Bidirectional MOSFET Protection Circuit for High-Voltage Isolation
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Solution Overview
Problem
Low-voltage electronic circuit components are vulnerable to failures and physical damage from excessive high voltages, and existing designs that limit maximum voltage are not always practical or feasible.
Innovation Solution
A bidirectional high-voltage protection circuit that includes a voltage sensing circuit and a control circuit to detect and respond to overvoltage conditions by creating a high-impedance path between the protected circuit and the high-voltage node, using switching networks and MOSFET devices to prevent damage from both positive and negative high voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing voltage limiting designs are used, then maximum voltage is limited to acceptable levels, but this approach is not always practical or feasible for certain applications
Solution Approach 1:
The patent introduces a protection circuit as an intermediary component between the high-voltage source and the low-voltage circuit components. This protection circuit includes voltage sensing circuitry that detects high-voltage conditions and control circuitry that activates switching networks (MOSFETs) to create protective paths, thereby mediating the interaction between high-voltage environments and voltage-sensitive components without limiting the overall system voltage capability
2Reliability
If protection circuits are added to detect and respond to overvoltage conditions, then component safety is improved, but circuit complexity increases
Solution Approach 1:
The patent combines multiple protection functions into a single integrated protection circuit block. The voltage sensing circuitry, control circuitry, and switching networks are merged into one cohesive unit that provides comprehensive overvoltage protection. This merging approach reduces the overall system complexity compared to using separate protection devices for each circuit component
Solution Approach 2:
The protection circuit is designed with universal functionality to handle both positive and negative high-voltage conditions through bidirectional switching networks. The same protection circuit can protect multiple low-voltage circuit components simultaneously, and the switching networks can operate in both directions to clamp both positive and negative voltage spikes, providing multi-functional protection with a single circuit design
Data Source
AI summary
Systems and methods herein use a sensing circuit to detect an overvoltage at a voltage node as a drain current. A current-mode comparator converts the detected current into a control signal, which is provided to a control circuit. The control circuit uses the control signal cut of a bias current to turn off switches in a protection circuit to create a high-impedance electrical path between the voltage node and the to-be-protected voltage node.