DCT
1:25-cv-00415
Psemi Corp v. Cirrus Logic Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: pSemi Corp. (Delaware)
- Defendant: Cirrus Logic, Inc. (Delaware) and Lion Semiconductor Inc. (Delaware)
- Plaintiff’s Counsel: Quinn Emanuel Urquhart & Sullivan, LLP
- Case Identification: 1:25-cv-00415, D. Del., 04/02/2025
- Venue Allegations: Plaintiff alleges venue is proper in the District of Delaware because both Defendants are Delaware corporations and therefore reside in the district.
- Core Dispute: Plaintiff alleges that Defendants’ LN8411 integrated circuit, a switched-capacitor power converter, infringes three patents related to circuit protection and power supply architectures.
- Technical Context: The technology concerns switched-capacitor power converters, which are critical for managing power efficiently in space-constrained electronics like smartphones by offering higher power density than traditional inductor-based converters.
- Key Procedural History: The complaint notes that Plaintiff pSemi acquired Arctic Sand Technologies Inc., an MIT spin-out, in March 2017 to bolster its intellectual property in switched capacitor technology. It also states that Defendant Cirrus Logic acquired Defendant Lion Semiconductor in 2021. No prior litigation or post-grant proceedings are mentioned in the complaint.
Case Timeline
| Date | Event |
|---|---|
| 2013-03-15 | Earliest Priority Date for ’438 and ’010 Patents |
| 2014-05-13 | Earliest Priority Date for ’232 Patent |
| 2021-01-01 | Cirrus Logic acquires Lion Semiconductor (approx. date) |
| 2024-10-08 | U.S. Patent No. 12,113,438 Issues |
| 2024-11-12 | U.S. Patent No. 12,143,010 Issues |
| 2025-01-28 | U.S. Patent No. 12,212,232 Issues |
| 2025-04-02 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 12,113,438 - "Protection of Switched Capacitor Power Converter"
The Invention Explained
- Problem Addressed: The patent’s background section describes the risk of damage to low-voltage transistors used in switched capacitor power converters, which can experience temporary over-voltage stress if the high-voltage input suddenly increases, potentially causing circuit failure (’438 Patent, col. 3:9-19).
- The Patented Solution: The invention proposes an integrated circuit with a fault detector that monitors the voltage or current at an "internal node" within the converter, such as a connection point between switches and capacitors (’438 Patent, col. 18:12-16). If a measurement deviates from a predetermined range, indicating a fault, the detector generates a signal that can be used to alter the converter’s operation and protect the components (’438 Patent, Abstract; Fig. 6).
- Technical Importance: This approach provides a mechanism for real-time monitoring and protection within the integrated circuit itself, enhancing the reliability of high-efficiency power converters that use sensitive, low-voltage components (Compl. ¶¶9, 13-14).
Key Claims at a Glance
- The complaint asserts independent claim 1 (’438 Patent, col. 18:11-34; Compl. ¶18).
- Essential Elements of Claim 1:
- An integrated circuit (IC) comprising a fault detector configured to sense a voltage and/or current at an internal node of a voltage converter.
- The voltage converter comprises a plurality of switches operable to selectively charge and/or discharge one or more capacitors to convert an input voltage to an output voltage.
- The internal node is disposed between a first pair of switches.
- The fault detector is configured to detect one or more fault events of the switching configuration at the internal node and to generate one or more corresponding fault signals.
- The complaint does not explicitly reserve the right to assert dependent claims for this patent.
U.S. Patent No. 12,143,010 - "Protection of Switched Capacitor Power Converter"
The Invention Explained
- Problem Addressed: The patent identifies an inefficiency in conventional switched capacitor converters where, during startup, certain switches must be rated to handle the full input voltage (’010 Patent, col. 9:18-24). Using high-voltage-rated switches for functions that normally only see low voltages reduces efficiency and increases die size (’010 Patent, col. 2:50-55).
- The Patented Solution: The invention introduces a dedicated "disconnect switch" with a high drain-to-source (DS) voltage rating, greater than both the input voltage and the rating of other switches in the converter (’010 Patent, col. 18:65-col. 19:5). This switch manages high-voltage transients (e.g., during power-up) and disconnects the input voltage upon receiving a fault signal, thereby protecting the other, more efficient low-voltage switches that perform the primary conversion function (’010 Patent, Abstract; col. 9:35-46).
- Technical Importance: This architecture isolates the high-voltage handling capability to a single component, allowing the main power conversion switches to be optimized for low-voltage, high-efficiency operation, which improves overall power density (Compl. ¶¶13-14).
