eFUSE Switch Circuit Layout for Backflow Blocking in Hard Drives
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Solution Overview
Problem
Conventional switch devices with a fuse function face challenges in preventing backflow currents due to the configuration of body diodes, which requires additional components and increased layout size, especially when handling high voltages.
Innovation Solution
A switch element with integrated body diodes connected in opposite directions, along with a configuration where the first switch is connected to ground potential instead of the drain, allowing for reduced layout size and efficient anti-backflow functionality without the need for high-withstand voltage elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional switch devices use body diodes to prevent backflow currents, then backflow prevention is achieved, but layout size increases and additional components are required
Solution Approach 1:
The patent combines the backflow prevention function with the existing body diodes of the switch element. By configuring the body diodes to be connected in opposite directions between the back gate and source/drain, the switch element itself provides bidirectional backflow protection without requiring separate external diodes or additional components, thereby reducing layout size while maintaining reliability
Solution Approach 2:
The switch element is designed to perform multiple functions: switching operation, overcurrent protection (eFUSE function), and backflow prevention. The body diodes serve dual purposes as inherent components of the switch element structure and as backflow protection elements, eliminating the need for dedicated backflow prevention components
2Reliability
If additional components are added for backflow prevention, then backflow currents are blocked, but device complexity increases
Solution Approach 1:
The patent merges the backflow prevention function into the switch element's existing structure by utilizing its body diodes. This integration eliminates the need for separate backflow prevention components, reducing device complexity while maintaining the required reliability for backflow protection
3Strength
If high-withstand voltage elements are used for backflow prevention, then high voltage handling is achieved, but layout size and device complexity increase
Solution Approach 1:
The switch element serves as a multi-functional component that provides both switching operation and backflow prevention. The body diodes, which are inherent to the switch element structure, provide backflow protection without requiring separate high-withstand voltage elements, thereby maintaining voltage handling capability while reducing layout size and device complexity
Data Source
AI summary
The present disclosure provides a switch device. The switch device includes: a switch element, including a gate, a drain, a source, a back gate, a first body diode disposed between the drain and the back gate and a second body diode disposed between the source and the back gate; a first switch circuit, including a first switch connected between the back gate and an application end at ground potential; and a second switch circuit, including a second switch connected between the back gate and the source.