PTAB

IPR2018-01453

Apple Inc v. Qualcomm Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Switching Battery Charging Systems and Methods
  • Brief Description: The ’591 patent discloses circuits for charging a battery from a limited-power Universal Serial Bus (USB) source using a switching regulator. A core feature of the invention is maintaining an approximately constant input current by reducing the charging current into the battery as the battery's voltage increases while operating in a current control mode.

3. Grounds for Unpatentability

Ground 1: Claims 1-5, 7, 8, 10-13, 15-39, and 42-45 are obvious over Bryson in view of Sherman and bqSWITCHER.

  • Prior Art Relied Upon: Bryson (Patent 6,144,187), Sherman (Maxim Integrated Application Note 3241), and bqSWITCHER (Texas Instruments bq24100 Datasheet).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of these references teaches every limitation of the challenged claims. Bryson was presented as the primary reference, disclosing the core inventive concept: an "adaptive battery charger" with a switching regulator and multiple feedback loops, including a power control loop. Petitioner asserted this power loop "regulates charging current... to respect the maximum power limit," which inherently involves reducing the charging current as battery voltage rises to avoid exceeding the available input power. This, Petitioner contended, is precisely the "current control mode" that the patent examiner failed to appreciate in Bryson during prosecution.
    • Sherman was argued to supply the motivation to power Bryson's charging circuit from a USB port, teaching the convenience and desirability of charging portable devices over a single USB cable. Sherman also explained that while USB ports have nominal current limits, they provide a limited power resource, making an efficient switching regulator like Bryson's ideal for this application.
    • bqSWITCHER was introduced to provide well-known, practical implementation details for a USB charger. It taught features such as undervoltage lockout (UVLO) circuitry to protect the charger from low input voltage—a key consideration given the minimal voltage headroom of USB power noted by Sherman. It also disclosed a "precharge current" mode to safely revive deeply discharged batteries, a feature corresponding to limitations in dependent claims 22, 29, and 38.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine Bryson's adaptive charging circuit with Sherman's teachings to create a more convenient and commercially desirable product that charges from a ubiquitous USB port, thereby eliminating the need for a separate "wall wart" AC adapter. A POSITA would be further motivated to incorporate the teachings of bqSWITCHER to improve the reliability and functionality of such a USB charger by adding standard, necessary features like UVLO protection and pre-charge capabilities for lithium-ion batteries.
    • Expectation of Success: A POSITA would have a high expectation of success in making this combination. Bryson provided the fundamental power control topology, and Sherman confirmed the general feasibility of using efficient switching regulators with limited USB power. Furthermore, bqSWITCHER demonstrated a functionally similar buck regulator that successfully charges a lithium-ion cell from a supply voltage as low as 4.35V (the USB minimum), confirming that the low voltage headroom was a known and solvable engineering challenge.
    • Key Aspects: A central pillar of Petitioner's argument was that the patent examiner erroneously concluded during prosecution that Bryson did not disclose reducing charging current as battery voltage increases, thereby allowing the ’591 patent to issue.

4. Key Claim Construction Positions

  • "Coupled to" / "Coupling": Petitioner argued these terms should be given their plain meaning of being connected either directly or indirectly through other electronic components. This construction was asserted to be critical because it allows the prior art's use of intermediate components (e.g., sense resistors, filters) between two elements to satisfy the claimed "coupling" limitation.
  • Means-Plus-Function Terms: For "means for sensing the input current" (claim 35), Petitioner identified the corresponding structure as an input sense resistor (like RS1 in Bryson). For "means for sensing the output voltage on the battery" (claim 44), Petitioner identified the structure as a battery sense terminal or input, mapping this function to terminals on the amplifiers in Bryson's circuit. Petitioner argued these prior art structures were identical to those disclosed in the ’591 patent's specification.

5. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1-5, 7, 8, 10-13, 15-39, and 42-45 of the ’591 patent as unpatentable.