Key Claims at a Glance
- The complaint asserts independent claim 1 (’010 Patent, col. 18:50-col. 19:9; Compl. ¶33).
- Essential Elements of Claim 1:
- An integrated circuit (IC) comprising a set of switches forming at least part of a step-down voltage converter, and a fault detector that generates fault signals.
- The set of switches is configured to couple to capacitors to perform voltage conversion.
- A "disconnect switch" is configured to have a DS voltage rating greater than the input voltage and greater than the DS voltage rating of at least one other switch in the set.
- The disconnect switch is configured to open and electrically disconnect the input voltage from at least one switch in the set, based on the one or more fault signals.
- The complaint does not explicitly reserve the right to assert dependent claims for this patent.
U.S. Patent No. 12,212,232 - "Power Supply for Gate Driver in Switched-Capacitor Circuit"
Technology Synopsis
The patent describes an apparatus for efficiently powering the gate drivers that control the switches in a switched-capacitor circuit (’232 Patent, Abstract). The invention uses the charge stored on the converter's own "flying capacitors" to power the gate drivers, which avoids the need for separate, complex power supply circuitry and allows for more compact and efficient designs (’232 Patent, col. 5:6-14).
Asserted Claims
The infringement count heading asserts claim 22, while the body of the complaint refers to allegations mapping to claim 41 (Compl. ¶¶50-51).
Accused Features
The complaint alleges that the LN8411 infringes by using a "mirror image arrangement" of gate drivers, switches, and flying capacitors (Compl. ¶58). This arrangement allegedly connects switches between flying capacitors, output terminals, and ground terminals in a manner that satisfies the patent's claims regarding how gate drivers are supplied with voltage from the flying capacitors themselves (Compl. ¶¶53-57).
III. The Accused Instrumentality
Product Identification
- The accused product is the Lion Semi / Cirrus Logic LN8411 integrated circuit (Compl. ¶18, ¶33, ¶50).
Functionality and Market Context
- The complaint identifies the LN8411 as a "Battery Management 4:1 switched-cap charger" (Compl. p. 6). This functionality places it in the category of switched capacitor power converters designed for consumer electronics (Compl. ¶¶10-14).
- The complaint alleges the LN8411 is offered for sale in the United States through electronics distributors such as Mouser and provides a screenshot of a product listing as evidence (Compl. ¶18, p. 6).
- The complaint also presents detailed, annotated schematics and integrated circuit layout diagrams allegedly corresponding to the LN8411 to illustrate its internal operation (Compl. ¶¶22, 37, 53). One such schematic, labeled "Image of LN8411 Schematics (annotated)," depicts the circuit's internal voltage converter and fault detector components (Compl. p. 9).
IV. Analysis of Infringement Allegations
'438 Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a fault detector configured to sense a voltage and/or current at an internal node of a voltage converter... | The LN8411 allegedly includes a component labeled "fault detector" that is connected to and senses conditions at an "internal node" of its voltage converter. | ¶22, ¶25 | col. 18:12-16 |
| the voltage converter comprising a plurality of switches...operable to selectively charge and/or discharge one or more of a plurality of capacitors... | The LN8411’s voltage converter contains a "plurality of switches" that connect to a "plurality of capacitors" to perform voltage conversion. | ¶23, ¶24 | col. 18:17-26 |
| wherein the internal node is disposed between a first pair of switches of the plurality of switches... | The complaint provides an annotated schematic purporting to show the sensed internal node is located between a first pair of switches in the LN8411 circuit. | ¶25 | col. 18:27-29 |
| wherein the fault detector is configured to detect one or more fault events...and to generate one or more fault signals... | The LN8411's fault detector is allegedly configured to detect fault events and generate "fault signals" as a result. | ¶27, ¶28 | col. 18:30-34 |
Identified Points of Contention
- Scope Questions: A central question may be the construction of "fault event." The infringement analysis may turn on whether the accused detector, which monitors voltage or current, is shown to detect a "fault event of the switching configuration" as contemplated by the patent, or merely performs routine operational monitoring that falls outside the claim's scope.
- Technical Questions: What is the precise function of the circuit block labeled "fault detector" in the complaint's schematics (Compl. p. 9)? Evidentiary discovery will be needed to determine if this block's actual operation—sensing a condition and generating a "fault signal"—matches the specific functions required by the claim language and described in the ’438 patent's specification.
