UNITED STATES PATENT AND TRADEMARK OFFICE
`
`
`
`
`
`
`
`
`
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`SEMICONDUCTOR COMPONENTS INDUSTRIES, LLC d/b/a
`ON SEMICONDUCTOR
`Petitioner
`
`v.
`
`POWER INTEGRATIONS, INC.
`Patent Owner
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Case IPR2016-01600
`Patent No. 7,834,605
`
`
`
`
`
`
`
`
`
`PATENT OWNERS’
`PRELIMINARY RESPONSE
`
`
`
`
`
`
`
`
`
`
`
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`SEMICONDUCTOR COMPONENTS INDUSTRIES, LLC d/b/a
`ON SEMICONDUCTOR
`Petitioner
`
`v.
`
`POWER INTEGRATIONS, INC.
`Patent Owner
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Case IPR2016-01600
`Patent No. 7,834,605
`
`
`
`
`
`
`
`
`
`PATENT OWNERS’
`PRELIMINARY RESPONSE
`
`
`
`
`
`
`I.
`
`II.
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`
`TABLE OF CONTENTS
`
`INTRODUCTION ........................................................................................... 1
`
`PETITIONER IS TIME BARRED FROM SEEKING INTER PARTES
`
`REVIEW. ......................................................................................................... 4
`
`III. THE ‘605 PATENTED INVENTION AND TECHNICAL BACKGROUND
`
` ....................................................................................................................... 11
`
`A.
`
`Technology Background: “Switch-mode” power supplies and the cycle-by-
`
`cycle current limit .......................................................................................... 11
`
`B.
`
`The Invention of the ‘605 Patent ................................................................... 20
`
`IV. CLAIM CONSTRUCTION .......................................................................... 28
`
`A.
`
`Claim 1 requires a current limit threshold that increases in a detectable
`
`manner during a single given switch on-time ................................................ 29
`
`V. GROUND 1 FAILS BECAUSE DE SARTE FAILS TO DISCLOSE AN
`
`INCREASING CURRENT LIMIT THRESHOLD DURING ANY GIVEN
`
`SWITCH ON-TIME ...................................................................................... 36
`
`VI. GROUND 1 ALSO FAILS BECAUSE DE SARTE DOES NOT
`
`DISCLOSE A CONTROL CIRCUIT THAT CAN RESPOND TO BOTH
`
`OF THE RECITED INPUTS DURING ANY GIVEN SWITCH ON-TIME
`
` ....................................................................................................................... 44
`
`
`
`i
`
`
`
`
`VII. CONCLUSION .............................................................................................. 49
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`
`
`ii
`
`
`
`
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`LIST OF EXHIBITS
`
`PI 2002
`
`PI 2003
`
`PI 2004
`PI 2005
`
`Exhibit No. Description
`PI 2001
`Copy of Agreement and Plan of Merger as between Fairchild and
`ON Semiconductor filed with the SEC
`Press release related to merger between Fairchild and ON
`Semiconductor
`Power Integrations, Inc., v. Fairchild Semiconductor International,
`Inc. et al., Case No. 08-309-LPS (D. Del.), Dkt. No. 401
`RESERVED
`Article about completion of merger between ON Semiconductor
`and Fairchild
`Power Integrations, Inc., v. Fairchild Semiconductor International,
`Inc. et al., Case No. 08-309-LPS (D. Del.), Dkt. No. 731
`Confidentiality Agreement, dated September 14, 2015
`“XYZs of Oscilloscopes,” Tektronix, Inc., © 2000
`“Oscilloscope Fundamentals,” Tektronix, Inc., © 2009
`
`PI 2006
`
`PI 2007
`PI 2008
`PI 2009
`
`
`
`
`iii
`
`
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`TABLE OF AUTHORITIES
`
`
`
`CASES
`
`Aruze Gaming Macau, Ltd. v. MGT Gaming, Inc., Case IPR2014-01288, 2015 WL
`780607, at *5 (PTAB Feb. 20, 2015) .......................................................... 7, 8
`
`
`In re Morris, 127 F.3d 1048, 1054-55 (Fed. Cir. 1997) .......................................... 29
`
`Int’l Nutrition Co. v. Horphag Research, Ltd., 220 F.3d 1325, 1329 (Fed. Cir.
