Flash Memory Controller Dynamic Read Threshold
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Solution Overview
Problem
The initialization process for downgrade flash memory is excessively time-consuming due to a high number of defective physical pages, leading to low productivity in manufacturing, as existing methods cannot efficiently test and identify usable capacity within a reasonable time frame.
Innovation Solution
A memory controller dynamically adjusts the read-operation threshold for each physical block during the initialization process, allowing the process to be completed within a set target time by sequentially selecting blocks and adjusting read-retry counts or page counts based on the number of defective pages encountered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the initialization process tests all physical pages in downgrade flash memory using conventional methods, then the usable capacity can be accurately determined, but the initialization time becomes excessively long
Solution Approach 1:
The patent applies dynamics by making the read-operation threshold adjustable during the initialization process. The threshold is dynamically modified based on the number of defective pages encountered, allowing the system to adapt the testing strictness in real-time. This resolves the contradiction by enabling accurate capacity determination when thresholds are high, while allowing faster initialization when thresholds are lowered based on actual defect rates.
Solution Approach 2:
The patent changes the parameter of read-operation threshold from a fixed value to a variable that can be adjusted during initialization. By modifying this parameter based on the ratio of defective pages found, the system can balance between thorough testing (for accuracy) and faster testing (for reduced time), thus resolving the technical contradiction between measurement precision and time loss.
2Measurement precision
If the read-operation threshold is set high to ensure accurate detection of defective pages, then the usable capacity determination is precise, but the initialization process exceeds the target time
Solution Approach 1:
The system dynamically adjusts the read-operation threshold based on the actual defect rate encountered during initialization. When many defective pages are found, the threshold is lowered to speed up the process; when fewer defects are found, the threshold remains high for accuracy. This dynamic adjustment resolves the contradiction between detection accuracy and initialization throughput.
Solution Approach 2:
The patent implements feedback by using the results of read operations (number of defective pages detected) to adjust the read-operation threshold for subsequent operations. This feedback mechanism allows the system to optimize the balance between detection accuracy and processing speed based on real-time conditions, thereby resolving the contradiction between measurement precision and productivity.
3Productivity
If the initialization process is accelerated to meet target time requirements, then productivity improves, but the accurate detection of defective pages may be compromised
Solution Approach 1:
The patent changes the read-operation threshold parameter dynamically to balance speed and reliability. By adjusting this parameter based on the defect rate encountered, the system can maintain reliable detection when thresholds are high while achieving faster initialization when thresholds are appropriately lowered, thus resolving the contradiction between productivity and reliability.
Solution Approach 2:
The system uses dynamic threshold adjustment to maintain detection reliability while improving initialization speed. The threshold is modified in real-time based on actual performance data, ensuring that reliability is not compromised even when acceleration is applied to meet target time requirements.
Data Source
AI summary
A memory controller is provided. The memory controller is coupled to a flash memory that includes a plurality of physical blocks, and each physical block includes a plurality of physical pages, and some of the physical pages are defective physical pages. The memory controller includes a processor that is configured to set a total target initialization time for an initialization process of the flash memory. The processor sequentially selects a current physical block from among all the physical blocks to perform the initialization process, and it performs a read operation of the initialization process on the current physical block using a read-operation threshold. In response to the read operation of the current physical block being completed, the processor dynamically adjusts the read-operation threshold of the read operation of the physical blocks, so that the initialization process is completed within the total target initialization time.