TLC Flash Data Writing Method for Power Loss Protection
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Solution Overview
Problem
Triple-level cell (TLC) flash memory devices face data loss issues due to the limitation of programming sequences, where incomplete programming of pages can result in unstable data that is not accurately readable after power interruption, leading to data loss when a shutdown command is issued.
Innovation Solution
A data writing method and solid state storage device that includes a controller, buffer, and flash memory, where redundant data is added to the buffer when a shutdown command is received, allowing multiple program procedures to ensure stable data storage by completing the programming of TLC cells before power loss, and re-generating redundant data upon power restoration to maintain data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple program procedures are performed to ensure stable data storage in TLC flash memory, then data reliability is improved, but programming time and device complexity increase
Solution Approach 1:
The patent applies preliminary action by detecting shutdown commands before they occur and proactively completing the programming sequence. The controller monitors host commands and identifies shutdown instructions, then finishes the remaining programming operations for affected pages before power is lost, ensuring data stability without requiring complex error correction mechanisms.
Solution Approach 2:
The patent implements feedback by continuously monitoring the programming status and host commands. The controller tracks which pages are being programmed and receives feedback from the host system about upcoming shutdown commands, allowing it to dynamically adjust the programming sequence to complete critical operations before power loss occurs.
2Reliability
If programming is interrupted during power loss, then data loss occurs, but continuing programming consumes additional time and energy
Solution Approach 1:
The system performs preliminary detection of shutdown commands and proactively completes programming operations before power is lost. By identifying the shutdown command in advance and finishing the programming sequence for affected pages, the system ensures data integrity without requiring time-consuming error detection and correction after power restoration.
Solution Approach 2:
The patent applies the skipping principle by rushing to complete the programming sequence for pages affected by shutdown commands. The controller prioritizes finishing these critical programming operations before power loss, skipping non-critical operations that can be deferred, thereby minimizing data loss risk while optimizing time consumption.
3Reliability
If redundant data is added to buffer to prevent data loss, then data recoverability is improved, but buffer usage and processing overhead increase
Solution Approach 1:
The patent applies preliminary action by detecting shutdown commands before they occur and proactively completing the programming sequence. The controller monitors host commands and identifies shutdown instructions, then finishes the remaining programming operations for affected pages before power is lost, ensuring data stability without requiring complex error correction mechanisms.
Solution Approach 2:
The system performs self-service by autonomously detecting shutdown commands and completing its own programming operations without external intervention. The controller independently monitors the programming status, identifies at-risk pages, and finishes their programming before power loss, eliminating the need for complex external error correction and data recovery mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method ensures that data stored in TLC flash memory remains stable and recoverable, preventing data loss during power interruptions and maintaining data integrity by completing the programming sequences and re-generating redundant data upon power restoration.
Implementation Method 1
During a program cycle of the flash memory, hot carriers are injected into the floating gate of the floating gate transistor. By controlling the amount of hot carriers to be injected into the floating gate, the threshold voltage of the floating gate transistor can be changed.
Implementation Method 2
During an erase cycle, the hot carriers are ejected from the floating gate of the floating gate transistor.
Data Source
AI summary
A data writing method for a solid state storage device includes following steps. A step (a) is performed to judge whether a shutdown command is issued from a host. In a step (b), if the solid state storage device confirms that the shutdown command is not issued from the host, plural program procedures are performed. Consequently, plural write data in a buffer are stored to a triple-level cell flash memory according to a program order. In a step (c), if the solid state storage device confirms that the shutdown command is issued from the host, plural redundant data are added to the plural write data, the write data are stored into the buffer, and the plural program procedures are performed. Consequently, the plural write data in the buffer are stored to the triple-level cell flash memory according to the program order.