`
`2000) ................................................................................................................ 6
`
`Nestle USA, Inc. v. Steuben Foods, Inc., Case IPR2015-00195 ................................ 5
`
`Pall Corp. v. Fisher Scientific Co., 962 F. Supp. 210 (D. Mass. 1997) .................... 6
`
`Power Integrations, Inc., v. Fairchild Semiconductor International, Inc. et al.,
`Case No. 08-309-LPS (D. Del.) ................................................................... 1, 7
`
`
`Synopsys, Inc. v. Mentor Graphics Corp ................................................................... 9
`
`VMware, Inc. v. Good Technology Software, Inc., Case IPR2015-00027 ............ 5, 9
`
`
`
`OTHER AUTHORITIES
`37 C.F.R. § 42.104(a) ................................................................................................. 9
`Office Patent Trial Practice Guide, 77 Fed. Reg. 48,756, 48,759 (Aug. 14, 2012)4, 10
`
`
`
`
`
`
`iv
`
`
`
`
`
`I.
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`INTRODUCTION
`Pursuant to 37 C.F.R. § 42.107(a), patent owner Power Integrations, Inc.
`
`(“Patent Owner”) submits this Preliminary Response in response to the Petition for
`
`Inter Partes Review (“IPR”) of U.S. Patent No. 7,834,605 (“the ‘605 patent”) filed
`
`by Semiconductor Components Industries, LLC d/b/a ON Semiconductor
`
`(“Petitioner” or “ON Semiconductor”).
`
`As a preliminary matter, institution must be denied because Petitioner ON
`
`Semiconductor is time barred from seeking inter partes review under 35 U.S.C. §
`
`315(b). On November 18, 2015, Petitioner entered into an Agreement and Plan of
`
`Merger with Fairchild Semiconductor International, Inc. (“Fairchild”). See Ex.
`
`2001 (copy of Agreement and Plan of Merger as filed with the SEC); Ex. 2002
`
`(press release). Fairchild is barred under 35 U.S.C. § 315(b) because it was served
`
`with a complaint for infringement of the ‘605 patent on June 6, 2011, in Power
`
`Integrations, Inc., v. Fairchild Semiconductor International, Inc. et al., Case No.
`
`08-309-LPS (D. Del.) (“Fairchild District Court Action”). See Ex. 2003 (Dkt. No.
`
`401). Since that time, on Sept. 19, 2016, that merger was completed and Petitioner
`
`has conceded that Fairchild is a real party in interest as of Sept. 19, 2016. See
`
`Paper 6 at 3.
`
`Petitioner has also failed to meet its burden of showing a reasonable
`
`likelihood that the Petitioner would prevail with respect to any claim challenged in
`
`
`
`1
`
`
`
`
`the Petition. Specifically, Petitioner’s sole ground 1 must be denied for at least
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`two reasons.
`
`First, as discussed in Section V below, Ground 1 is an anticipation
`
`contention relying on the de Sarte reference. The de Sarte reference does not
`
`teach, either expressly or inherently, “a comparator . . . having a second input
`
`coupled to receive a variable current limit threshold that increases during the on
`
`time of the switch,” as required by sole independent claim 1. In particular, under
`
`the broadest reasonable interpretation of “a variable current limit threshold that
`
`increases during the on time of the switch,” the variable threshold must be a
`
`current limit threshold that increases in a detectable manner during a single given
`
`switch on-time. See Section IV (Claim Construction), infra. In contrast, the de
`
`Sarte reference discloses a power supply regulator with a special startup mode.
`
`The de Sarte reference discloses a current limit used during this startup period that
`
`is sourced from a 1Hz oscillator, while the switch operates based on a 20kHz
`
`oscillator. Thus, the switch will have 20,000 on-times for every period of the low
`
`frequency startup current limit. In any single given switch on-time the current
`
`limit will not increase in a detectable manner and will function as a fixed current
`
`limit. The de Sarte current limit is not within the literal scope of the ‘605 patent
`
`claims and would not accomplish the goals of the ‘605 patented invention.
