Non-volatile Memory Power-Down Data Protection

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Solution Overview

Problem

Non-volatile memory devices, particularly multi-level cell (MLC) devices, face data loss or corruption due to electrical power interruptions during Most Significant Bit (MSB) storage operations, which can also affect Least Significant Bit (LSB) data, leading to undesirable corruption of previously written data.

Innovation Solution

Implementing an alternative storage operation that detects imminent power interruptions and switches to a faster storage mode, either by backing up data to an alternative location or modifying programming levels to ensure LSB data integrity, allowing for recovery and minimizing data loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a second type of storage command is used to store second data in analog memory cells, then data storage capability is improved, but power-down time increases and data corruption risk increases during power interruptions

Engineering Contradiction:

Improvedata storage capabilityVSAvoidpower-down time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by detecting imminent power interruptions during the second storage operation and switching to a first faster storage operation before power is lost. This preliminary detection and switching mechanism ensures that critical data can be saved quickly before power interruption occurs, resolving the contradiction between enhanced storage capability and increased power-down time vulnerability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically switches between different storage operations based on detected power interruption conditions. When power stability is confirmed, the slower second storage operation is used for optimal data storage. When power interruption is detected, the system transitions to the faster first storage operation, creating a dynamic adaptation that resolves the time vulnerability contradiction

Inventive Principle:

Principle #15Dynamics

2Quantity of substance

If a second type of storage command is used to store second data in analog memory cells, then data storage capability is improved, but data integrity deteriorates during power interruptions

Engineering Contradiction:

Improvedata storage capabilityVSAvoiddata integrity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent performs preliminary detection of power interruption conditions during the second storage operation and triggers a switch to the first storage operation before power is lost. This preliminary action prevents data corruption by ensuring critical data is stored using the more interruption-resistant first operation, thereby maintaining data integrity while preserving the enhanced storage capability of the second operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system prepares for potential power interruptions by having a fallback first storage operation ready. When power instability is detected, the system switches to this pre-prepared alternative operation that is more resistant to power interruptions, providing a cushioning effect that protects data integrity while maintaining the ability to use the more capable second operation under normal conditions

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If a faster storage operation is used to protect data from power interruptions, then data protection is improved, but storage speed advantage is lost

Engineering Contradiction:

Improvedata protectionVSAvoidstorage speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The system dynamically selects between storage operations based on real-time power condition monitoring. Under normal stable power conditions, the faster second storage operation is used to maximize storage speed. When power interruption is detected, the system switches to the more protective first storage operation, creating a dynamic system that achieves both speed advantage and data protection at different times rather than sacrificing speed permanently

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent essentially creates a copy protection mechanism where critical data is stored using the faster first operation as a protective copy when power interruptions are detected. This copying approach allows the system to maintain the primary fast second storage operation for normal use while creating protective copies using the more interruption-resistant first operation when needed, preserving overall storage speed while improving protection

Inventive Principle:

Principle #26Copying

Data Source

PatentUS9672919B2Techniques for reducing power-down time in non-volatile memory devices

Publication Date: 2017.06.06 APPLE INC

AI summary

A method includes, in a memory including analog memory cells, storing first data in a group of the memory cells using a first type of storage command that writes respective analog values to the memory cells in the group. Second data is stored in the memory cells in the group, in addition to the first data, using a second type of storage command that modifies the respective analog values of the memory cells in the group. Upon detecting imminent interruption of electrical power to the memory during storage of the second data, a switch is made to perform an alternative storage operation that is faster than the second type of storage command and protects at least the first data from the interruption.