PTAB

IPR2018-01815

Semiconductor Components Industries LLC v. Power Integrations Inc

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1. Case Identification

2. Patent Overview

  • Title: Method for Protecting a Power Supply from Fault Conditions
  • Brief Description: The ’788 patent discloses a fault protection method for "on/off" controlled switching power supplies. The technology involves a control circuit that monitors a feedback signal to detect a fault condition, disables a switching device for a first period upon fault detection, and automatically enables the switching device after a second period to attempt a restart.

3. Grounds for Unpatentability

Ground 1: Obviousness over Barbehenn, King, and Grebene - Claims 14-17, 22, and 23 are obvious over Barbehenn in view of King and Grebene.

  • Prior Art Relied Upon: Barbehenn (Patent 5,914,865), King (Patent 5,694,305), and Grebene (a 1984 textbook titled "Bipolar and MOS Analog Integrated Circuit Design").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Barbehenn taught a switching converter with a "bang-bang" architecture, including a switching device (FET), a feedback loop using an optocoupler, and a 555 timer to generate a switching signal. However, Barbehenn was said to only address input fault protection. King was alleged to teach a dedicated, timer-based protection circuit for output faults, such as short circuits. Petitioner asserted that this circuit works by monitoring a feedback signal and, upon detecting a fault (e.g., the signal remaining high for a set period), disabling switching for a first period before attempting an auto-restart. The combination allegedly taught timing Barbehenn's feedback signal with King's timer circuit to detect a fault. Grebene was cited for background knowledge, showing the standard internal circuitry of a 555 timer and confirming the compatibility of the components in Barbehenn and King.
    • Motivation to Combine: A POSITA would combine King's well-known output fault protection circuit with Barbehenn's converter to improve its robustness against short circuits, a known problem in the art. This combination represented the application of a known technique to a known device to achieve predictable results. Grebene provided standard reference material that a POSITA would use to facilitate the integration.
    • Expectation of Success: A POSITA would have a high expectation of success because both Barbehenn and King operate in the same field of switching power converters and utilize common components like 555 timers. King's protection circuit was described as a flexible, modular solution intended for use with various converter types, making its integration with Barbehenn's circuit straightforward.

Ground 2: Obviousness over Krupka and Kent - Claims 14-17, 22, and 23 are obvious over Krupka in view of Kent.

  • Prior Art Relied Upon: Krupka (Patent 4,413,224) and Kent (Patent 4,447,841).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Krupka disclosed a DC/DC conversion system with an "on/off" control scheme where a digital feedback signal (either high or low) from a comparator enables or disables pulses to a switching device. While Krupka acknowledged overvoltage protection, it was argued to lack robust protection against short-circuit faults. Kent was alleged to disclose a dedicated protection circuit to solve this exact problem. Kent's circuit uses a timer (timing capacitor 263) to monitor a feedback signal. If the signal remains high for a predetermined period, indicating a fault, Kent's circuit generates a disable signal to shut down switching and initiates an auto-restart cycle. Petitioner argued for adding Kent's circuit to monitor Krupka's feedback signal and to provide a disable signal to an input of Krupka's AND-gate (3) to halt switching during a fault.
    • Motivation to Combine: A POSITA would have been motivated to improve the Krupka converter by incorporating Kent's known technique for short-circuit protection. This addresses a known deficiency in power supplies and would prevent component damage, such as from the "excessive heat buildup" described by Kent.
    • Expectation of Success: Success would be predictable because Kent’s protection circuit is designed to be separate from the feedback loop and operates based on a simple high/low level signal, which is precisely what Krupka's digital feedback signal provides. The combination would have been a straightforward integration of a known protection module into a standard converter design.

4. Key Claim Construction Positions

  • Petitioner argued that several key terms, which were part of a dispute in a related litigation, should be given their plain and ordinary meaning and that the Patent Owner’s proposed constructions were improperly narrow. Petitioner maintained its obviousness arguments held under either party's proposed constructions.
  • "feedback signal cycling": Petitioner asserted this term should encompass any signal, whether analog or digital, that cycles between two states during normal operation. This was in contrast to the Patent Owner's allegedly narrow construction that would improperly exclude certain types of signals.
  • "cycling separately": Petitioner contended this limitation simply requires that the switching signal and feedback signal are distinct and that the switching signal's cycling is not based on the feedback signal's cycling. This opposed the Patent Owner’s allegedly more complex and unsupported definition.

5. Relief Requested

  • Petitioner requests institution of an inter partes review for claims 14-17, 22, and 23 of the ’788 patent and cancellation of those claims as unpatentable under 35 U.S.C. §103.