PTAB

IPR2018-01816

Semiconductor Components Industries LLC v. Power Integrations Inc

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1. Case Identification

2. Patent Overview

  • Title: Controller for Power Converter
  • Brief Description: The ’483 patent discloses a controller for a switching power converter, such as a flyback converter. The controller uses a single terminal to receive a signal from an auxiliary winding of a transformer, where the signal is representative of the converter’s output voltage when the power switch is off and representative of the input line voltage when the power switch is on.

3. Grounds for Unpatentability

Ground 1: Claims 1 and 7 are anticipated by Mobers under 35 U.S.C. §102.

  • Prior Art Relied Upon: Mobers (Patent 6,542,386).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Mobers discloses every element of claims 1 and 7. Specifically, Mobers teaches a controller for a switched-mode power supply that uses a "control winding" (auxiliary winding). A sensor in the controller is coupled to receive a signal from this winding via a single input pin. This signal represents the input line voltage (Vline) during the switch’s on-time (“primary stroke”) and the output voltage (Vout) during the switch’s off-time (“secondary stroke”). The switching control is responsive to the sensor for both over-power protection (based on Vline) and over-voltage protection (based on Vout). Petitioner asserted that Mobers' controller is implemented in an integrated circuit (IC), thus anticipating claim 7 as well.

Ground 2: Claims 1 and 7 are obvious over Mobers under 35 U.S.C. §103.

  • Prior Art Relied Upon: Mobers (Patent 6,542,386).
  • Core Argument for this Ground:
    • Prior Art Mapping: As an alternative to anticipation, Petitioner argued that claims 1 and 7 are obvious over Mobers. This ground addresses a potential typographical error in Mobers that refers to Vline twice when describing the signal during both the primary and secondary strokes. Petitioner contended that a person of ordinary skill in the art (POSITA) would have immediately recognized this as an error and understood that the signal during the secondary stroke must relate to Vout, as is fundamental to flyback converter operation and as clarified elsewhere in Mobers.
    • Motivation to Combine (for §103 grounds): Not applicable, as this ground relies on a single reference and the general knowledge of a POSITA to correct a clear error.
    • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success in interpreting the disclosure correctly, as it aligns with the known physics of auxiliary windings and other explicit statements within Mobers.

Ground 3: Claims 1-3 and 7 are obvious over Reinhard under 35 U.S.C. §103.

  • Prior Art Relied Upon: Reinhard (Application # 2005/0254268).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Reinhard, in combination with the knowledge of a POSITA, renders the challenged claims obvious. Reinhard discloses a control circuit for a switched-mode power supply that receives a signal from an auxiliary winding at a single terminal ("U" terminal). A POSITA would understand that the inherent magnetic coupling in Reinhard's transformer causes the auxiliary winding to produce a positive voltage pulse representative of the output voltage during the switch off-time and a negative voltage pulse representative of the input line voltage during the switch on-time. Reinhard's sensor uses these signals for output voltage regulation and protection features, making the switching control responsive to the sensor.
    • Prior Art Mapping (Dependent Claims): For claim 2, Petitioner asserted Reinhard’s sensor (including sample and hold circuit 108) samples the signal during the off-time to detect the output voltage. For claim 3, Petitioner argued Reinhard discloses delaying this sampling for a period after the switch transitions off, as shown in its timing diagrams where sampling occurs at approximately two-thirds of the duration of the positive voltage pulse. Finally, Reinhard teaches that its controller can be implemented as an application-specific integrated circuit (ASIC), meeting the limitation of claim 7.
    • Motivation to Combine (for §103 grounds): A POSITA would be motivated to use the known properties of an auxiliary winding signal, as disclosed by Reinhard, to implement control and protection functions in a power converter to improve performance and reliability.
    • Expectation of Success (for §103 grounds): Success would be expected, as Reinhard explicitly describes using both the positive and negative voltage pulses from the auxiliary winding for control and protection, utilizing standard circuit components.

4. Key Claim Construction Positions

  • "switching control": Petitioner argued that this term requires no special construction beyond its plain meaning. Petitioner noted that the Patent Owner, in related litigation, applied a broad view of this term, and the prior art circuits (like the current mode architecture in Mobers) fall within that broad scope.
  • "to represent": Petitioner contended that the claim phrase "the signal... to represent a line input voltage... [and] an output voltage" defines the inherent characteristics of the signal itself. It does not, Petitioner argued, impose a requirement on how the separately recited "sensor" must act upon or process both pieces of information. This construction was central to distinguishing prosecution history arguments where the Patent Owner focused on what the signal represents, not how the controller responds to it.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-3 and 7 of the ’483 patent as unpatentable.