PTAB

IPR2018-01810

Semiconductor Components Industries, LLC d/b/a ON Semiconductor v. Power Integrations, Inc.

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1. Case Identification

2. Patent Overview

  • Title: Controller for a Power Converter with Input and Output Voltage Sensing
  • Brief Description: The ’871 patent discloses a controller for a switching power converter, specifically a flyback-type converter. The controller uses a single terminal coupled to an auxiliary transformer winding to sense both the input line voltage (during the power switch's on-time) and the output voltage (during the power switch's off-time) for purposes of regulation and fault protection.

3. Grounds for Unpatentability

Ground 1: Anticipation over Mobers - Claims 1-3, 6, 8, 12, 14, and 15 are anticipated 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 the challenged claims. Mobers teaches a flyback-type switching power converter with an integrated circuit (IC) controller that uses a "control winding" (an auxiliary winding) to monitor both input and output voltages. Petitioner asserted that Mobers' controller receives a signal from this auxiliary winding via a single input pin, satisfying a key limitation. Mobers explicitly stated that "information relating to Vline will be present on the control winding ... during the primary stroke [on-time], whereas information relating to the output voltage Vout will be present during the secondary stroke [off-time]." Furthermore, Petitioner mapped Mobers' PWM control circuitry to the ’871 patent's "switching control" and Mobers' "over power protection system," which limits power based on sensed input voltage, to the claimed "power limiter." The over-voltage protection circuit in Mobers was mapped to the "output fault detector" of claims 3 and 8.

Ground 2: Obviousness of Claim 11 over Mobers - Claim 11 is obvious under 35 U.S.C. §103.

  • Prior Art Relied Upon: Mobers (Patent 6,542,386).

  • Core Argument for this Ground:

    • Prior Art Mapping: Claim 11, which depends from claim 8, adds the limitation that the "output fault detector is coupled to detect an open loop condition fault condition." Petitioner asserted that the ’871 patent does not define this term. Based on expert testimony, an "open loop condition" is understood by a person of ordinary skill in the art (POSITA) as a break in the feedback path from the power supply output to the control circuitry. This break causes the controller to falsely detect low or no output voltage, leading it to deliver maximum power and, predictably, cause an output over-voltage fault. Petitioner argued that Mobers' over-voltage protection circuit (the output fault detector from claim 3) is therefore inherently capable of detecting an open loop condition by detecting its direct symptom—the resulting over-voltage.
    • Motivation to Combine: A POSITA would have been motivated to use Mobers' existing over-voltage detector to address an open loop condition because an over-voltage fault is a well-known and direct consequence of a broken feedback loop. The background of Mobers itself acknowledged that a broken loop results in an over-voltage condition for which protection is needed. Therefore, detecting the symptom (over-voltage) is a direct and logical way to detect the underlying cause (open loop condition).
    • Expectation of Success: A POSITA would have had a high expectation of success. The task did not involve modification, but rather the recognition that Mobers' disclosed over-voltage protection circuit would inherently and predictably respond to the over-voltage caused by an open loop fault, thus detecting the condition as recited in claim 11.

  • Additional Grounds: Petitioner asserted as a fallback position that claims 1-3, 6, 8, 12, 14, and 15 are also obvious over Mobers under §103. This argument relied on the same mappings as the anticipation ground and contended that, even accounting for a potential typographical error in Mobers, a POSITA would have readily understood the disclosure or found it obvious to sense both input and output voltages from the single auxiliary winding terminal.

4. Key Claim Construction Positions

  • Petitioner maintained that all claim terms should be given their plain and ordinary meaning. However, it specifically addressed the "switching control" limitations in claims 1 and 14.
  • Petitioner argued that the phrases "a switching control to be coupled" and "wherein the switching control is further coupled" do not require separate or additional physical couplings between the sensor, switching control, and power switch.
  • To support this, Petitioner cited the Patent Owner's own infringement contentions from related district court litigation, where the Patent Owner allegedly mapped the same circuit components of an accused product to both the "coupled to" and "further coupled to" limitations, implying a single set of connections satisfies both claim elements.

5. Relief Requested

  • Petitioner requests institution of an inter partes review of the ’871 patent and cancellation of claims 1-3, 6, 8, 11, 12, 14, and 15 as unpatentable.