the output of the external battery 140
`(assuming it has sufficient stored energy) remains substan(cid:173)
`tially the same, independent of its input. Thus, power events
`25 such as plugging and/or unplugging of the AC power input
`110 from the wall outlet 105 may go undetected, thereby
`resulting in a less-than-optimal performance of the portable
`IHS device 101.
`Therefore, a need exists to provide an efficient method
`and system for managing power provided to portable IHS
`devices. Additionally, a need exists to provide an improved
`technique to detect power events such availability of AC
`power without substantially increasing costs and/or reducing
`performance. Accordingly, it would be desirable to provide
`35 an improved power management technique for managing
`various components of a power supply system included in an
`information handling system absent the disadvantages found
`in the prior methods discussed above.
`
`SUMMARY
`
`The foregoing need is addressed by the teachings of the
`present disclosure, which relates to a system and method for
`managing power provided to an IHS. According to one
`embodiment, in a method and system for managing power
`provided to a load, a power supply system includes a first
`power peripheral operable to receive and convert a first type
`of power to a second type of power. Also included in the
`power supply system is a second power peripheral operable
`to receive the second type of power and provide power to the
`load. A power event trigger device, which is included in the
`second power peripheral, is operable to introduce a trigger
`signal in the power to the load. The trigger signal, which is
`introduced in response to receiving a change in the second
`55 type of power, is detected as a power event.
`In one embodiment, detecting a power event includes
`receiving a first value of an input indicative of an operating
`state of a power peripheral. A second value of the input
`indicative of a change in the state of the power peripheral is
`60 received. Receiving the second value is delayed relative to
`the receiving of the first value by a predetermined time
`interval. A difference between the first and second values is
`detected. An occurrence of a power event is identified in
`response to the difference.
`Several advantages are achieved by the method and
`system according to the illustrative embodiments presented
`herein. The embodiments advantageously provide for an
`
`Apple 1004 - Page 7
`
`

`
`US 7,296,164 B2
`
`3
`improved technique to generate power events in response to
`changes in operating state of one or more power peripherals
`included in a multi-peripheral power supply system. Thus,
`power events such as plugging or unplugging of AC power
`are detectable in a power supply system that includes a
`plurality of power peripherals. Triggering a power event
`advantageously enables BIOS to obtain updated power
`supply identifier (PSID) information for each of the power
`peripherals. This advantageously enables maintaining com(cid:173)
`patibility and co-ordination between the various power
`peripherals. In addition, it enables the IHS device to opti(cid:173)
`mize for peak-performance based on the PSID information.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 illustrates a block diagram of a power supply
`system providing power to a portable IHS.
`FIG. 2 illustrates a block diagram of an improved power
`supply system providing power to a load, according to an
`embodiment.
`FIG. 3 illustrates a pulse signal triggering a power event
`in a portable IHS, according to an embodiment.
`FIG. 4 illustrates a block diagram showing details of a
`second power peripheral of FIG. 2, according to an embodi(cid:173)
`ment.
`FIG. 5 illustrates a flow chart of a method for detecting a
`power event, according to an embodiment.
`FIG. 6 illustrates a block diagram of an information
`handling system having an improved power supply system,
`according to an embodiment.
`
`DETAILED DESCRIPTION
`
`Novel features believed characteristic of the present dis(cid:173)
`closure are set forth in the appended claims. The disclosure
`itself, however, as well as a preferred mode of use, various
`objectives and advantages thereof, will best be understood
`by reference to the following detailed description of an
`illustrative embodiment when read in conjunction with the
`accompanying drawings. The functionality of various cir(cid:173)
`cuits, devices or components described herein may be
`implemented as hardware (including discrete components,
`integrated circuits and systems-on-a-chip), firmware (in(cid:173)
`cluding application specific integrated circuits and program(cid:173)
`mable chips) and/or software or a combination thereof, 45
`depending on the application requirements.
