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

1. Case Identification

• Case #: IPR2016-01590
• Patent #: 6,212,079
• Filed: August 11, 2016
• Petitioner(s): Semiconductor Components Industries, LLC d/b/a ON Semiconductor
• Patent Owner(s): Power Integrations, Inc.
• Challenged Claims: 1-7, 9, 17-19, 30, 33, 37, 40-41, 45-52

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 techniques like cycle skipping by instead increasing the switching period (i.e., lowering the frequency) of each switching cycle in response to a light load, thereby reducing switching losses.

3. Grounds for Unpatentability

Ground 1: Claims 1-7, 9, 17-19, 40, 45, 47, 49, 50, and 52 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 discloses a switching regulator with a control circuit that meets key claim limitations, including operating at a fixed frequency for a first range of feedback signals (corresponding to heavier loads) and varying the switching frequency for a second range (lighter loads) without skipping cycles. However, Oda's power stage is configured in a buck-type topology using an inductor. Nakamura was cited for its teaching that a switching regulator can be implemented with either a buck-type power stage (like Oda) or a flyback-type power stage using a transformer.
  • Motivation to Combine: A POSITA would combine these references by replacing the buck-type power stage in Oda's circuit with a flyback-type power stage as taught by Nakamura. Petitioner asserted the motivation was to achieve the well-known benefits of a transformer-based flyback topology, such as DC isolation between the input and output and better converter optimization for large voltage conversion ratios.
  • Expectation of Success: Petitioner contended that substituting one known power-stage topology for another was a simple substitution of one known element for another to obtain a predictable result, leading to a high expectation of success.

Ground 2: Claims 1-7, 9, 17-19, 40, 45, 47, 49, 50, and 52 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 on claim construction. Petitioner argued that if the term "energy transfer element" is construed to encompass inductors (as used in Oda's buck-type circuit), then Oda alone discloses every limitation of the challenged claims. Oda's circuit includes a control circuit that switches a power switch (FET 2) coupled to an inductor ("choke coil 4"), generates a feedback signal responsive to the output, and operates in both fixed-frequency and variable-frequency modes based on load conditions, all while the output is in regulation.
  • Key Aspects: This anticipation argument hinges entirely on the Board adopting Petitioner's proposed construction for "energy transfer element."

Ground 3: Claims 30, 33, 37, 41, 46, 48, and 51 are obvious over Oda, Nakamura, and Bucher.

• Prior Art Relied Upon: Oda (Japanese Application H10-323028), Nakamura (Japanese Application S59-144366), and Bucher (Patent 4,683,529).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground builds upon the combination of Oda and Nakamura from Ground 1. Petitioner argued that while Oda teaches reducing the switching frequency at light loads, it does not specify a minimum frequency. Bucher addresses the known problem of audible noise generated by switching regulators operating at low frequencies. Bucher explicitly teaches setting the minimum switching frequency of its regulator at 25 kHz to "ensure that the operation of the circuit remains above the audible range of human hearing."
  • Motivation to Combine: A POSITA, having combined Oda and Nakamura to create a variable-frequency regulator, would be further motivated to incorporate the teachings of Bucher. The motivation would be to solve the known and undesirable problem of audible noise at light loads by setting a minimum operational frequency, a predictable solution to a known problem.
  • Expectation of Success: Applying Bucher's technique of limiting the minimum switching frequency to the known regulator of Oda was presented as a straightforward design choice that would predictably result in a quieter power supply.
• Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground 4) against claims 30, 33, 37, 41, 46, 48, and 51 based on the combination of Oda and Bucher alone. This ground relied on the same logic as Ground 3 but was contingent on the Board construing "energy transfer element" to include an inductor, thereby obviating the need for Nakamura.

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." This construction is critical to its anticipation argument in Ground 2, as Oda's circuit uses an inductor. Petitioner argued this construction is supported by the patent's specification and the term's use in the art at the time.
• "Supply Rail": Petitioner argued this term should be construed as "a rail that supplies power, including, e.g., a positive or ground rail," consistent with a position Patent Owner allegedly took in prior litigation. This construction would mean that current could flow in either direction through the power switch, countering a potential argument for a more limited interpretation.

5. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-7, 9, 17-19, 30, 33, 37, 40-41, and 45-52 of the ’079 patent as unpatentable under 35 U.S.C. §102 and §103.