'010 Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a set of switches configured to form at least a portion of a step-down voltage converter; | The LN8411 is alleged to comprise a set of switches that form a step-down voltage converter. | ¶37 | col. 18:51-53 |
| a fault detector configured to detect one or more fault events...and configured to generate one or more fault signals... | The LN8411 allegedly includes a fault detector that detects fault events during operation and generates fault signals. | ¶38 | col. 18:54-58 |
| a disconnect switch configured to have a drain-to-source (DS) voltage rating greater than an input voltage...and greater than a DS voltage rating of at least one switch in the set of switches... | The complaint alleges the LN8411 contains a "disconnect switch" whose DS voltage rating is greater than both the input voltage and the rating of other switches in the converter, referencing annotated schematics and an integrated circuit layout with a driver size table. | ¶42, ¶43 | col. 18:65-19:5 |
| wherein the disconnect switch is configured, based on the one or more fault signals, to open to electrically disconnect the input voltage from the at least one switch... | The disconnect switch is allegedly configured to open in response to fault signals, thereby disconnecting the input voltage from other switches. | ¶44, ¶45 | col. 19:6-9 |
Identified Points of Contention
- Scope Questions: The definition of "disconnect switch" will be a focal point. The analysis will question whether the term requires a specific structure or is defined purely by its functional characteristics: having a superior DS voltage rating and operating to disconnect the input voltage based on fault signals.
- Technical Questions: Does the accused component identified in the complaint's annotated integrated circuit diagram (Compl. p. 20) actually possess a DS voltage rating greater than both the converter's input voltage and another switch in the set? This allegation relies on interpreting a "Driver Size" table provided in the complaint and will require technical evidence to substantiate.
V. Key Claim Terms for Construction
Term: "internal node" ('438 Patent)
- Context and Importance: The location of the fault sensing is a key limitation. The definition of "internal node" will determine where in the accused circuit the alleged sensing must occur to infringe. Practitioners may focus on this term because the defense could argue it is limited to specific types of nodes shown in the patent's embodiments.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: Claim 1 defines the term by its location—"of a voltage converter" and "disposed between a first pair of switches" (’438 Patent, col. 18:13-29). This suggests any node meeting that topological requirement could qualify.
- Evidence for a Narrower Interpretation: The specification's primary embodiment for fault detection, Figure 6, shows the sensing circuitry connected to a node that is also a terminal of a capacitor (’438 Patent, Fig. 6). This could be used to argue that an "internal node" must be a capacitor terminal or "phase node."
Term: "disconnect switch" ('010 Patent)
- Context and Importance: This is the central element of the asserted claim in the ’010 patent. Infringement depends entirely on whether the accused LN8411 is found to contain a component that meets this definition.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim defines the term functionally by its DS voltage rating ("greater than an input voltage... and greater than a DS voltage rating of at least one switch") and its action ("to open to electrically disconnect the input voltage") (’010 Patent, col. 18:65-col. 19:9). This may support a construction covering any switch that performs this function, regardless of its primary purpose.
- Evidence for a Narrower Interpretation: The specification describes the disconnect switch in the context of managing voltages "During powerup" and protecting against faults to allow other switches to be low-voltage designs (’010 Patent, col. 9:40-46). This language about purpose could support a narrower construction limited to switches intended for startup and fault protection, as opposed to a switch that may serve other primary functions.
VI. Other Allegations
Indirect Infringement
- The complaint alleges induced infringement for all three patents. It asserts that Defendants, with knowledge of the patents, intentionally encourage infringement by providing customers with data sheets, instructional materials, and technical assistance for integrating and operating the accused LN8411 product in an infringing manner (Compl. ¶29, ¶46, ¶59).
Willful Infringement
- The complaint alleges that Defendants' infringement is willful, asserting that they have had "actual knowledge" of the patents and the resulting infringement "since at least the date of this filing" (Compl. ¶29, ¶46, ¶59). This suggests an allegation of post-suit willfulness.
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope: How will the court construe the term "fault event" in the ’438 patent? The case may turn on whether the accused LN8411's monitoring circuit is found to detect specific "fault events of the switching configuration," as detailed in the patent, or if it performs more general operational control that falls outside a reasonable construction of the claim.
- A key technical question will be one of comparative properties: Does the accused component identified as a "disconnect switch" in the LN8411 actually possess the dual-comparative drain-to-source voltage rating required by claim 1 of the ’010 patent—i.e., a rating greater than both the converter's input voltage and the rating of at least one other switch in the circuit?
- The case will also present an evidentiary challenge: The complaint relies heavily on annotated schematics and layout diagrams to map claim limitations to the accused device's internal structure. A central question will be what further evidence is required to prove that these diagrams accurately reflect the LN8411's physical structure and that the labeled components perform the specific functions required by the claims.