USB-C Impedance Control Circuit for Deadlock-Free Connection Detection

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Solution Overview

Problem

In Type-C USB systems, a deadlock occurs when a device cannot switch its resistor configuration without receiving power, leading to undetected connections and system failures due to mismatched impedance detection.

Innovation Solution

An impedance control circuit comprising a configuration channel interface, resistors, and transistors that automatically adjust impedance to ensure proper connection detection and power delivery by using transistors with different threshold voltages and resistors to maintain stable impedance, even without external power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a device couples a resistor to the configuration channel interface without receiving power, then the device can establish impedance configuration, but the device cannot switch its resistor configuration without power, leading to connection detection failure

Engineering Contradiction:

Improveconnection detection reliabilityVSAvoidresistor switching capability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies preliminary action by pre-configuring the impedance control circuit with multiple resistors (Rp1, Rd1, Rp2, Rd2) and transistors that can automatically switch impedance states. The circuit is designed to detect voltage levels and automatically configure the appropriate resistor configuration before power delivery is fully established, allowing the device to be detected and powered without manual intervention or deadlock

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The impedance control circuit performs self-service by automatically detecting the voltage level at the configuration channel interface and switching between different resistor configurations without external control. The transistors (M1, M2) are controlled by voltage thresholds to automatically select the appropriate impedance state, enabling the circuit to serve itself in establishing proper connection detection and power delivery conditions

Inventive Principle:

Principle #25Self-service

2Adaptability or versatility

If both devices use symmetric fool-proof structure with configurable resistors, then the system supports versatile data transmission applications, but impedance mismatch occurs when resistor configurations are not properly coordinated, causing connection confirmation failure

Engineering Contradiction:

Improvedata transmission application supportVSAvoidimpedance matching reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements feedback by having each device monitor the voltage level at its configuration channel interface and adjust its resistor configuration accordingly. The voltage detection mechanism provides feedback about the connection state, and the impedance control circuit responds by switching resistors to achieve proper impedance matching, ensuring reliable connection confirmation while supporting versatile applications

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies parameter changes by dynamically switching between different resistor values (high impedance Rp1/Rp2 and low impedance Rd1/Rd2) based on the detected voltage level. This allows the impedance parameter to be adjusted in real-time to match the connection requirements, resolving the contradiction between versatility and impedance matching reliability

Inventive Principle:

Principle #35Parameter changes

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

Enables successful connection confirmation and power provision between USB devices, preventing deadlocks and ensuring stable impedance for subsequent operations, regardless of power configuration.

Implementation Method 1

using transistors with different threshold voltages and resistors to maintain stable impedance

Methodology Applied

Scientific EffectTransistor threshold voltage effect:

Data Source

PatentUS11791801B2Impedance control circuit capable of confirming connection status

Publication Date: 2023.10.17 REALTEK SEMICON CORP

AI summary

An impedance control circuit includes a configuration channel interface, three resistors and two transistors. The configuration channel interface is coupled to a universal serial bus device. The first resistor has a first terminal coupled to the configuration channel interface. The first transistor has a first terminal coupled to a second terminal of the first resistor, and a second terminal coupled to a system voltage terminal. The second transistor has a first terminal coupled to the second terminal of the first resistor, and a second terminal coupled to the system voltage terminal. The second resistor has a first terminal coupled to the second terminal of the first resistor, and a second terminal coupled to a control terminal of the second transistor. The third resistor has a first terminal coupled to the second terminal of the second resistor, and a second terminal coupled to the system voltage terminal.