Fuse Blow Detection Circuit for Partially Blown Fuse Identification
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Solution Overview
Problem
Existing fuse testing methods in integrated circuits cannot reliably detect partially blown fuses, which can lead to improper selection of redundant memory sections, resulting in storage errors due to the appearance of fully blown fuses.
Innovation Solution
A fuse blow detection circuit and method that includes a fuse circuit with a pre-charge circuit, inverter, feedback latch, and test circuit, allowing for the differentiation between fully blown, partially blown, and intact fuses by adjusting the strength of the feedback latch in normal and test modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional fuse testing methods are used, then the testing process is simple, but partially blown fuses cannot be detected and appear as fully blown fuses
Solution Approach 1:
The feedback latch strength is dynamically adjusted between normal mode and test mode. In test mode, the latch strength is reduced to enable detection of partially blown fuses that would otherwise be indistinguishable from fully blown fuses using traditional static testing methods.
Solution Approach 2:
The pre-charge circuit pre-charges the common node to a predetermined voltage level before the actual fuse testing occurs. This preliminary action prepares the circuit in a known state, enabling accurate detection of fuse conditions by establishing a reference point for comparison.
2Reliability
If a partially blown fuse is not detected, then the memory array can be accessed normally, but storage errors occur due to improper section selection
Solution Approach 1:
The feedback latch continuously monitors the voltage level at the common node and adjusts its state based on the fuse condition. This feedback mechanism enables reliable detection of partially blown fuses by comparing the actual voltage against expected thresholds, preventing improper memory section selection.
Solution Approach 2:
The testing circuit changes the operational parameters of the feedback latch by adjusting its strength between normal and test modes. This parameter change enables the circuit to detect subtle voltage differences caused by partially blown fuses that would be invisible under normal operating conditions.
3Stability of the object's composition
If the feedback latch strength is increased for normal operation, then the common node is maintained at HIGH level reliably, but partially blown fuses cannot be detected
Solution Approach 1:
The feedback latch strength is dynamically adjusted between normal mode (stronger latch for stability) and test mode (weaker latch for detection sensitivity). This dynamic adjustment allows the circuit to maintain stable operation during normal use while enabling precise detection of partially blown fuses during testing.
Data Source
AI summary
System and method for testing the reliability of a fuse blow condition. The fuse blow detection circuit includes a fuse circuit comprising a fuse having a first end coupled to ground. A common node is coupled to the second end of the fuse. A pre-charge circuit is coupled to the common node for pre-charging the common node to a pre-charged HIGH level. An inverter includes an inverter output and an inverter input, wherein the inverter input is coupled to the common node. A feedback latch is coupled between a voltage source and ground, and includes a latch input that is coupled to the inverter output and a latch output coupled to the common node. A test circuit is included that is coupled to the common node, wherein in a normal mode the test circuit adds strength to the feedback latch for purposes of maintaining the common node at the pre-charged HIGH level, such that in a test mode the feedback latch is weaker than in the normal mode for purposes of maintaining the common node at the pre-charged HIGH level.