Flash Memory Refresh Register Control for Data Retention
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Solution Overview
Problem
Flash memory experiences issues such as read disturb, program disturb, charge loss, and bit-flip errors due to lack of standardized data refresh mechanisms, leading to data integrity problems and varying refresh operations across different consuming devices.
Innovation Solution
Implementing standard registers in Flash memory for controlling refresh operations, allowing a host device to set parameters like start/stop, target partitions, address ranges, and refresh algorithms, ensuring consistent and optimized data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operations are performed frequently to correct bit-flip errors, then data retention is improved, but performance of the Flash memory is degraded
Solution Approach 1:
The patent implements periodic refresh operations at predetermined intervals rather than continuous or on-demand refreshing. The memory controller monitors elapsed time and triggers refresh operations based on predetermined time thresholds, allowing normal read/write operations to proceed uninterrupted until a refresh is scheduled. This periodic approach maintains data retention while minimizing performance impact by limiting refresh interruptions.
Solution Approach 2:
The patent performs refresh operations before data is lost by proactively monitoring time elapsed since last refresh and triggering refresh operations based on predetermined time intervals. This preliminary action prevents bit-flip errors from compromising data integrity, while the predetermined timing ensures refresh occurs before performance-critical operations are impacted.
2Reliability
If vendor-specific refresh mechanisms are used, then data retention can be maintained, but consistency across different consuming devices is lost
Solution Approach 1:
The patent implements a universal refresh mechanism that can be applied across all consuming devices regardless of vendor or application type. The memory controller uses standardized parameters (predetermined time intervals, block identification, refresh triggering) that can be uniformly implemented across different devices and applications, ensuring consistent data retention behavior while maintaining adaptability to various Flash memory configurations.
3Extent of automation
If internal refresh control is used, then refresh operations can be performed autonomously, but lack of information on retention requirements leads to suboptimal refresh timing
Solution Approach 1:
The patent implements a feedback mechanism where the memory controller continuously monitors the elapsed time since the last refresh operation and compares it against predetermined time intervals. Based on this feedback, the controller dynamically triggers refresh operations at optimal times. This closed-loop approach ensures autonomous operation while maintaining optimal refresh timing adapted to actual device usage patterns and retention requirements.
Data Source
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AI summary
A method of performing refresh operations on a flash memory, the method comprising: accessing, by a host device, a flash memory for controlling read or write operations of the flash memory, the flash memory comprising one or more refresh registers, wherein refresh operations performed on the flash memory are based on values in the one or more refresh registers, the one or more refresh registers comprising at least one of: a first register, a second register, a fourth register, or a fifth register; and performing, by the host device, operations for: setting the first register to start the refresh operations of the flash memory and clearing the first register to stop the refresh operations; programming the second register to indicate at least one partition of one or more target memory partitions of the flash memory for the refresh operations; programming the fourth register to indicate a refresh algorithm for performing the refresh operations; or reading the fifth register indicating a refresh rate of the flash memory.