PTAB

IPR2016-01600

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: Power Supply Regulator with Variable Current Limit Threshold
  • Brief Description: The ’605 patent relates to switch mode power supply circuits. The disclosed technology aims to solve the problem of undesirable variations in the output current, which can be caused by differing input voltages, by employing a control circuit with a variable current limit threshold that increases during the "on-time" of the power switch.

3. Grounds for Unpatentability

Ground 1: Anticipation by de Sartre - Claims 1, 2, 5, and 9 are anticipated by de Sartre under 35 U.S.C. § 102.

  • Prior Art Relied Upon: de Sartre (Patent 4,692,853).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that de Sartre, which discloses a "chopped power supply control circuit," explicitly or inherently teaches every limitation of the challenged claims. For independent claim 1, Petitioner mapped the elements as follows:
      • "A power supply regulator": Petitioner asserted this is met by de Sartre’s overall control circuit, including regulation circuits CI1 and CI2, which regulate the power supply output.
      • "a comparator having a first input coupled to sense a voltage representative of a current...through a switch" and a second input for a "variable current limit threshold that increases during the on time of the switch": Petitioner identified comparator 92 in de Sartre as the claimed comparator. Its first input (terminal 44) senses current through the power switch (transistor Tp). Its second input receives a threshold signal from circuit 90, which, during a "safety mode," provides a progressively increasing current limit threshold to protect the transistor during startup. Petitioner contended this threshold increases during the on-time of the switch within each enablement window.
      • "a feedback circuit": Petitioner mapped this to de Sartre's regulation circuit CI2, which examines the output voltage Vs and transmits corresponding regulation signals back to the primary side.
      • "a control circuit": Petitioner identified the combination of OR gate 60, flip flop 50, and other logic in de Sartre's circuit CI1 as the claimed control circuit. This circuit receives inputs from the comparator (92) and the feedback circuit (CI2) to generate a control signal that turns the switch (Tp) on and off.
    • Dependent Claims Mapping: Petitioner argued de Sartre also anticipates the dependent claims. Claim 2’s requirement for an oscillator generating a sawtooth waveform was mapped to oscillator 82 in de Sartre, which drives the variable threshold circuit. Claim 5’s requirement for a latch in the control circuit was mapped to flip flop 50. Claim 9’s requirement that the control signal’s duty cycle is modulated by the feedback circuit was mapped to de Sartre’s disclosure of generating "square waves having a variable width" based on the regulation signals received from the feedback circuit.
    • Key Aspects: Petitioner's core argument rested on the assertion that the patent owner broadened the claims of the ’605 patent during prosecution compared to its parent application. Specifically, the limitation requiring the regulator to produce an "approximately constant output current" was removed. Petitioner contended that this broadening made the claims susceptible to anticipation by prior art like de Sartre, which uses a variable current limit for a different purpose (transistor protection) but whose structure nevertheless meets every element of the broadened claims.

4. Key Technical Contentions (Beyond Claim Construction)

  • Petitioner argued that the claim phrase "increases during the on time of the switch" does not require any specific magnitude or rate of increase. Any increase, regardless of how small, during the switch's on-time satisfies the claim limitation. Petitioner highlighted that in a previous litigation involving a similar patent (Maige), the Patent Owner had argued that a very slight increase was insufficient to meet the limitation. Petitioner contended this position is incorrect and that de Sartre’s progressively increasing threshold during enablement windows, where the switch is active, squarely meets this limitation as written in the challenged claims.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1, 2, 5, and 9 of Patent 7,834,605 as unpatentable.