USB Plug Connector Thermal Protection Circuit Design
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Solution Overview
Problem
The existing cable connector with a thermal protection circuit does not efficiently conduct heat from the fitting portion to the temperature sensing element, leading to insensitive cutoff of current supply during abnormal heating.
Innovation Solution
A plug connector design featuring a printed circuit board with a heat conduction pattern that conducts heat from the metal shell to a temperature switch IC, including a temperature switch IC and an FET to cut off power supply when excessive temperature is detected, eliminating the need for additional heat conductive members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal protection circuit is mounted on a printed circuit board in the connector, then the circuit can detect temperature and cut off power supply, but the heat conduction from the fitting portion to the temperature sensing element is insufficient, resulting in insensitive detection of abnormal heating
Solution Approach 1:
A heat conduction member (thermal paste or heat conduction plate) is introduced as an intermediary between the fitting portion and the temperature sensing element. This mediator efficiently transfers heat from the fitting portion where abnormal heating occurs to the temperature sensing element, enabling sensitive detection of temperature changes without requiring the sensing element to be in direct contact with the fitting portion.
Solution Approach 2:
The temperature sensing element is extracted from direct integration with the fitting portion and instead positioned on the printed circuit board, with heat conduction established through a dedicated heat conduction path. This separation allows the sensing element to be positioned optimally for circuit integration while maintaining high temperature detection sensitivity through the heat conduction member.
2Measurement precision
If additional heat conductive members are added to improve heat conduction, then temperature detection sensitivity improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The heat conduction member serves multiple functions: it acts as a thermal interface material for heat transfer, provides thermal bonding between components, and can serve as a filling material for gaps between the fitting portion and the temperature sensing element. This multi-functionality reduces the need for additional separate components while achieving effective heat conduction.
Solution Approach 2:
The invention changes the thermal conductivity parameter of the interface between the fitting portion and temperature sensing element by introducing a high thermal conductivity heat conduction member. This parameter change enables effective heat transfer without requiring complex mechanical or structural modifications to the connector design.
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 sensitive cutoff of current supply during abnormal heating in the fitting portion with the counter connector, effectively protecting against overheating without requiring additional heat conductive components.
Implementation Method 1
the printed circuit board comprises a heat conduction pattern which conducts heat of the metal shell to the temperature switch IC
Implementation Method 2
a temperature switch IC which detects a temperature
Implementation Method 3
an FET which is disposed in a power supply wiring of the printed circuit board, and, when a detected temperature of the temperature switch IC exceeds a predetermined temperature, causes the FET to cut off the power supply wiring
Data Source
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AI summary
The invention provides a plug connector which, when abnormal heating occurs in a fitting portion with a counter connector, can sensitively cut off the current supply. The plug connector has: contacts 30; a body 50 which holds the contacts 30; a metal shell 60 which covers the body 50; and a printed circuit board 70 on which the contacts 30 are solder-connected. The body 50 has a fitting portion 52 with a counter connector. The board 70 has a thermal protection circuit 80. The thermal protection circuit 80 has a temperature switch IC 90 which detects a temperature, and an FET 100 which is disposed in a power supply wiring of the board 70. When the detected temperature of the temperature switch IC 90 exceeds a predetermined temperature, the power supply wiring is cut off by the FET 100. In the plug connector, the board 70 has a heat conduction pattern 110 which conducts heat of the metal shell 60 to the temperature switch IC.