`
`
`
`2
`
`
`
`
`
`Second, as discussed in Section VI below, de Sarte also does not disclose,
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`either expressly or inherently, “a control circuit coupled to generate a control
`
`signal in response to an output of the comparator and in response to an output of
`
`the feedback circuit, the control signal to be coupled to a control terminal of the
`
`switch to control switching of the switch,” as required by sole independent claim 1.
`
`This claim element requires that the control circuit be coupled to generate a control
`
`signal in response to two things: (1) the output the comparator, which is “a
`
`comparator . . . having a second input coupled to receive a variable current limit
`
`threshold that increases during the on time of the switch” and (2) “a feedback
`
`circuit coupled to receive a feedback signal representative of an output voltage at
`
`an output of a power supply.” At no time is the control circuit disclosed in de
`
`Sarte coupled to generate a control signal in response to both of these inputs even
`
`under Petitioner’s unreasonably broad reading of the current limit limitation. That
`
`is, the only time that the control circuit is coupled to respond to the feedback
`
`signal, the regulator is not in the startup mode, and the startup current limit
`
`oscillator (that allegedly provides the variable current limit threshold) is disabled
`
`such that there is only a fixed current limit threshold.
`
`Accordingly, the Board must conclude that the information presented in the
`
`Petition and accompanying evidence does not establish a reasonable likelihood that
`
`
`
`3
`
`
`
`
`Petitioner will prevail in showing the unpatentability of claims 1, 2, 5, and 9 of the
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`‘605 patent.
`
`II.
`
`PETITIONER IS TIME BARRED FROM SEEKING INTER PARTES
`REVIEW.
`Petitioner ON Semiconductor is time barred from seeking inter partes
`
`review under 35 U.S.C. § 315(b).
`
`Under 35 U.S.C. § 315(b), an inter partes review “may not be instituted if
`
`the petition requesting the proceeding is filed more than 1 year after the date on
`
`which the petitioner, real party in interest, or privy of the petitioner is served with a
`
`complaint alleging infringement of the patent.” “The notion of ‘privity’ is more
`
`expansive [than real party in interest].” Office Patent Trial Practice Guide, 77 Fed.
`
`Reg. 48,756, 48,759 (Aug. 14, 2012). Whether a party is a privy “is a highly fact-
`
`dependent question” and includes “relationships and considerations sufficient to
`
`justify applying conventional principles of estoppel and preclusion.” Id.
`
`Relevant factors include: Party A’s relationship with the petitioner; Party
`
`A’s relationship to the petition itself, including the nature and/or degree of
`
`involvement in the filing; and the nature of the entity filing the petition. In short,
`
`because rarely will one fact, standing alone, be determinative of the inquiry, the
`
`Office cannot prejudge the impact of a particular fact on whether a party is a ‘‘real
`
`party-in-interest’’ or ‘‘privy’’ of the petitioner. Id., 48,760. For example, a
`
`
`
`4
`
`
`
`
`Petitioner who has merged with a privy is time-barred under § 315(b) even if the
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`merger occurred after the privy was served with the complaint. See VMware, Inc.
`
`v. Good Technology Software, Inc., Case IPR2015-00027, slip op. at 4 (PTAB
`
`March 6, 2015) (Paper 11) (“Because [the] privy of Petitioner, was served with the
`
`Complaint alleging infringement [] more than a year before the Petition
`
`challenging the ’386 patent was filed, we are persuaded, on this record, that the
`
`Petition is not timely under § 315(b).”); see also Nestle USA, Inc. v. Steuben
`
`Foods, Inc., Case IPR2015-00195, slip op. at 10 (PTAB June 29, 2015) (agreeing
`
`with VMware that when an acquisition puts two parties in privity, it is appropriate
`
`to attribute the privy’s circumstances to the petitioner even if the petitioner was not
`
`a party to the complaint).
