Memory Controller Block Status Determination via Lock-Out Signal
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Solution Overview
Problem
Flash memory devices experience reliability issues due to unstable power supply voltages, leading to potential data loss and storage failures, as existing technologies fail to accurately differentiate between defective memory blocks and those affected by power fluctuations.
Innovation Solution
A memory controller method that determines memory blocks as either normal or bad based on a lock-out signal, allowing for the identification and reuse of blocks affected by power supply issues rather than labeling them as defective, thereby improving data reliability and storage efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory blocks are marked as bad when operation fails, then data reliability is improved by avoiding defective blocks, but power-related failures are misclassified as block defects causing unnecessary block marking and reduced storage capacity
Solution Approach 1:
The patent segments the failure analysis into two distinct parts: checking for lock-out signal first (power-related failure indicator), then determining block status. This segmentation allows differentiation between power-related failures and actual block defects, preventing misclassification of functional blocks as bad blocks.
Solution Approach 2:
The lock-out signal acts as an intermediary indicator that mediates between the operation failure and the block status determination. By introducing this intermediate check, the system can identify whether a failure is due to power supply issues (lock-out signal present) or actual block defects (no lock-out signal), thus avoiding unnecessary marking of functional blocks as bad.
2Reliability
If all operation failures are treated as block defects, then defective blocks are identified, but functional blocks affected by power fluctuations are incorrectly marked as bad reducing storage efficiency
Solution Approach 1:
The patent implements a dynamic determination process where the block status (normal or bad) is not fixed but depends on the state of the lock-out signal. This dynamic approach allows the system to adaptively classify blocks based on whether the failure is power-related or defect-related, optimizing storage efficiency by keeping functional blocks available.
Solution Approach 2:
The system changes the parameter used for block classification from a simple operation success/failure parameter to a more nuanced parameter set that includes the lock-out signal state. This parameter change enables differentiated treatment of failures, preserving storage efficiency by not marking power-affected blocks as bad.
3Reliability
If the system checks lock-out status information, then power-related failures are distinguished from block defects, but the complexity of the determination process increases
Solution Approach 1:
The patent applies preliminary action by checking the lock-out signal status before making the block status determination. This preliminary check provides crucial information about the nature of the failure, enabling more accurate classification without requiring complex analysis during the main determination process.
Solution Approach 2:
The lock-out signal serves as feedback information that informs the block status determination. By incorporating this feedback mechanism, the system can accurately differentiate between power-related failures and block defects, improving reliability while maintaining a relatively simple determination process through clear feedback-based decision logic.
Data Source
AI summary
An operating method of a memory controller to control a nonvolatile memory device includes receiving information about operation failure from the nonvolatile memory device, receiving lock-out status information from the nonvolatile memory device, determining whether a lock-out signal is output based on the lock-out status information, and determining a failure block corresponding to the information about the operation failure as a normal block or a bad block depending on the determination result.