Flash Memory Controller Bad Column Skip Logic
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Solution Overview
Problem
Flash memory devices often have inaccessible columns due to manufacturing defects, leading to inefficiencies in data storage and retrieval operations.
Innovation Solution
A data storage device with a controller that skips bad columns by utilizing a bad column data set, which includes a starting address and the number of columns to skip, during read and write operations, allowing for efficient navigation around defective columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the controller sequentially accesses all columns from first column to Nth column during read or write operations, then the data access process is simple to implement, but the operational efficiency deteriorates due to time-consuming skips over bad columns
Solution Approach 1:
The patent pre-calculates and stores bad column data sets in a lookup table during manufacturing or initialization. These data sets contain starting addresses and column counts for bad column ranges. During normal read/write operations, the controller simply queries this pre-prepared data to determine which columns to skip, avoiding the need for complex real-time defect detection and enabling efficient batch skipping of multiple consecutive bad columns.
2Loss of time
If the controller skips individual bad columns one by one, then the implementation is straightforward, but the time consumption increases significantly when multiple consecutive columns are bad
Solution Approach 1:
The patent merges multiple individual bad column entries into consolidated bad column data sets that represent continuous ranges of bad columns. Each data set contains a starting address and a count of consecutive bad columns. This merging approach allows the controller to skip multiple consecutive bad columns in a single operation rather than processing them individually, significantly reducing the time required when multiple adjacent columns are defective.
3Reliability
If the system maintains detailed records of all bad columns, then the data integrity is ensured, but the memory space requirements increase
Solution Approach 1:
The patent changes the representation parameters of bad column data from individual column addresses to range-based parameters (starting address and column count). This parameter transformation compresses the data structure by representing multiple consecutive bad columns with just two values instead of multiple individual addresses, significantly reducing the memory space required to maintain reliable records of bad columns while preserving complete information about defective regions.
Data Source
AI summary
A data storage device including a flash memory and a controller. The flash memory includes a plurality of dies having a plurality of columns, wherein each of the columns is constituted by a plurality of sectors. The controller performs a read operation or a write operation from a first column to an Nth column in response to a read command or a write command, and skips at least two columns within the range of the first column to the Nth column according to a first bad column data set, wherein the first bad column data set has a starting address and the number of columns.