Overvoltage Detection Circuit for Serial Interface Transient Suppression
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Solution Overview
Problem
Impedance mismatches between the transmitter and receiver in serial interfaces, such as USB, cause overvoltage transients that can damage low-voltage circuit components in electronic devices, leading to potential failures.
Innovation Solution
An overvoltage detection circuit generates an enable signal when the voltage exceeds a threshold, activating a switch and an AC clipper circuit to clamp the output voltage, preventing damage from overvoltage transients by maintaining it at a tolerable level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If impedance matching is not performed in serial interfaces, then device complexity is reduced, but overvoltage transients occur causing damage to low-voltage circuit components
Solution Approach 1:
The patent introduces an intermediary protection circuit between the serial interface input and the low-voltage circuit components. This circuit includes a detection circuit that monitors voltage levels and a clamping circuit that activates to limit overvoltage transients, thereby protecting downstream components without requiring impedance matching modifications to the original interface
Solution Approach 2:
The protection circuit performs preliminary detection of voltage levels before overvoltage transients can reach vulnerable components. The detection circuit continuously monitors the input voltage and prepares the clamping mechanism in advance, so when an overvoltage event occurs, the protection is already positioned to immediately clamp the voltage to safe levels
2Reliability
If overvoltage protection circuits are added to serial interfaces, then reliability of low-voltage circuitry is improved, but device complexity increases
Solution Approach 1:
The protection circuit is designed to be self-regulating and automatic. The detection circuit autonomously monitors voltage conditions and triggers the clamping mechanism without requiring external control or intervention. The circuit serves itself by using the overvoltage condition as both the trigger and the parameter to be controlled, eliminating the need for additional control logic or complex coordination circuits
Solution Approach 2:
The patent combines the voltage detection function and the clamping protection function into a single integrated protection circuit module. The detection circuit and clamping circuit are closely coupled, sharing common signal paths and control nodes, which reduces the overall complexity compared to having separate independent protection systems
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
The solution effectively suppresses overvoltage transients, reducing the likelihood of device failures by ensuring the output signal is clamped to a safe level, thereby protecting low-voltage circuitry.
Implementation Method 1
activating a switch and an AC clipper circuit to clamp the output voltage, preventing damage from overvoltage transients by maintaining it at a tolerable level
Data Source
AI summary
An apparatus includes a transistor coupled between an input pin and an output pin and an overvoltage detection circuit configured to receive a serial interface signal from the input pin and generate an enable signal in response to a voltage of the serial interface signal exceeding a voltage threshold. The apparatus also includes a first circuit configured to apply a clamping voltage to a gate of the transistor based on the enable signal to regulate a voltage provided at the output pin.