PTAB

IPR2016-00809

Semiconductor Components Industries LLC doing Business As On Semiconductor v. Power Integrations Inc

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Switch Mode Power Supply Circuits
  • Brief Description: The ’079 patent discloses switch mode power supply circuits designed to improve efficiency under light load conditions. The invention purports to overcome the disadvantages of prior art "cycle skipping" techniques by instead extending the switching period (i.e., lowering the switching frequency) of each individual switching cycle in response to a light load, thereby reducing switching losses without introducing audible noise or degrading output ripple.

3. Grounds for Unpatentability

Ground 1: Obviousness over Oda and Nakamura - Claims 31, 32, 34, 38, 39, and 42 are obvious over Oda in view of Nakamura.

  • Prior Art Relied Upon: Oda (Japanese Application # H10-323028) and Nakamura (Japanese Application # S59-144366).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Oda disclosed the core inventive concept: a switching regulator that operates in two modes based on load conditions detected via a feedback signal. For heavier loads, it operates at a fixed switching frequency, and for lighter loads, it reduces the switching frequency by increasing the switching period, without skipping cycles, to improve efficiency. This functionality maps directly to the limitations in independent claims 31, 34, 38, and 42 regarding a control circuit that switches at a fixed frequency for a first range of feedback values and a variable frequency for a second range. Petitioner contended that the only significant element of the claims not explicitly found in Oda is the use of a transformer as the "energy transfer element," as Oda discloses a buck-type power stage using an inductor. Nakamura was argued to cure this by teaching a switching regulator with similar dual-mode (pulse-width and frequency) control that explicitly discloses its suitability for use in various power supply topologies, including both a buck-type power stage (like Oda) and a flyback-type power stage that uses a transformer.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the teachings of Oda and Nakamura as a simple substitution of one known element for another to obtain a predictable result. Petitioner asserted that a POSITA would be motivated to replace the buck-type power stage in Oda with the flyback-type power stage taught by Nakamura to gain the well-known advantages of using a transformer, such as DC isolation between the input and output and better optimization for large voltage conversion ratios.
    • Expectation of Success: Given that Nakamura explicitly taught the interchangeability of power stages for its control circuit and the functions of both buck and flyback topologies were well-understood, a POSITA would have had a high expectation of success in implementing Oda’s control scheme with a flyback topology.

Ground 2: Anticipation by Oda - Claims 31, 32, 34, 38, 39, and 42 are anticipated by Oda.

  • Prior Art Relied Upon: Oda (Japanese Application # H10-323028).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground was presented as an alternative to Ground 1 and is contingent upon the Board adopting Petitioner's proposed construction of the claim term "energy transfer element." Petitioner argued that this term should be construed to mean "an inductive element such as a transformer or an inductor." Under this construction, the "choke coil 4" (an inductor) in Oda's buck-type power stage would satisfy the "energy transfer element" limitation of the claims. As Oda already discloses all other key limitations, including the dual-mode (fixed and variable frequency) operation based on load conditions without skipping cycles, Petitioner argued that Oda alone anticipates each of the challenged claims. This ground does not rely on any combination of references.

4. Key Claim Construction Positions

  • "energy transfer element": Petitioner proposed this term be construed as "an inductive element such as a transformer or an inductor."
    • Rationale: The petition argued that this construction is consistent with the term's plain meaning in the art at the time of the invention. It cited prior art patents, including one from the Patent Owner, that explicitly referred to both transformers (in flyback topologies) and inductors (in buck-type topologies) as "energy transfer elements." As the challenged claims recite a "switching regulator" without being limited to a specific power supply topology (e.g., flyback), Petitioner contended the term should not be narrowly limited to only a transformer. This construction is critical to Ground 2, where Oda's inductor is alleged to satisfy this claim element, thereby making Oda an anticipatory reference.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 31, 32, 34, 38, 39, and 42 of the ’079 patent as unpatentable under 35 U.S.C. §§ 102 and 103.