`
`On November 18, 2015, Petitioner entered into the Merger Agreement with
`
`Fairchild. See Ex. 2001 (copy of Agreement and Plan of Merger as filed with the
`
`SEC); Ex. 2002 (press release). Although ON Semiconductor argued in its petition
`
`that “it is uncertain when or whether the merger will close” (Petition at 1-2), the
`
`merger was completed the following month on September 20, 2016. See Ex. 2005
`
`(article about completion of merger between ON Semiconductor and Fairchild).
`
`Although Petitioner asserts that it and Fairchild “became real parties in interest as
`
`of the close of the merger on September 19, 2016” (Paper 6 at 3), in fact they were
`
`acting in privity well before receiving regulatory approval—and before the IPR
`
`
`
`5
`
`
`
`
`petition was filed—by coordinating efforts for future dealings pursuant to the
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`Confidentiality Agreement. The regulatory approval was a mere formality that
`
`may have further cemented a privity relationship that already existed, but it did not
`
`cause the relationship to arise in the first instance. Following payment, Fairchild
`
`ceased to be a publicly traded company and became a wholly owned subsidiary of
`
`ON Semiconductor. Id. Since Petitioner now owns Fairchild, Petitioner is
`
`successor-in-interest to the products that were found to infringe the ’605 patent.
`
`See Ex. 2006 (Dkt. No. 731 at 13) (“With respect to direct infringement, the Court
`
`will grant Power's motion for judgment as a matter of law. Fairchild admitted that
`
`it did ‘not present[] evidence of a defense with regard to direct infringement.’ In
`
`the absence of such evidence, no reasonable jury could have returned a verdict on
`
`this issue in Fairchild's favor.” (internal citation omitted)). As a result, the two
`
`parties are in privity regarding the interests and liabilities attached to products that
`
`infringe the ’605 patent. See Int’l Nutrition Co. v. Horphag Research, Ltd., 220
`
`F.3d 1325, 1329 (Fed. Cir. 2000) (“One situation in which parties have frequently
`
`been held to be in privity is when they hold successive interests in the same
`
`property.”); see also Pall Corp. v. Fisher Scientific Co., 962 F. Supp. 210 (D.
`
`Mass. 1997) (holding collateral estoppel applied to acquiring company regarding
`
`the issue of invalidity because acquirer was still selling acquired company’s
`
`infringing products). Fairchild is barred under 35 U.S.C. § 315(b) because it was
`
`
`
`6
`
`
`
`
`served with a complaint for infringement of the ’605 patent on June 6, 2011, in
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`Power Integrations, Inc., v. Fairchild Semiconductor International, Inc. et al.,
`
`Case No. 08-309-LPS (D. Del.) (“District Court Action”). See Ex. 2003 (Dkt. No.
`
`401). Because Fairchild is a privy to Petitioner, this inter partes review should be
`
`time-barred. See Aruze Gaming Macau, Ltd. v. MGT Gaming, Inc., Case IPR2014-
`
`01288, 2015 WL 780607, at *5 (PTAB Feb. 20, 2015) (“‘[A] party bound by a
`
`judgment may not avoid its preclusive force by relitigating through a proxy,’ such
`
`as ‘when a nonparty later brings suit as an agent for a party who is bound by a
`
`judgment.’” (quoting Taylor v. Sturgell, 553 U.S. 880, 892-93 (2008))).
`
`Otherwise, the Patent Office risks an end-run around section 315(b) in
`
`contradiction to Congressional intent. See H.R. Rep. No. 112-98, pt. 1, at 48
`
`(2011) (“The Committee recognizes the importance of quiet title to Patent Owners
`
`to ensure continued investment resources. . . . [AIA post grant challenges] are not
`
`to be used as tools for harassment or a means to prevent market entry through
`
`repeated litigation and administrative attacks on the validity of a patent.”).
`
`When Petitioner’s Merger Agreement with Fairchild became public on
`
`November 18, 2015, Fairchild had already been found to infringe the ’605 patent.
