PTAB

IPR2018-00380

Power Integrations Inc v. Semiconductor Components Industries LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method and Apparatus of Providing Synchronous Regulation for Offline Power Converter
  • Brief Description: The ’407 patent relates to a synchronous rectification and regulation circuit for an offline power converter. The invention purports to improve power conversion efficiency by integrating the synchronous rectifying circuit with the regulation circuit on the secondary side of a transformer, thereby generating control signals for both the primary and secondary sides without needing an additional, power-consuming switching stage.

3. Grounds for Unpatentability

Ground 1: Obviousness over Huang and IR2110 - Claims 1, 9, 15-18, 30, and 31 are obvious over Huang in view of IR2110.

  • Prior Art Relied Upon: Huang (Patent 7,193,866) and IR2110 (an International Rectifier datasheet, No. PD60147).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Huang discloses a half-bridge LLC resonant converter that meets nearly all limitations of the challenged claims. Huang’s secondary-side controller (70) adjusts its output frequency based on the converter's output voltage (Vo), thereby functioning as the claimed "secondary-side switching circuit." This controller generates differential "pulse signals" to directly drive its secondary-side synchronous rectifiers (50, 60) and a "synchronous signal" transferred via an isolation transformer (80) to the primary-side switches (10, 20). Petitioner asserted that the primary element not explicitly detailed in Huang, but functionally required, is the specific "control circuit" that would buffer the controller's output and drive the gates of the synchronous rectifier MOSFETs.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would have understood that Huang's controller (70) would provide logic-level signals, and a dedicated driver circuit would be necessary to effectively drive the power MOSFETs (50, 60). Petitioner asserted that a POSITA would be motivated to implement this required driver function using a standard, off-the-shelf high-side driver IC like IR2110. The IR2110 datasheet describes it as a high-speed power MOSFET driver, making it a natural and obvious choice for implementing the functionality described in Huang. This combination represented a simple substitution of a generic, inherent driver with a specific, known IC to yield a predictable and efficient result.
    • Expectation of Success: Integrating a standard driver IC into a known power converter topology was a routine task for a POSITA. Because IR2110 was designed for this exact purpose, a designer would have had a high expectation of success. The petition further argued that this combination renders obvious dependent claims reciting a latch circuit (claims 16, 30), as the functional block diagram of IR2110 explicitly shows an internal latch circuit that controls its output driver.

Ground 2: Obviousness over Huang, IR2110, and SC4910 - Claims 5 and 6 are obvious over Huang in view of IR2110 and SC4910.

  • Prior Art Relied Upon: Huang (Patent 7,193,866), IR2110 (International Rectifier datasheet No. PD60147), and SC4910 (a SEMTECH SC4910A/B datasheet).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon Ground 1 to challenge dependent claims 5 and 6, which add a "maximum-duty circuit" and a "current-sense device," respectively. Petitioner argued that while the base combination of Huang and IR2110 renders the limitations of claim 1 obvious, SC4910 provides an express teaching for the additional protective features recited in claims 5 and 6.
    • Motivation to Combine: Petitioner contended that implementing a maximum duty cycle limit and over-current protection are fundamental design principles for ensuring the safety and reliability of any switching power supply. A POSITA designing the Huang/IR2110 circuit would have been motivated to add these features to prevent "shoot-through" (simultaneous conduction of primary switches) and to protect the circuit from damaging over-current fault conditions. The SC4910 datasheet provides a concrete example of a secondary-side controller that implements these exact features. It explicitly teaches using external resistors to set a maximum duty cycle and using a dedicated current sense (CS) pin to disable switching signals during an over-current event. A POSITA would combine the teachings of SC4910 to incorporate these proven protection methodologies into the Huang/IR2110 circuit.
    • Expectation of Success: Adding standard protection circuits, as taught by SC4910, to a power converter was a well-understood practice in the field. A POSITA would have had a high expectation of success in integrating these known functions for their intended and known purposes of improving circuit robustness and reliability.

4. Relief Requested

  • Petitioner requested institution of an inter partes review (IPR) and cancellation of claims 1, 5-6, 9, 15-18, 30, and 31 of the ’407 patent as unpatentable under 35 U.S.C. §103 for each of the grounds presented.