NMOS Protection Switch Layout for Precise Overcurrent Detection
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Solution Overview
Problem
Existing electronic systems lack efficient and compact switches for protecting against overvoltage and overcurrent, with a need for improved detection precision and compatibility with the protected devices.
Innovation Solution
A switch comprising NMOS-type transistors configured in reverse ohmic mode, utilizing a combination of high and low voltage transistors to detect and respond to overvoltage and overcurrent, integrated with control circuits for precise detection and disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single high-voltage transistor is used for protection, then the device can handle overvoltage conditions, but the detection precision for overcurrent is insufficient
Solution Approach 1:
The patent divides the protection function into multiple specialized transistors: a first high-voltage transistor for handling overvoltage conditions and second low-voltage transistors for precise overcurrent detection. This segmentation allows each transistor to be optimized for its specific function, resolving the contradiction between overall protection capability and detection precision.
2Measurement precision
If multiple transistors are used to improve detection precision, then the detection capability is enhanced, but the device dimensions increase
Solution Approach 1:
The patent applies local quality by using low-voltage transistors with smaller dimensions specifically for the overcurrent detection function, while the high-voltage transistor handles the bulk protection function. This allows the device to achieve enhanced detection precision without a proportional increase in overall device volume.
3Adaptability or versatility
If high-voltage transistors are used for both protection and detection, then the protection range is expanded, but the compatibility with protected devices is reduced
Solution Approach 1:
The patent segments the transistor functions by using a high-voltage transistor for broad protection coverage and low-voltage transistors for precise detection compatible with sensitive electronic devices. This segmentation allows the system to maintain both wide protection range and high compatibility with protected devices.
4Volume of moving object
If a compact switch design is used, then the device dimensions are reduced, but the detection precision and protection capability are compromised
Solution Approach 1:
The patent uses low-voltage transistors with inherently smaller dimensions for detection functions, allowing compact overall device design while maintaining detection precision. The high-voltage transistor provides protection capability without requiring excessive space, as it operates in a different voltage regime with different dimensional requirements.
Data Source
AI summary
The present disclosure relates to a switch for protecting against overvoltage and overcurrent, comprising: a first NMOS-type transistor suitable for receiving across its conduction terminals a first voltage; a second NMOS-type transistor comprising a source terminal coupled to a source terminal of the first transistor, and being suitable for receiving across its conduction terminals a second voltage less than the first voltage; and a third NMOS-type transistor comprising a source terminal coupled to a source terminal of the first transistor, and being suitable for receiving across its conduction terminals the second voltage.