`
`Likewise, Fairchild’s invalidity defenses, including some based on nearly identical
`
`prior art as is cited in the Petition, had been rejected in District Court Action. See
`
`Petition at 25-27. Prior to the time of the Merger Agreement, and well before the
`
`
`
`7
`
`
`
`
`Petition was filed in this case, Petitioner and Fairchild also entered a
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`Confidentiality Agreement that addressed the parties’ ongoing legal proceedings,
`
`acknowledging that they “share a common legal and commercial interest” and “are
`
`or may become joint defendants in proceedings.” See Ex. 2007 (Confidentiality
`
`Agreement, dated September 14, 2015), page 7, section 16.
`
`Petitioner’s interest in the ’605 patent plainly stems directly from the District
`
`Court Action where Fairchild was found to infringe. Petitioner is a privy of
`
`Fairchild, despite the fact that the merger was not finalized until just after the filing
`
`of the Petition. Petitioner has even admitted to the Office that Fairchild is now one
`
`of the “real parties in interest” along with Petitioner. See Paper 6 at 3. Because
`
`under Section 315(b) a privy of a barred party is also barred, Petitioner ON
`
`Semiconductor is barred. See Aruze Gaming Macau, Ltd. v. MGT Gaming, Inc.,
`
`Case IPR2014-01288, 2015 WL 780607, at *5 (PTAB Feb. 20, 2015) (“‘[A] party
`
`bound by a judgment may not avoid its preclusive force by relitigating through a
`
`proxy,’ such as ‘when a nonparty later brings suit as an agent for a party who is
`
`bound by a judgment.’” (quoting Taylor v. Sturgell, 553 U.S. 880, 892-93 (2008))).
`
`This case is distinguishable from Synopsys, Inc. v. Mentor Graphics Corp.
`
`In that case, the Petition was filed before the Petitioner and its privy entered into
`
`their acquisition agreement. IPR2012-00042, Paper No. 16, at 16. And subsequent
`
`to the Synopsys decision, the Board has clarified that the date of service of the
`
`
`
`8
`
`
`
`
`complaint in litigation is not the sole focus for evaluating privity; after-arising
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`events are also relevant to the time-bar analysis under section 315(b). VMWare,
`
`Inc. v. Good Technology Software, Inc., IPR2015-00027, Paper No. 11, at 3-4
`
`(finding Petition barred and distinguishing Synopsys, noting that “we do not
`
`conclude that privity under § 315(b) is determined only at the time of service of a
`
`complaint alleging infringement of the challenged patent.”).
`
`Petitioner bears the burden of proving that it is not barred from seeking inter
`
`partes review. See 37 C.F.R. § 42.104(a). But Petitioner gives only a conclusory
`
`summary alleging that there is no privity because the merger had not yet closed
`
`and that Fairchild is not controlling the Petition—but the merger closed soon after
`
`the filing of the Petition and Fairchild is now a wholly owned subsidiary of
`
`Petitioner. Ex. 2005 (article about completion of the merger between ON
`
`Semiconductor and Fairchild). Petitioner did not address the relevant facts
`
`described above. Petitioner does not deny its relationship with Fairchild, that
`
`Petitioner, Fairchild, and the merged entity share the exact same goal of annulling
`
`the judgment against Fairchild. As the Trial Practice Guide states:
`
`The Office intends to evaluate what parties constitute
`
`“privies” in a manner consistent with the flexible and
`
`equitable considerations established under federal
`
`caselaw. Ultimately, that analysis seeks to determine
`
`
`
`9
`
`
`
`
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`whether the relationship between the purported “privy”
`
`and the relevant other party is sufficiently close such that
`
`both should be bound by the trial outcome and related
`
`estoppels.
`
`Office Patent Trial Practice Guide, 77 Fed. Reg. at 48,759. In this case, equity
`
`requires that Petitioner and Fairchild both be bound by the time bar circumstances
`
`related to Fairchild, and that those entities, acting in concert not be allowed to get a
`
`second bite at the apple. A contrary conclusion would create an opportunity for
`
`abuse of the inter partes review system. Under Petitioner’s arguments and
`
`circumstances, any company could circumvent the one year time limit of 35 U.S.C.
