USB-C Cable Thermal Protection Using CC Line Disconnect
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Solution Overview
Problem
High-power USB-C cables face challenges in thermal protection due to the impracticality of using large and expensive positive temperature coefficient (PTC) elements to prevent overheating, which is exacerbated by suboptimal connectivity issues such as dirty or bent pins.
Innovation Solution
Implementing PTC elements on non-power conductors like the configuration channel (CC) and Vconn conductors within USB-C cables, which increase resistance and arrest current flow when temperatures exceed a trip point, allowing for compact and cost-effective thermal protection without affecting power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTC elements are used for thermal protection in high-power USB-C cables, then overheating protection is improved, but the size and cost of the cable increase significantly
Solution Approach 1:
The cable is divided into multiple functional segments: power conductors for high-current transmission, control conductors for device communication, and temperature sensing elements distributed at strategic locations. This segmentation allows thermal protection without requiring a single large PTC element that would dominate the cable volume.
Solution Approach 2:
Temperature sensing elements act as intermediaries between the power conductors and the control circuitry. These sensors detect thermal conditions and communicate status to devices, which then adjust power delivery accordingly. This intermediary approach enables protection without directly interrupting power flow through large PTC elements.
2Reliability
If PTC elements are used for thermal protection in high-power USB-C cables, then overheating protection is improved, but the cost of the cable increases significantly
Solution Approach 1:
The patent employs inexpensive temperature sensing elements and control circuitry that can be easily replaced or reset, rather than relying on expensive PTC elements. The sensing elements are designed to be cost-effective components that provide adequate protection without the high cost of power-rated PTC devices.
Solution Approach 2:
The patent replaces the mechanical/physical PTC element approach with an electronic sensing and control system. Instead of relying on the physical expansion and resistance change of PTC materials, the system uses temperature sensors and digital communication to achieve thermal protection, reducing component costs.
3Reliability
If PTC elements are placed on power conductors, then thermal protection is effective, but power transmission is affected
Solution Approach 1:
Temperature sensing elements are placed in thermal contact with power conductors but are electrically isolated from them. The sensing elements monitor temperature without being part of the high-current power path, allowing accurate thermal detection without interfering with power transmission capability.
Solution Approach 2:
The protection function is segmented into separate sensing and control components rather than using a single PTC element in the power path. This allows the power conductors to maintain their full transmission capability while separate sensing elements provide thermal monitoring.
4Reliability
If the cable appears disconnected to devices during fault conditions, then safety is improved, but data communication is interrupted
Solution Approach 1:
The cable's operational state is made dynamic rather than static. The control circuitry can adjust the cable's appearance to devices in real-time based on thermal conditions, transitioning between full power mode, reduced power mode, and disconnected mode as needed. This dynamic control allows selective interruption of power while maintaining data communication for status reporting.
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
This solution effectively mitigates overheating and thermal damage by allowing the cable to appear disconnected to devices when temperatures rise, preventing high-power operation in hazardous conditions and ensuring the PTC elements are small and inexpensive, making the solution commercially viable.
Implementation Method 1
a first protection circuit coupled to the first data conductor and associated with a first temperature sensing element, the first protection circuit configured to mitigate current flowing through the first data conductor if a temperature detected by the first temperature sensing element rises above a predefined first trip temperature
Implementation Method 2
associated with a first temperature sensing element, the first protection circuit configured to mitigate current flowing through the first data conductor if a temperature detected by the first temperature sensing element rises above a predefined first trip temperature
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A cable including a power conductor configured to transmit electrical power between a first device and a second device, a first data conductor configured to transmit data between the first device and the second device, and a first protection circuit coupled to the first data conductor and associated with a first temperature sensing element, the first protection circuit configured to mitigate current flowing through the first data conductor if a temperature detected by the first temperature sensing element rises above a predefined first trip temperature, wherein the opening of the first data line indicates a fault condition to a device to which the cable is connected, whereby electrical power flowing through the power conductor is resultantly mitigated.