USB-C Connector Tongue Contact Length Variation for Disconnect Sequence

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Solution Overview

Problem

Conventional USB-C connector receptacles face issues where VBUS power is applied to electronic devices after ground disconnection, leading to potential damage due to transient current pathways, especially when EMI contacts engage signal pins during connector removal, causing high currents to flow through ESD diodes.

Innovation Solution

Modifying the USB-C connector receptacle tongue by adjusting the lengths and positions of VBUS power, ground, and signal contacts to ensure simultaneous disconnection, incorporating increased capacitance on the VBUS line, and using flexible ground contacts to maintain a ground path until VBUS power is fully disconnected, along with AC coupling to prevent direct DC voltage application to signal pins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If VBUS power contacts and ground contacts are placed at the same distance from the front of the connector receptacle tongue, then simultaneous disconnection occurs, but variations in contact lengths may still result in power being applied after ground disconnection

Engineering Contradiction:

Improvedisconnection sequence reliabilityVSAvoidcontact length variation tolerance

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies different length specifications to different contact types. VBUS power contacts are made shorter than ground contacts, creating a local quality difference that ensures ground contacts maintain connection longer during disconnection. This resolves the contradiction by making the disconnection sequence reliable regardless of manufacturing variations in contact lengths.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent designs the contact lengths in advance such that ground contacts extend further than VBUS power contacts. This preliminary configuration ensures that during insertion, ground connection is established before power connection, and during removal, ground disconnection occurs after power disconnection, preventing the harmful transient condition.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If ground contacts are extended closer to the front edge of the tongue, then ground path is maintained longer during disconnect, but the protective covering layer becomes narrower and more susceptible to damage

Engineering Contradiction:

Improveground path continuityVSAvoidprotective covering durability

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent optimizes the parameters of contact lengths and positions to achieve the desired ground path continuity while maintaining adequate protective covering. By carefully selecting the extension distance of ground contacts relative to VBUS contacts, the patent balances the need for reliable ground connection during disconnection against the need to protect the covering layer from mechanical damage.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If VBUS power contacts are shortened to the same length as signal contacts, then power is removed before ground, but signal contacts may be closer to the front edge causing high voltage on signal pins without VBUS power

Engineering Contradiction:

Improvepower removal sequenceVSAvoidhigh voltage on signal pins

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces capacitance on the VBUS line as an intermediary element that helps maintain power during the transient disconnection period. This capacitance acts as a buffer, ensuring that the integrated circuit remains powered long enough to tolerate any high voltage on signal pins without damage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Prevents damage to ESD diodes and related components by ensuring power is removed before ground, maintaining a stable ground path, and tolerating high input voltages without applying VBUS power, thus reducing the risk of component damage during connector disconnection.

Implementation Method 1

Embodiments of the present invention may provide an increased capacitance on the VBUS power line in order to power the input component during a disconnect after the VBUS power is removed

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

current may flow from the VBUS power supply, through an electrostatic-discharge (ESD) diode that is integrated on an integrated circuit connected to the connector receptacle

Methodology Applied

Scientific EffectElectrostatic Discharge: Electrostatic Discharge

Data Source

PatentUS10084269B2Variations in USB-C contact length to improve disconnect sequence

Publication Date: 2018.09.25 APPLE INC

AI summary

Connector receptacle tongues having contacts arranged to disconnect from corresponding contacts in a connector insert in such a way that undesirable current pathways that damage electrical components associated with the connector receptacle are avoided. Other examples include connector receptacles having a tongue in a passage and ground spring contacts located in openings in sides of the passage, where the ground spring contacts connect to a shield of a connector insert such that these undesirable current pathways are avoided.