`The following terminology may be useful in understand(cid:173)
`ing the present disclosure. It is to be understood that the
`terminology described herein is for the purpose of descrip(cid:173)
`tion and should not be regarded as limiting.
`Without having a PSID scheme identifying various power
`peripherals included in a power supply system, maintaining
`compatibility and co-ordination of operation between the
`various mix-n-match power peripherals is often a challenge
`for users as well as manufacturers. PSID information is 55
`typically scanned/updated by BIOS of an IHS device in
`response to a power event. In a power supply system having
`multiple power peripherals such as external batteries, the
`PSID information is not readily available or is not updated
`due to the pass through signal characteristics of the external 60
`battery power peripheral. As such, the IHS is often operated
`in a less-than-optimal performance mode. This problem may
`be addressed by an improved system to manage power
`provided to a load. In the improved system using PSID
`information, an output of the power peripheral is modified to 65
`generate a power event in the IHS device, thereby enabling
`BIOS to update the PSID information.
`
`4
`According to one embodiment, in a method and system
`for managing power provided to a load, a power supply
`system includes a first power peripheral operable to receive
`and convert a first type of power to a second type of power.
`Also included in the power supply system is a second power
`peripheral operable to receive the second type of power and
`provide power to the load. A power event trigger device,
`which is included in the second power peripheral, is oper(cid:173)
`able to introduce a trigger signal in the power to the load.
`10 The trigger signal, which is introduced in response to
`receiving a change in the second type of power, is detected
`as a power event.
`FIG. 2 illustrates a block diagram of an improved power
`supply system 200 providing power to the portable IHS
`15 device 101, according to an embodiment. The power supply
`system 200 includes one or more power peripherals, devices
`or components, which are inter-connected in an arrangement
`to provide power to a load device such as the portable IHS
`device 101. In one embodiment, some power peripherals are
`20 operable to receive and convert power from one form or type
`to another. In one embodiment, some power peripherals may
`function as pass through devices. That is, the power periph(cid:173)
`erals may pass through a signal received as an input to
`generate an output signal, which is substantially the same as
`25 the input signal. In this embodiment, the power peripherals
`may not convert power from one type to another.
`In the depicted embodiment, the power supply system 200
`includes a first power peripheral 230 and a second power
`peripheral 240 electrically coupled to provide power to a
`30 load, e.g., the portable IHS device 101. The first power
`peripheral 230 receives and converts an input signal 210,
`which is indicative of power of a first type, to an interme(cid:173)
`diate output signal 220, which is indicative of a power of a
`second type. In this embodiment, the first power peripheral
`35 230 is electrically coupled to the second power peripheral
`240 in a cascade arrangement. That is, the intermediate
`output signal 220, which is an output of the first power
`peripheral 230, is received as an input by the second power
`peripheral 240. The second power peripheral 240 generates
`40 an output signal 225, which provides power to the portable
`IHS device 101.
`In one embodiment, the first power peripheral 230 is an
`alternating current (AC) to a direct current (DC) (AC-DC)
`adapter device, which converts an AC power signal to a DC
`power signal. The input signal 210 may be an AC power
`input, which is generally received from a 120 V, 60 Hertz or
`220 V, 50 Hertz signal source from the wall outlet 105. The
`intermediate output 220 is a DC signal, which may vary
`within a predefined DC voltage range. For example, in one
`50 embodiment, the intermediate output 220 varies approxi(cid:173)
`mately between 17.5 volts and 19.6 volts.
`In one embodiment, the second power peripheral 240 is an
`external battery device. The external battery device is oper(cid:173)
`able receive a charge from the first power peripheral 230, to
`store the charge in rechargeable battery cells (not shown)
`and provide power to the portable IHS device 101. In this
`embodiment, the second power peripheral 240 functions as
`a pass through device for the DC power signal since the
`output signal 225 is substantially the same as the interme(cid:173)
`diate output 220. In one embodiment, like the intermediate
`output 220, the output 225 varies approximately between
`17.5 volts and 19.6 volts.