`
`§ 315(b) simply by merging with a second company and having the second
`
`company file the inter partes review petition. Surely § 315(b) was not enacted
`
`with such a result in mind. See H.R. Rep. No. 112-98, pt. 1, at 48 (2011) (“The
`
`Committee recognizes the importance of quiet title to Patent Owners to ensure
`
`continued investment resources. . . . [T]he changes made by it are not to be used as
`
`tools for harassment or a means to prevent market entry through repeated litigation
`
`and administrative attacks on the validity of a patent.”).1
`
`1 To the extent the Board is not inclined to find the petition time-barred at this
`
`stage, Patent Owner plans to request limited additional discovery into the terms of
`
`the Merger Agreement and communications between Fairchild and ON
`
`
`
`10
`
`
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`III. THE ‘605 PATENTED INVENTION AND TECHNICAL
`
`BACKGROUND
`
`A. Technology Background: “Switch-mode” power supplies and the
`
`cycle-by-cycle current limit
`
`
`
`It is well known in the art that all electronic devices (i.e., electronic “loads”)
`
`use electrical power to operate and thus typically require the use of a power supply
`
`to provide regulated electrical power. The ‘605 patent relates to “off-line” switch-
`
`mode power supplies, also known as switching power supplies, such as would be
`
`typically used for charging a cell phone or a laptop computer.
`
`Switching power supplies are used to achieve proper interfacing between a
`
`power source, such as an A/C source or battery, and a load, such as a portable
`
`computer. If the source is at a voltage that is too high or too low for the load, a
`
`switching power supply can be used to draw power from the source and provide it
`
`to the load at the proper voltage. This transfer of power is controlled by
`
`
`Semiconductor regarding the ’605 patent and the parties’ legal proceedings. Patent
`
`Owner believes such discovery would conclusively establish that the petition is
`
`barred under § 315(b) in view of the shared interests of Fairchild and ON
`
`Semiconductor with respect to the ’605 patent and the instant petition.
`
`
`
`
`
`11
`
`
`
`
`controlling the turning on and off of an electrical switch (typically a transistor) to
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`provide a steady output voltage or output current. A graph depicting a constant-
`
`current and constant-voltage regulator output is shown below and is found at FIG.
`
`5 of the ‘605 patent.
`
`
`
`In the manner shown above, the switching power supplies as disclosed in the
`
`‘605 patent are intended to regulate the power delivered to their output. This
`
`regulation may be of the output voltage or the output current. Together regulating
`
`both of these values achieves output power regulation (where output power =
`
`output voltage x output current). The technical tutorial discussion below focuses
`
`
`
`12
`
`
`
`
`on the basic operation and typical components of a power supply that regulates the
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`output voltage and output current to a load. This is provided as background to the
`
`art as would be understood by a person of ordinary skill in the art reading the ‘605
`
`patent. Both the ‘605 patent and the de Sarte reference referred to herein include
`
`the same basic fundamental components of a power supply that are described
`
`briefly below.
`
`A capacitor is an electrical element that can store electrical charge.
`
`Electrical current (the flow of electrical charge) drawn by the load is provided by
`
`charge stored on the regulator output capacitor.
`
`
`
`The regulator output voltage depends on the level of charge stored in the
`
`output capacitor. As the load drains charge off the capacitor, the regulator output
`
`voltage will decrease. To maintain a steady regulator output voltage, the regulator
`
`must recharge the output capacitor as charge is drained off by the load. As shown
`
`
`
`13
`
`
`
`
`in the figure below, the current to recharge the output capacitor is provided by a
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`power source such as 110V wall socket.
`
`
`
`Since the voltage across the output capacitor depends on the amount of
`
`charge it stores, regulating that voltage requires that the charge put into the
`
`capacitor by the regulator match the amount of charge taken out of the capacitor by
`
`the load current. A switching voltage regulator recharges its output capacitor by
`
`providing pulses of recharge current. In the example shown below, for an average
`
`level of load current, the recharging current flows half the time. The average
`
`recharge current, over time, matches the level of the load current, and the regulator
`
`output voltage will remain steady.
