USB Circuit Device Disconnection Detection

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Solution Overview

Problem

Existing USB communication systems face complications in accurately detecting device disconnection due to increased amplitude levels, leading to erroneous disconnection determinations, particularly when the amplitude exceeds the disconnection detection level, and require complex configurations to adjust the disconnection detection level.

Innovation Solution

A circuit device with a packet output circuit, detection circuit, and determination circuit that amplifies packets for USB-compliant buses, detects amplitude levels, and adjusts the current for SOF packet outputs to prevent erroneous disconnection determinations by setting the amplitude level of the End of Packet (EOP) below the disconnection threshold, allowing for accurate device connection status assessment without altering the disconnection detection level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the amplitude level of signals is increased to compensate for attenuation in USB transmission, then signal transmission quality is improved, but erroneous disconnection detection occurs when the amplitude exceeds the disconnection detection level

Engineering Contradiction:

Improvesignal transmission qualityVSAvoiddisconnection detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The packet structure is segmented into specific sections (EOP and non-EOP sections), and different current levels are applied to different sections. The EOP section uses a lower current level than other sections, allowing the overall signal amplitude to be high enough for reliable transmission while the EOP section remains below the disconnection detection threshold.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the packet signal have different current levels applied locally. The EOP section specifically uses a lower current level (first current level) compared to other packet sections (second current level), creating local quality differentiation that prevents erroneous disconnection detection in the EOP section while maintaining high amplitude elsewhere for reliable transmission.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If the disconnection detection level is increased to accommodate higher amplitude levels, then erroneous disconnection detection is prevented, but the configuration becomes complicated requiring multiple reference voltages and selection mechanisms

Engineering Contradiction:

Improvedisconnection detection accuracyVSAvoidconfiguration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary action by setting different current levels for different packet sections in advance, specifically lowering the current level for the EOP section before transmission. This preliminary differentiation of current levels allows the use of a fixed disconnection detection level without requiring dynamic adjustment or multiple reference voltages, thereby preventing erroneous detection while maintaining simple configuration.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of increasing the disconnection detection level to match the higher signal amplitude (the conventional approach), the invention inverts the approach by lowering the signal amplitude specifically in the EOP section while maintaining high amplitude in other sections. This inversion allows the use of a standard disconnection detection level without modification, avoiding the complexity of multiple reference voltages and selection mechanisms.

Inventive Principle:

Principle #13The other way round (Inversion)

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 erroneous disconnection determinations and simplifies the configuration by maintaining accurate device connection status assessment, even with high-quality eye-patterns and large signal amplitudes, ensuring uninterrupted operation between USB Host and Device in HS mode.

Implementation Method 1

a packet output circuit configured to amplify a current for a packet and output the packet to a USB-compliant bus

Methodology Applied

Scientific EffectSignal amplification:

Implementation Method 2

a detection circuit configured to detect whether an amplitude level of the packet transmitted to the bus has exceeded a disconnection detection level

Methodology Applied

Scientific EffectVoltage level detection:

Data Source

PatentUS11126582B2Circuit device, determination method for circuit device, and electronic apparatus

Publication Date: 2021.09.21 SEIKO EPSON CORP

AI summary

A circuit device includes a packet output circuit configured to amplify a current for a packet and output the packet to a USB-compliant bus, a detection circuit configured to detect whether an amplitude level of the packet transmitted to the bus has exceeded a disconnection detection level for a prescribed time period, a determination circuit configured to set a current for an EOP of an SOF packet output by the packet output circuit to lower than a current for a section other than the EOP, and when it is detected, by the detection circuit, that an amplitude level of the EOP has exceeded the disconnection detection level, determine that a device that was connected to the bus is disconnected.