Resistor-less USB Adapter Protection Circuit
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Solution Overview
Problem
Existing protection systems for electronic devices and USB connectors are inefficient and costly due to the need for current sense resistors, which can lead to damage from excessive power loss and potential fires when low impedance is detected, and are not compatible with both modern and legacy devices.
Innovation Solution
A resistor-less USB protection system that detects parasitic impedance between pins and uses a switch to disconnect the current path when abnormally low impedance is detected, without adding a current sense resistance in the return path, ensuring efficient and cost-effective protection for a wide range of electronic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current sense resistor is added to detect low impedance in existing protection systems, then damage from excessive power loss can be prevented, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the impedance detection function from the return path by using the sense pin and data pins, eliminating the need for a current sense resistor in the ground path. This reduces device complexity while maintaining protection reliability through alternative detection methodology.
Solution Approach 2:
The patent introduces an intermediary detection path using the sense pin and data pins to measure impedance between VBUS and GND. This intermediary measurement path allows impedance detection without adding components to the main power return path, resolving the contradiction between reliability and complexity.
2Reliability
If a current sense resistor is added to detect low impedance, then protection against fires can be provided, but the manufacturing cost increases
Solution Approach 1:
The patent removes the need for additional current sense resistors by utilizing existing sense and data pins for impedance detection. This extraction approach maintains fire protection capability while eliminating the cost of additional components and their associated assembly processes.
Solution Approach 2:
The patent enables the USB connector to self-diagnose impedance issues using its own sense and data pins without requiring external sensing components. This self-service approach reduces manufacturing costs by eliminating the need for additional protective components while maintaining safety functionality.
3Reliability
If a current sense resistor is added to the return path, then impedance detection can be achieved, but compatibility with legacy devices is lost
Solution Approach 1:
The patent makes the sense and data pins serve multiple functions: normal data communication and impedance detection. This multi-functionality allows impedance detection capability without adding dedicated sensing components that would reduce compatibility with legacy devices, as the existing pins are already present in both modern and legacy USB implementations.
Solution Approach 2:
The patent uses the sense pin and data pins as intermediary elements for impedance detection without modifying the main power and ground paths. This intermediary approach maintains compatibility with legacy devices since it utilizes existing pins that are part of the standard USB specification, rather than requiring modifications to the power return path.
4Reliability
If existing protection systems use current sense resistors, then power loss damage can be prevented, but the system efficiency decreases
Solution Approach 1:
The patent extracts the detection function from the power return path by using sense and data pins, eliminating the need for a current sense resistor that would continuously consume power. This extraction maintains damage prevention capability while improving system efficiency by removing the parasitic resistance from the power path.
Solution Approach 2:
The patent applies detection only when needed through controlled activation of the impedance detection circuit, rather than continuously monitoring through a permanent current sense resistor. This partial action approach maintains protection reliability while minimizing energy loss by activating detection only during relevant operational states.
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
The system effectively prevents damage to USB connectors and electronic devices by detecting low impedance and disconnecting the power path, maintaining efficiency and compatibility with both modern and legacy devices, thus reducing the risk of overheating and fires.
Implementation Method 1
detect a voltage across a parasitic impedance between first and second pins of the standard connector
Implementation Method 2
remove a current path between the power source and a supply pin of the standard connector
Implementation Method 3
if the power through these cables or connectors becomes too high, the cables, connectors, or coupled devices can be damaged, even melting or catching fire
Data Source
AI summary
This document discusses, among other things, a protection system and method configured to detect a parasitic impedance between first and second pins of a standard connector and to remove a current path between a power source and a supply pin of the standard connector if a low-impedance is detected, in certain examples, without adding a current sense resistance to a return path between a ground pin of the standard connector and the power source.