Interface Switching Circuit Control for USB Over-Voltage Pulses
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Solution Overview
Problem
Conventional USB interface circuits face issues where a small voltage pulse can mistakenly turn off the switching circuit, causing signal interruptions and risking damage to internal low voltage components, while extending reaction time increases the risk of back-end component damage.
Innovation Solution
An interface circuit comprising a switching circuit, an over-voltage detection circuit, and a control signal generating circuit that selectively adjusts the gate voltages of transistors in the switching circuit to prevent immediate shutdown due to small voltage pulses, allowing continued signal transmission while protecting against high voltage levels by gradually reducing the control signal voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching circuit is turned off quickly to protect internal low voltage components, then over-voltage protection effectiveness is improved, but the switching circuit becomes easily interfered with by noise and may be turned off by mistake
Solution Approach 1:
The patent implements dynamic response characteristics by configuring the switching circuit to exhibit different response behaviors for different types of voltage disturbances. Temporary shutdowns are prevented for voltage pulses below a threshold duration, while sustained over-voltage conditions trigger permanent shutdown. This dynamic differentiation allows the system to respond appropriately to both noise and genuine over-voltage threats.
Solution Approach 2:
The patent changes the parameter of switching response time based on the characteristics of the detected voltage signal. By monitoring the duration and magnitude of voltage pulses, the system adjusts its response threshold - ignoring short-duration pulses that fall below the temporary shutdown threshold while responding to sustained over-voltage conditions. This parameter-based differentiation resolves the contradiction between quick response and noise immunity.
2Object-affected harmful factors
If the reaction time of the over-voltage protection circuit is extended to reduce noise interference, then noise immunity is improved, but the risk of back-end low voltage component damage increases
Solution Approach 1:
The patent segments the protection response into two distinct modes: temporary shutdown for short-duration voltage pulses and permanent shutdown for sustained over-voltage conditions. This segmentation allows the system to extend reaction time for brief noise events while maintaining quick protection for genuine threats. The dual-mode approach divides the protection function into time-based categories, resolving the contradiction between extended reaction time and component protection.
Solution Approach 2:
The system dynamically adjusts its protection strategy based on the temporal characteristics of the detected voltage signal. By implementing a time-based differentiation mechanism, the circuit extends its effective reaction time for noise filtering while maintaining rapid response capability for sustained over-voltage conditions. This dynamic time-based approach allows simultaneous achievement of noise immunity and component protection.
3Reliability
If the switching circuit is turned off by a small voltage pulse to protect internal circuits, then protection response is improved, but signal transmission is interrupted causing abnormal operations
Solution Approach 1:
The patent changes the response parameter from immediate shutdown to time-based differentiation. By introducing a temporary shutdown threshold based on pulse duration, the system maintains protection response capability while avoiding unnecessary interruptions of normal signal transmission. Short-duration pulses below the threshold are ignored, preserving signal continuity, while sustained over-voltage conditions still trigger appropriate protection.
Solution Approach 2:
The system implements feedback monitoring of voltage pulse characteristics to determine appropriate response actions. By continuously monitoring the duration and magnitude of voltage pulses and comparing them against threshold values, the circuit provides intelligent feedback-based control. This feedback mechanism ensures protection responses are triggered only when genuinely necessary, maintaining signal transmission continuity while preserving protection capability.
Data Source
AI summary
The present invention provides an interface circuit, wherein the interface circuit includes a switching circuit, an over-voltage detection circuit and a control signal generating circuit. In the operations of the interface circuit, the switching circuit is configured to receive an input signal from an input terminal, and selectively transmit the input signal to an internal circuit. The over-voltage detection circuit is configured to detect whether a voltage level of the input signal is greater than a threshold value, and accordingly generate at least one over-voltage signal. The control signal generating circuit is configured to generate a control signal according to said at least one over-voltage signal, to control the switching circuit to be in one of three or more states.