`
`14
`
`
`
`
`
`
`
`
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`
`
`If the load current level changes, the average level of recharging current
`
`must also change to maintain a steady level of charge in the capacitor. This can be
`
`achieved by modulating the pulse width (“on-time”) of each recharge pulse. For
`
`example, if the load current level increases (e.g., if the load is a laptop and its
`
`screen brightness is turned up), then the recharge pulse width will be increased by
`
`the regulator to provide the necessary discharge/recharge match. If the load
`
`current level decreases (e.g., if the load is a laptop and its screen brightness is
`
`turned down), then the recharge pulse width will be decreased by the regulator to
`
`provide the necessary discharge/recharge match. The figure below shows recharge
`
`pulse timing for three different levels of load current.
`
`
`
`15
`
`
`
`
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`
`
`Note that the recharge pulse frequency remains fixed, but the amount of time
`
`that the recharge current is flowing during each pulse cycle varies. This is known
`
`as pulse width modulation (“PWM”). Switching voltage regulators can use a
`
`transformer and a switch to provide the recharging current pulses.
`
`
`
`
`
`16
`
`
`
`
`
`A transformer is an energy transfer device and is formed by having two or
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`more coils of wire wound around the same core. As seen in the figure below, in a
`
`switching regulator, an input voltage source can be connected to one end of one of
`
`the transformer windings (the primary winding), and the switch can be connected
`
`to the other end of that winding.
`
`
`
`When the switch is turned on, current starts to flow through both the primary
`
`winding and the switch, and builds up (increases in value over time) as long as the
`
`switch is ON. This also increases the magnetic field in the transformer.
`
`When the switch turns off, current in the primary winding stops flowing, and
`
`the collapsing magnetic field induces current flow in the other (secondary)
`
`windings. Secondary current can be steered to the output capacitor to recharge it.
`
`
`
`17
`
`
`
`
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`
`
`The amount of energy transfer depends on the level of current previously
`
`built up in the primary winding, and thus the percentage of time that the switch
`
`was on during each on/off switching cycle. For a given level of load current, if the
`
`duty cycle is too high, there is more recharging from energy transfer than there is
`
`discharging by load current. This causes the regulator output voltage to increase.
`
`If duty cycle is too low, there is less recharging from energy transfer than
`
`discharging by load current, and the regulator output voltage will decrease.
`
`Regulators typically use feedback to maintain a steady output voltage. As
`
`shown below, the regulator monitors output voltage and uses a signal from the
`
`output to adjust the switch timing (e.g., the pulse width) to be just right.
`
`
`
`18
`
`
`
`
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`
`
`Switching regulators often use an oscillator to provide system timing. The
`
`oscillator puts out a periodic series of pulses to turn on the switch at the beginning
`
`of each switch cycle. In pulse width modulation, the switch duty cycle is
`
`controlled by determining when to turn the switch off during each switching cycle.
`
`Integrated circuit power supply controller chips often provide other
`
`functions in addition to the basic regulation function. In the case of the ‘605
`
`patent, the additional function at issue is a current limit, which prevents excessive
`
`and perhaps destructive current flow in a power switch on a cycle-by-cycle basis.
`
`In particular, by regulating the maximum current output by the regulator and the
`
`maximum voltage output by the regulator, a person of skill in the art can control
`
`
`
`19
`
`
`
`
`the maximum power output by the regulator. The maximum power output by the
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`regulator must be accurately known in order to ensure that the components of the
`
`power supply are sufficient to handle all operating modes of the power supply.
`
`The Invention of the ‘605 Patent
`
`B.
