Flash Memory Controller Dummy Read Operations

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Solution Overview

Problem

3D flash memory designs face data reading quality issues due to data deterioration when blocks are not read for long periods, leading to decoding difficulties or inability to read data correctly.

Innovation Solution

A flash memory controller that performs a dummy read operation on blocks using a timer-generated time information, independent of host device commands, to prevent data deterioration by periodically accessing and refreshing data in unread blocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If 3D flash memory design is used to increase capacity, then storage capacity is improved, but data reading quality deteriorates due to data deterioration in unread blocks

Engineering Contradiction:

Improvestorage capacityVSAvoiddata reading quality

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The controller performs dummy read operations on blocks that have not been read for a predetermined period before actual data reading is needed. This preliminary action refreshes the data in blocks that are likely to be accessed soon, preventing data deterioration and ensuring reliable reading when the host actually requests the data.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller periodically performs dummy read operations on blocks based on time information from a timer. By periodically accessing blocks that haven't been read recently, the system maintains data integrity in 3D flash memory without requiring continuous monitoring or intervention.

Inventive Principle:

Principle #19Periodic action

2Reliability

If dummy read operations are performed periodically on all blocks, then data reading quality is improved, but device complexity and power consumption increase

Engineering Contradiction:

Improvedata reading qualityVSAvoidcontroller complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of uniformly applying dummy read operations to all blocks, the controller selectively performs dummy reads only on blocks that meet specific criteria (not read for a predetermined period). This localized approach focuses resources on blocks that actually need refreshing, reducing unnecessary operations and simplifying the overall system design.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system uses its own timer and block management information to automatically identify which blocks need dummy read operations. The controller monitors its own block access patterns and autonomously decides when to perform dummy reads, eliminating the need for external monitoring systems or complex coordination mechanisms.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11487655B2Method for managing flash memory module and associated flash memory controller and electronic device based on timing of dummy read operations

Publication Date: 2022.11.01 SILICON MOTION INC

AI summary

The present invention provides a flash memory controller, wherein the flash memory controller is arranged to access a flash memory module, and the flash memory controller includes a ROM, a microprocessor and a timer. The ROM stores a program code, the microprocessor is configured to execute the program code to control the access of the flash memory module, and the timer is used to generate time information. In the operations of the flash memory controller, the microprocessor refers to the time information to perform dummy read operations upon at least a portion of the blocks, wherein the dummy read operations are not triggered by read commands from a host device.