Overvoltage Protection Circuit with Rectifier-Controlled Parallel Switching
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Solution Overview
Problem
Conventional surge protection circuits for semiconductor integrated circuits often fail to effectively draw surge current into the VSS terminal in a timely manner, leading to potential destruction of internal circuits due to variations in the breakdown time of MOS transistors.
Innovation Solution
An overvoltage protection circuit is designed with a rectifier and multiple stages of switching elements connected in parallel, where the rectifier outputs a control voltage to turn on the switching elements, ensuring that overcurrent is drawn into the VSS terminal, thereby protecting the internal circuit from abnormal overvoltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If MOS transistors are used as switching elements, then the circuit structure is simple, but the breakdown time variation prevents timely surge current diversion
Solution Approach 1:
A rectifier and control voltage generation circuit are introduced as intermediary components. When overvoltage occurs, the rectifier generates a control voltage that simultaneously triggers all MOS transistors to turn on. This intermediary mechanism ensures timely and synchronized operation of the switching elements, solving the speed problem while maintaining the simplicity of using MOS transistors.
2Reliability
If a conventional surge protection circuit is used, then the internal circuit can be protected from overvoltage, but the surge current may not be drawn into VSS terminal in time due to transistor breakdown variation
Solution Approach 1:
The rectifier continuously monitors the voltage at the input terminal and provides feedback control. When overvoltage is detected, it generates a control voltage that triggers the MOS transistors to turn on. This feedback mechanism ensures that the protection function is activated at the precise moment when overvoltage occurs, eliminating the time loss caused by variations in transistor breakdown timing.
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 allows for the successful and timely diversion of surge current into the VSS terminal, effectively preventing damage to the internal circuit by ensuring that the switching elements turn on sequentially to distribute the surge current across the entire area, enhancing the protection and layout flexibility of the semiconductor integrated circuit.
Implementation Method 1
a rectifier which has an input end connected to the first terminal, and an output end; and first-stage to n-th-stage switching elements respectively having first to n-th controlling ends to which an output voltage from an output end of the rectifier is applied
Data Source
AI summary
Disclosed is an overvoltage protection circuit which includes a first terminal through which a first voltage is supplied to an internal circuit; a second terminal through which a second voltage is supplied; a rectifier having an input end connected to the first terminal and having an output end; and first-stage to n-th-stage switching elements which are connected in parallel to one another. The first-stage to n-th-stage switching elements have first to n-th controlling ends, respectively. Each of the switching elements has first and second controlled ends connected to the first terminal and the second terminal, respectively. The rectifier is configured to output a control voltage from the output end thereby to cause the first-stage to n-th-stage switching elements to be turned on, in response to receipt of an overvoltage from the first terminal.