USB Re-Driver Circuit for Cable Disconnect Detection

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Solution Overview

Problem

Electrical cables connecting USB compliant devices can become disconnected due to pulling, fraying, or failure, leading to communication issues and interoperability problems.

Innovation Solution

Implementing a re-driver circuit with detection circuitry that monitors peak voltage swings of data signals to detect cable disconnection, triggering a power-down mode when the cable becomes disconnected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the device remains in active state to maintain communication capability, then communication readiness is improved, but energy consumption increases and the device cannot detect cable disconnection promptly

Engineering Contradiction:

Improvecommunication readinessVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically transitions between active and power-down states based on cable connection status. The re-driver circuit is enabled during active communication and disabled during power-down mode, allowing the device to adapt its operational state to current needs while maintaining reliable communication when connected.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The detection circuitry continuously monitors the data signal characteristics and provides feedback to the state machine. When cable disconnection is detected through signal analysis, the system receives feedback to transition to power-down mode, ensuring reliable detection while managing energy consumption effectively.

Inventive Principle:

Principle #23Feedback

2Use of energy by moving object

If the device powers down to save energy, then energy consumption is reduced, but the device cannot detect cable disconnection and maintain USB compliance

Engineering Contradiction:

Improveenergy consumptionVSAvoidcable disconnection detection

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The detection circuitry performs preliminary monitoring of data signal characteristics before the device fully transitions to power-down mode. By analyzing voltage swing characteristics and signal presence in advance, the system can detect cable disconnection events and trigger appropriate state transitions while maintaining USB compliance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The re-driver circuit serves as an intermediary between the active communication interface and the power-down state. It can operate in a low-power monitoring mode that detects cable disconnection through signal characteristics while consuming minimal energy, bridging the gap between active communication and complete power-down.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If the detection circuitry monitors signal characteristics continuously, then cable disconnection detection accuracy is improved, but energy consumption and circuit complexity increase

Engineering Contradiction:

Improvecable disconnection detection accuracyVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The detection function is extracted as a separate, dedicated circuitry within the re-driver circuit. This specialized detection block focuses solely on analyzing data signal characteristics to determine cable connection status, simplifying the overall system by dedicating specific hardware to the detection task rather than requiring complex general-purpose monitoring.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The detection circuitry uses simplified signal characteristic analysis that mirrors the essential features of full signal monitoring. By detecting key parameters such as voltage swing presence and magnitude, the circuit achieves accurate cable disconnection detection with reduced complexity compared to continuous comprehensive signal analysis.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS12531408B2Disconnect detection circuitry for universal serial bus (USB) compliant electronic devices

Publication Date: 2026.01.20 APPLE INC

AI summary

Systems, methods, and apparatuses can detect whether an electrical cable between a source device and a sink device has become disconnected. The source device and/or the sink device can be compliant with a version of a Universal Serial Bus (USB) standard, for example, USB 3.x. These systems, methods, and apparatuses can monitor peak voltage swings of data signals flowing between the source device and the sink device. The peak voltage swing of these data signals can be at a first value when the electrical cable is connected to the source device and the sink device or at a second value greater than the first value when the electrical cable is disconnected from the source device or the sink device. The peak voltage swing can switch from the first value to the second value in response to the electrical cable being disconnected from the source device or the sink device. As such, these systems, methods, and apparatuses can determine that the electrical cable has become disconnected from the source device or the sink device in response to detecting the second value for the peak voltage swing of the data signals flowing from the source device to the sink device.