Memory Programming Recovery After Sudden Power-Off
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Solution Overview
Problem
Memory systems face challenges in accurately resuming program operations after sudden power-offs due to unpredictable power loss, leading to potential data loss and reduced reliability.
Innovation Solution
A memory system and method that includes a memory device with latches to store code values and a controller to manage suspend and recovery commands, restoring changed code values to original states using threshold voltage comparisons during power recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the memory device changes the code value to an erase code value in response to a verification pass during programming, then the programming operation can be completed efficiently, but the original code value is lost and cannot be recovered if power is suddenly interrupted
Solution Approach 1:
The memory device performs preliminary actions by storing the original code value in a backup location (first latch) before changing it to the erase code value. This preliminary preservation allows the original value to be recovered if needed, resolving the contradiction between efficient programming (changing code value) and data integrity (preserving original value).
Solution Approach 2:
The system discards the original code value from the primary storage location after verification, but recovers it from the backup latch when a sudden power-off is detected. This discarding and recovering mechanism enables both efficient programming operations and reliable data recovery after power interruptions.
2Reliability
If the memory device suspends programming operation in response to detecting a sudden power-off, then data integrity can be preserved, but the programming operation cannot be completed and requires recovery operations
Solution Approach 1:
Before suspending the programming operation upon detecting sudden power-off, the system performs preliminary actions by preserving the original code value in the backup latch. This preliminary preservation enables reliable data integrity while setting up the conditions for future recovery operations.
Solution Approach 2:
The system uses feedback from the sudden power-off detection to trigger the recovery operation. The feedback mechanism monitors the programming state and power status, and when power interruption is detected, it activates the recovery process that restores the code value from the backup latch, ensuring both reliability and eventual productivity recovery.
3Reliability
If the memory device stores the original code value in latches during programming, then the code value can be recovered after sudden power-off, but additional storage resources are consumed
Solution Approach 1:
The system applies local quality by implementing backup storage only for the code value portion that needs recovery, rather than duplicating the entire memory cell data. The first latch specifically stores the original code value while the memory cells retain their programmed state, providing targeted redundancy that balances reliability with device complexity.
Solution Approach 2:
The system discards the original code value from primary storage after successful verification, transferring it to a compact backup latch. This allows recovery capability with minimal additional storage resources, as the backup latch only needs to hold the code value temporarily until recovery is complete or power is restored.
Data Source
AI summary
Provided herein are a memory system and a method of programming the same. The memory system may include a memory device including memory cells for storing data and a plurality of latches for storing code values indicating the data. The memory device may be configured to program data into each of the memory cells, store an original code value indicating the data in the plurality of latches, and change the original code value stored in the plurality of latches to an erase code value in response to a verification pass, and a memory controller configured to output, to the memory device, a suspend command for suspending at least the programming in response to detecting a sudden power-off and a recovery command for restoring a code value changed to the erase code value.