`To address the compatibility and co-ordination issue
`amongst one or more power peripherals (including the first
`and second power peripherals 230 and 240) present within
`the power supply system 200, some IHS manufacturers such
`as Dell Products, LP (Round Rock, Tex., USA) have pro-
`
`Apple 1004 - Page 8
`
`

`
`US 7,296,164 B2
`
`5
`vided a smart power supply system, which includes a power
`supply identification (PSID) scheme to identify the various
`types of power supply sources present. Information included
`in a PSID for each power peripheral may include attributes
`such as power type (e.g., AC or DC), wattage/voltage/ 5
`current rating, peripheral manufacturer, part number, coun-
`try of origin and similar others. Availability of such PSID
`information is advantageously used to match components
`and improve co-ordination between various power periph(cid:173)
`erals, thereby improving performance and increasing reli- 10
`ability and safety of the portable IHS device 101.
`For example, when a legacy AC-DC adapter without
`PSID (not shown but similar to the AC-DC adapter 130) is
`attached to the portable IHS device 101, information about
`the source of power is unknown to the device 101. As such, 15
`the BIOS sets the operation of the device 101 in a safe,
`battery optimized mode and disables the charging of the
`internal batteries (not shown). This may result in a less than
`optimal performance of the device 101. As another example,
`when an AC-DC adapter with PSID (e.g., first power periph- 20
`era! 230) is electrically coupled to the portable IHS device
`101, the source of power is known. The portable IHS device
`101 will operate at a pre-determined power level (identified
`by BIOS), based on the AC-DC adapter capacity identified
`in the PSID information for that peripheral. Since the power 25
`type and wattage rating is known the portable IHS device
`101 will advantageously enable charging of the internal
`batteries. An external battery with PSID (e.g., the second
`power peripheral 240) is connected in-between but will
`charge at no more than the BIOS identified power level (e.g., 30
`65 W).
`In order to determine its power source and optimize its
`performance, a controller 260 included within the portable
`IHS device 101 sends a request signal to one or more power
`peripherals over a bi-directional PSID line 250 to request 35
`PSID information. Each power peripheral, which is queried,
`sends a response signal over the PSID line 250. The response
`signal includes the requested PSID attribute information.
`For example, a response may include information such as
`'DC 150' or 'AC 100'. The DC 150 may indicate a DC type 40
`power source rated to operate at 150 watts, and the AC 100
`may indicate an AC type power source rated to operate at
`100 watts. In the depicted embodiment, the PSID informa(cid:173)
`tion provided by the first power peripheral 230 passes
`through the second power peripheral 240 and is delivered to 45
`the portable IHS device 101.
`Such requests or queries for PSID information are trig(cid:173)
`gered in response to power events such as plugging or
`unplugging of AC-DC adapter from the wall socket 105.
`Examples of power events may include power up or tran- 50
`sition to internal battery power from the external AC-DC
`adapter 130, or DC input voltage exceeding a threshold
`value. Thus, one such power event may be defined as a
`change in voltage value of the output 225. In one embodi(cid:173)
`ment, the controller 260 in the portable IHS device 101 55
`monitors the output 225 for a change in value. For example,
`a change in voltage of the output 225 from an initial 19.6
`volt level suggests a change in the power source. In response
`to the change in the output 225, the portable IHS device 101
`queries power peripherals for new/revised PSID informa- 60
`ti on. Requesting and reading of PSID information is accom(cid:173)
`plished in hardware, resulting in an interrupt to the controller
`260 whenever the DC voltage input (e.g., output 225)
`crosses the predetermined threshold value. Additional
`details of generating a power event are described in FIG. 3. 65
`Alternative techniques for identifying power supply may
`be utilized. As described earlier, PSID refers to a digital
`
`6
`identification encoded in semiconductor chip included in
`power peripherals. In one embodiment, the PSID may be a
`certain current or voltage level present on a sense line such
`as line 250. In one embodiment, PSID information may be
`superimposed on a signal or power line. Querying for PSID
`information may be a transient event appearing only during
`state transitions or may be present as a steady state signal.
