USB Type-C Over-Voltage Isolation Circuit for CC Pin Protection
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Solution Overview
Problem
USB Type-C ports lack effective over-voltage protection, particularly between the power bus pins and configuration channel pins, which can lead to short-circuiting and potential damage when users inadequately unplug devices, exceeding the recommended 5V voltage limit.
Innovation Solution
An over-voltage protection circuit is introduced, comprising a first node coupled to a supply voltage, a second node connected to a USB Type-C port pin, an over-voltage detection circuit, a switch, and a voltage generator. The circuit detects voltage levels, provides an over-voltage signal, and adjusts a switch control signal to operate the switch in a linear region for normal conditions and a saturation region during over-voltage events to cut off the signal transmission path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power bus pin VBUS is raised to 20V to meet USB power supply specification requirements, then the maximum current provided by the USB Type-C device is increased for optimizing power usage, but the risk of short-circuiting between adjacent pins increases when the user inadequately removes the sink device
Solution Approach 1:
The patent introduces an over-voltage protection circuit as an intermediary between the power bus pin and configuration channel pin. This circuit includes an over-voltage detection circuit that monitors voltage levels and a switch that isolates the pins when over-voltage is detected, preventing direct short-circuiting while allowing normal power transmission at elevated voltages
Solution Approach 2:
The over-voltage protection circuit performs preliminary protection by detecting voltage levels before dangerous short-circuiting can occur. The detection circuit continuously monitors the voltage on the configuration channel pin and prepares the switch to isolate the pins preemptively when over-voltage conditions are detected, preventing damage before it happens
2Ease of operation
If the power bus pin VBUS is short-circuited to the configuration channel pin due to inadequate unplugging, then the circuit connection is established, but over-voltage damage occurs exceeding the recommended 5V voltage limit
Solution Approach 1:
The protection circuit acts as an intermediary safeguard that operates automatically during plug/unplug operations. The switch isolates the configuration channel pin from the power bus pin when over-voltage is detected, preventing damage while maintaining ease of user operation without requiring careful unplugging techniques
Solution Approach 2:
The over-voltage detection circuit provides continuous feedback on voltage levels to the switch control mechanism. When the detected voltage exceeds the safe threshold, the feedback signal triggers the switch to isolate the pins, creating a closed-loop protection system that automatically responds to voltage conditions
Data Source
AI summary
An over-voltage protection circuit includes an over-voltage detection circuit, a voltage generator and a switch for providing over-voltage protection between two pins of a USB Type-C port. The over-voltage detection circuit provides an over-voltage signal according to the level of the second pin. The switch includes a first end coupled to the first pin, a second end coupled to the second pin and a control end coupled to a control signal. When the over-voltage signal does not indicate an over-voltage occurrence at the second pin, the voltage generator provides the control signal having a first level for operating the switch in a first region. When the over-voltage signal indicates an over-voltage occurrence at the second pin, the voltage generator adjusts the control signal to a second level for cutting off the switch. The switch operates in a second region after the over-voltage occurrence and before the switch is cut off.