USB Type-C Sink Cable Detection Circuit Prevents Source Overload
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Solution Overview
Problem
When using USB Type-C legacy cables to connect a USB Type-C incompatible source to a USB Type-C compatible sink, the limited power tolerance can lead to excessive power reception, potentially overloading the source and causing faults, due to mismatched pull-up resistance values not meeting the USB standard.
Innovation Solution
An electronic device with detection circuits and controllers that determine the type of cable connected by monitoring the voltage of configuration channel terminals, allowing safe power reception without requesting excessive power from an external power supply by using appropriate resistors and switching mechanisms to confirm the connection status and power supply capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If USB Type-C legacy cables are used to connect USB Type-C incompatible source to USB Type-C compatible sink, then connectivity with existing USB ports is ensured, but power supply capability may be exceeded causing source overload and faults
Solution Approach 1:
The detection circuit performs preliminary detection of the CC terminal voltage before power supply operation to identify the cable type. This preliminary action allows the system to determine whether a legacy cable is connected and adjust power reception accordingly, preventing source overload before it occurs.
Solution Approach 2:
The system continuously monitors the CC terminal voltage and uses this feedback to determine cable type and adjust power reception requests. The controller modifies power reception behavior based on the detected voltage levels, creating a closed-loop control system that prevents exceeding power supply capability.
2Adaptability or versatility
If pull-up resistance value in legacy cable does not meet USB standard (less than 56 kΩ), then cable compatibility is maintained, but sink may require excessive power reception causing source fault
Solution Approach 1:
The detection circuit measures the CC terminal voltage before power supply to preliminarily identify whether the pull-up resistance meets the USB standard. This early detection allows the sink to adjust its power reception request accordingly, preventing excessive power demands that could cause source fault.
Solution Approach 2:
The system uses the detected CC terminal voltage as feedback to determine whether the cable compliance is proper. Based on this feedback, the controller adjusts power reception requests to match the actual power supply capability, preventing harmful excessive power reception.
3Reliability
If sink connects pull-up resistor to CC terminal to verify source power supply capability, then power reception safety is improved, but device complexity increases due to additional detection circuits and control logic
Solution Approach 1:
The detection circuit uses the existing CC terminal and its voltage detection capability for dual purposes: both for USB Type-C role identification and for legacy cable detection. This multi-functionality approach allows power supply capability verification without adding separate dedicated detection circuits, thereby reducing overall device complexity.
Solution Approach 2:
The system uses its own existing detection circuitry and the CC terminal voltage to self-verify the power supply capability. Rather than requiring external verification devices or complex additional circuits, the sink performs self-detection and self-adjustment of power reception based on the detected voltage levels.
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
Ensures safe power reception by accurately determining the type of USB cable and power supply capability, preventing source overload and ensuring compliance with USB standards, even when using non-compliant USB Type-C legacy cables.
Implementation Method 1
a detection circuit for detecting the voltage of the first and second terminals
Data Source
AI summary
To make an excessive power receiving request by a sink when a USB Type-C legacy cable is used. An electronic device includes a first and second terminals connected to a cable, a detection circuit for detecting the voltage of the first and second terminals, and a first or second terminal detected by the detection circuit. It is provided with a controller that determines the type of cable based on the terminal voltage and confirms the power supply capacity of the external electronic device connected via the cable according to the type of cable.