`In one embodiment, PSID information may be obtained
`synchronously with a timing signal or asynchronously.
`Referring back to FIG. 2, the first and second power
`peripherals 230 and 240 may be connected to the device 101
`in various arrangements. In one embodiment, a first arrange(cid:173)
`ment may include the first power peripheral 230 receiving
`power from the wall outlet 105 being directly connected to
`the device 101. In this arrangement, the second peripheral
`240 is not present and PSID information of the first power
`peripheral 230 is provided to the controller 260 at the
`occurrence of a power event. In one embodiment, a second
`arrangement may include the second power peripheral 240
`having sufficient stored energy being directly connected to
`the device 101. In this arrangement, the first power periph(cid:173)
`eral 230 is not present and PSID information of the second
`power peripheral 240 is provided to the controller 260 at the
`occurrence of a power event. In one embodiment, the second
`arrangement may be changed to a third arrangement by
`connecting the first power peripheral 230 to provide DC
`power to the second power peripheral 240. The depicted
`embodiment is illustrative of the third arrangement. In the
`third arrangement, when the first power peripheral 230 is
`first plugged in the wall outlet 105 it generates the interme(cid:173)
`diate output 220 thereby causing a power event in the device
`101. The PSID information of the first power peripheral 230
`is passed through by the second power peripheral 240 to the
`controller 260.
`In one embodiment, a power event trigger component 270
`included in the second power peripheral 240 is operable to
`generate a change in the output 225 in response to a change
`in the intermediate output 220, thereby advantageously
`generating a power event detectable by the controller 260 of
`the portable IHS device 101. In one embodiment, the output
`225 is pulsed. That is, the output 225 is changed in the form
`of a pulse signal having a predetermined width. In one
`embodiment, the change in the output 225 is caused due to
`a change in the intermediate output 220, which in turn is
`caused as a result of plugging or unplugging of AC power
`input from the wall outlet 105.
`Referring to FIG. 3, a pulse signal triggering a power
`event is illustrated, according to an embodiment. At time t0
`302, the power supply system 200 is operating in a steady
`state and the intermediate output 220 and the output 225 are
`substantially the same. The output 225 has a first value 305,
`which is above a threshold value 330. At time t 1 304, the
`input 210 to the first power peripheral 230 is installed or
`removed. As a result, the intermediate output 220 changes.
`At time t2 306, the second power peripheral 240 detects the
`change in its input and pulses its output, thereby causing a
`change in the output 225. Now the output 225 has a second
`value 315, which is below the threshold value 330. That is,
`a change is caused by switching the output 225 to generate
`a pulse signal 310 having a predetermined width 320.
`Further detail of the second power peripheral 240, which
`includes a switching mechanism for the output 225, is
`described in FIG. 4.
`Referring back to FIG. 3, the pulse signal 310 causes the
`voltage of the output signal 225 to decrease below a thresh(cid:173)
`old voltage level 330 for a predetermined amount of time
`corresponding to the predetermined width 320. Thus, by
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`lowering the voltage level of the output 225 below a
`threshold level within the time duration of the predetermined
`width 320, the pulse signal 310 triggers an interrupt to the
`controller 260 and generates a power event.
`By advantageously having a power event occur when
`power peripherals are attached or detached, the controller
`260 is automatically triggered to read/update the PSID
`information to adjust power parameters and device perfor(cid:173)
`mance accordingly. The end of the predetermined time
`occurs at time t3 308. Between time t3 308 and time t4 309,
`the output 220 returns to a third value 325, which is the same
`as its previous voltage level (e.g., the first value 305). The
`specific threshold voltage level selected is dependent on the
`type of internal and/or external batteries included. In one
`embodiment, the threshold voltage level is 17 .5 volts. For
`certain types ofIHS devices such as PDA's, portable game
`devices and cell phones, the value of the threshold voltage
`may be lower. The predetermined width 320 is optimally
`selected so that it is not too large to cause an interruption in
`power provided to the portable IHS device 101 and is not too
`small to be undetected by the portable IHS device 101. In
`one embodiment, the predetermined width 320 is at least 150
`microseconds.