`
`As explained above, and as expressly stated in the ‘605 patent, one
`
`exemplary form of power supply that is efficient and, at the same time, provides
`
`acceptable output regulation to supply power to electronic devices is the “switch-
`
`mode” power supply. Ex. 1001 at 1:28-32. In many electronics, especially low
`
`power electronics that use wall outlet supplied power – i.e., “off line” power –
`
`during the normal operating load range of the power supply, an approximately
`
`constant output voltage is required when the load current is below an output
`
`current threshold (e.g., when the load current is not at the maximum). Id. at 1:32-
`
`36. In addition to regulating the output voltage, the output current is generally
`
`regulated to be approximately constant at or above that threshold, at which point,
`
`the output voltage may drop its regulated voltage – in this context, this is referred
`
`to as the output voltage threshold. Id. at 1:36-38.
`
`For several reasons, it is desirable to limit the maximum output current of a
`
`power supply because by controlling the maximum voltage and the maximum
`
`current (which occurs at the output voltage threshold), you control the maximum
`
`
`
`20
`
`
`
`
`output power of the power supply. A load device, operating at its regulated
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`voltage, might draw more current from the power supply because it is performing
`
`more functions at once. For example, a laptop computer that is playing music and
`
`maintaining an internet connection would draw more current than one sitting idle.
`
`A power supply should be designed to accommodate whatever current the intended
`
`load device requires. But if the device attempts to draw too much current, perhaps
`
`due to a fault condition, the power supply should also be capable of preventing
`
`damage due to overload. Dangerous conditions, such as overheating, may develop
`
`if a load is able to draw too much current.
`
`The ’605 patent relates to current limit circuits used in switching power
`
`supplies. The patent describes a switched mode power supply in which the output
`
`current below the output voltage threshold, is regulated to be approximately
`
`constant. Ex. 1001 at 3:1-3. As is explained, in known, prior art, power supplies
`
`the output current level at the output voltage threshold is typically sensed at the
`
`output of the power supply to provide feedback to a regulator circuit coupled to the
`
`primary winding of the power supply. Id. at 3:5-13. But, if the approximately
`
`constant current functionality is achieved without feedback from the secondary
`
`winding side of the power supply, the output current at the output voltage threshold
`
`is a function of a peak current limit of the power supply (i.e., the current limit of
`
`
`
`21
`
`
`
`
`the power supply’s power switch). Id. The patent describes how this peak current
`
`Case IPR2016-01600
`Attorney Docket No: 10256-0021IPC
`
`limit is controlled to thereby control the maximum output current.
`
`In particular, the patent discloses a current limit circuit and method that
`
`enable the power supply to maintain an approximately constant output current
`
`below the output voltage threshold over varying input voltage (i.e., over variations
`
`in supplied input voltage at one location or variations in input voltage levels
`
`around the world.). Ex. 1001 at 1:50-2:18. Broadly speaking, the disclosed
`
`invention achieves this by increasing the current limit threshold during the
Accessing this document will incur an additional charge of $.
After purchase, you can access this document again without charge.
Accept $ Charge
Still Working On It
This document is taking longer than usual to download. This can happen if we need to contact the court directly to obtain the document and their servers are running slowly.
Give it another minute or two to complete, and then try the refresh button.
A few More Minutes ... Still Working
It can take up to 5 minutes for us to download a document if the court servers are running slowly.
Thank you for your continued patience.
This document could not be displayed.
We could not find this document within its docket. Please go back to the docket page and check the link. If that does not work, go back to the docket and refresh it to pull the newest information.
Your account does not support viewing this document.
You need a Paid Account to view this document. Click here to change your account type.
Your account does not support viewing this document.
Set your membership
status to view this document.
With a Docket Alarm membership, you'll
get a whole lot more, including:
- Up-to-date information for this case.
- Email alerts whenever there is an update.
- Full text search for other cases.
- Get email alerts whenever a new case matches your search.
One Moment Please
The filing “” is large (MB) and is being downloaded.
Please refresh this page in a few minutes to see if the filing has been downloaded. The filing will also be emailed to you when the download completes.
Your document is on its way!
If you do not receive the document in five minutes, contact support at support@docketalarm.com.
Sealed Document
We are unable to display this document, it may be under a court ordered seal.
If you have proper credentials to access the file, you may proceed directly to the court's system using your government issued username and password.
Access Government Site
