Fuse Circuit Isolation Against Accidental Programming
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Solution Overview
Problem
Integrated circuits with fuses are prone to accidental programming due to power supply transients and electrical overstressing, leading to unintended changes in fuse resistance, which can result in defective semiconductor dies during manufacturing and field implementation.
Innovation Solution
A fuse circuit design that includes multiple switches and biasing circuits to control current flow through the fuse, along with protective elements like capacitors and diodes, to prevent accidental programming by isolating the fuse from undesired voltage spikes and transient events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fuses are used to store information in integrated circuits, then manufacturing precision and unique code storage are improved, but susceptibility to accidental programming due to power supply transients and electrical overstressing increases
Solution Approach 1:
The fuse programming path is segmented into multiple series-connected switches (first switch and second switch) rather than using a single switch. This segmentation ensures that both switches must be simultaneously turned on by a genuine programming signal to program the fuse, while accidental transients or overstress events are unlikely to activate both switches simultaneously, thus preventing accidental programming.
Solution Approach 2:
The first and second switches act as intermediary protective elements between the fuse and the power supply/transient events. These switches control and mediate the current flow through the fuse, allowing legitimate programming signals to pass through while blocking harmful transient currents and electrical overstress, thereby protecting the fuse from accidental programming.
2Reliability
If multiple switches and biasing circuits are added to protect against accidental programming, then reliability is improved, but device complexity increases
Solution Approach 1:
The first switch and second switch are merged into a single series connection path with the fuse, and their control logic is integrated through shared biasing circuits. This merging approach achieves enhanced protection reliability while minimizing the increase in device complexity by using a compact series architecture rather than parallel or distributed protection structures.
Solution Approach 2:
The biasing circuits serve multiple functions: they control the switching states of both the first and second switches, provide protection against accidental programming, and enable legitimate fuse programming when required. This multi-functionality reduces the need for separate dedicated protection circuits, thereby limiting the increase in device complexity while maintaining high reliability.
Data Source
AI summary
Circuits, methods, and devices for protecting against accidental fuse programming are discussed herein. For example, a fuse circuit may include a fuse, a first switch coupled to a first point and coupled in series with the fuse, and a second switch coupled in series with the fuse between the fuse and a second point.