`FIG. 4 is a block diagram illustrating additional details of
`the second power peripheral 240, according to an embodi(cid:173)
`ment. The second power peripheral 240 receives the inter(cid:173)
`mediate output 220 and the PSID line 250 as input and
`generates the output 225 and the PSID line 250 as outputs.
`In one embodiment, a standard 3-pin coaxial connector (not
`shown) is used for inputs and outputs, with the center pin 30
`being used as the PSID line 250.
`The power event trigger component 270 includes a detec(cid:173)
`tion component 410 and switches 420 and 430. The detec(cid:173)
`tion component 410 is operable to monitor the intermediate
`output 220 for any changes. When the detection component 35
`410 detects a change, control signals 422 and 432 are sent
`to the switches 420 and 430 to open or close them. In one
`embodiment, only one control signal is sent to the switches
`420 and 430. In one embodiment, the switches 420 and 430
`are implemented using well-known field effect transistor 40
`(FET) devices.
`The switch 420 is operable to select one of the interme(cid:173)
`diate output 220 signal or an internal power source 440 of
`the external battery as the output 225 signal in response to
`receiving or not receiving the input 210. For example, when 45
`the input 210 is not received (for e.g., when AC power in
`unplugged from the wall outlet 105), the switch 420 is
`operable to connect the internal power source 440 of the
`external battery to the output 225. Similarly, the switch 430
`is operable to pass through the PSID line 250 received from 50
`the first power peripheral 230 or switch to an internal PSID
`line 450 (indicative of the second power peripheral 240) as
`the PSID line 250.
`In one embodiment, the switches 420 and 430 are oper(cid:173)
`able to generate the waveform described in FIG. 3. That is,
`the switch 420 is operable to the pulse the output 225 to
`generate the pulse signal 310, in response to the detection
`component 410 detecting a change. The switch 420 is turned
`on or off for a predetermined amount of time (indicated by
`the predetermined width 320). This causes the output 225 to 60
`decrease below the threshold level within the time duration
`of the predetermined width 320 and generate a power event
`in the controller 260 (not shown).
`FIG. 5 is a flow chart illustrating a method for detecting
`a power event, according to an embodiment. In step 510, a
`first value of an input indicative of an operating state of a
`power peripheral is received. For example, the controller
`
`8
`260 receives the output 225 having a first voltage value,
`which is above the threshold voltage level 330. In one
`embodiment, the first voltage value being above the thresh(cid:173)
`old voltage level 330 is indicative of an operating state of the
`first power peripheral 230 such as operating. In step 520, a
`second value of the input indicative of a change in the state
`of the power peripheral is received. Receiving the second
`value is delayed relative to the receiving of the first value by
`a predetermined time interval. For example, in response to
`10 a change in the operating state of the first power peripheral
`230, the output 225 is pulsed. The controller 260 receives a
`second voltage value of the output 225, which is below the
`threshold voltage level 330. The duration of the predeter(cid:173)
`mined time interval is the predetermined width 320. In step
`15 530, a difference between the first and second values is
`detected. That is, the controller 260 detects a difference in
`the output 225 from a first voltage value (exceeding the
`threshold level 330) to a second voltage value (below the
`threshold level 330). In step 540, occurrence of a power
`20 event is identified in response to the difference. In step 550,
`a third value of the input is received after the predetermined
`time interval, with the third value being substantially equal
`to the first value received. Various steps described above
`may be added, omitted, combined, altered, or performed in
`25 different orders.
`For purposes of this disclosure, an IHS may include any
`instrumentality or aggregate of instrumentalities operable to
`compute, classify, process, transmit, receive, retrieve, origi(cid:173)
`nate, switch, store, display, manifest, detect, record, repro(cid