USB-C Port Short Protection Using Thermistor-Gated FET Cutoff
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Solution Overview
Problem
The increased power delivery capabilities of USB Type-C connectors pose safety risks due to potential short circuits, which can lead to overheating and damage to the port or connected components, as well as risk of user injury from excessive heat.
Innovation Solution
A short circuit protection circuit utilizing a voltage divider with a thermistor and a field-effect transistor (FET) that turns off power delivery when a short circuit is detected, preventing excessive heat buildup by mimicking a disconnected state when the thermistor heats up beyond a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If USB Type-C port delivers high power (up to 100 watts), then power delivery capability is improved, but safety risk increases due to potential short circuits causing overheating and damage
Solution Approach 1:
The patent implements preliminary protective actions by configuring the FET and voltage divider circuit before power delivery begins. The FET is positioned to automatically interrupt power flow if abnormal conditions occur, and the voltage divider is pre-configured to monitor voltage levels. This preliminary setup ensures that protection mechanisms are in place before the harmful short circuit condition can develop, resolving the contradiction by enabling high power delivery while pre-establishing safety safeguards.
Solution Approach 2:
The patent introduces intermediary components between the power source and the USB Type-C port to mediate power delivery and provide protection. The FET acts as an intermediary switch that can interrupt power flow, while the voltage divider and resistor network serve as intermediary monitoring elements. These intermediaries enable high power delivery capability while providing layers of protection against short circuits, thus resolving the safety risk contradiction.
2Object-affected harmful factors
If USB Type-C port is monitored for short circuit conditions, then safety is improved, but device complexity increases due to additional protection circuitry
Solution Approach 1:
The patent merges the protection function with existing USB Type-C port infrastructure. The FET is integrated into the power delivery path, and the voltage divider utilizes existing configuration channel lines (CC1/CC2) and ground connections. By combining protection components with existing port structures rather than adding completely separate monitoring systems, the patent improves safety while minimizing the increase in device complexity.
Solution Approach 2:
The protection circuit is designed to be self-monitoring and self-actuating. The voltage divider automatically detects voltage changes indicating short circuit conditions, and the FET automatically interrupts power flow without requiring external control signals. This self-service mechanism improves safety while avoiding the complexity of external control systems, microcontroller intervention, or additional sensing circuits.
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
Effectively reduces the risk of port damage and user injury by ensuring power delivery is halted in case of a short circuit, maintaining safety while allowing power delivery within safe temperature ranges.
Implementation Method 1
a voltage divider connected to a junction point on the first configuration channel line, the voltage divider comprising a second resistor and a thermistor
Implementation Method 2
a field effect transistor (FET) comprising a source, gate, and drain, wherein the drain is connected to the first resistor, the source is connected to the ground line, and the gate is connected to a second junction point between the second resistor and thermistor of the voltage divider
Implementation Method 3
a voltage divider connected to a junction point on the first configuration channel line, the voltage divider comprising a second resistor and a thermistor
Data Source
AI summary
A short circuit protection circuit may comprise a first configuration channel line extending from a first connector, a first resistor connected to the first configuration channel line; a voltage divider connected to a junction point on the first configuration channel line, the voltage divider comprising a second resistor and a thermistor, and a field effect transistor (FET) comprising a source, gate, and drain. The thermistor may be connected to a ground line. The drain of the FET may be connected to the first resistor, the source of the FET may be connected to the ground line, and the gate of the FET may be connected to a second junction point between the second resistor and thermistor of the voltage divider.