Dynamic Thermal Region Tag Allocation for Stable Sense Voltage
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Solution Overview
Problem
Existing storage devices assign thermal region tags (TRTs) based on current programming temperatures, leading to inconsistent sense voltage application across meta blocks programmed at different times, increasing the risk of read failures due to varying programming conditions.
Innovation Solution
A storage device controller dynamically allocates TRTs to meta blocks based on current temperature, time since TRT assignment, temperature fluctuations, and the number of blocks assigned to a TRT, updating TRT parameters to ensure optimal sense voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If TRTs are assigned based solely on current programming temperature, then the TRT assignment process is simple, but read failures increase due to varying programming conditions over time
Solution Approach 1:
The patent makes the TRT assignment dynamic by introducing time-based validity periods and allowing TRT parameters to be updated periodically. Instead of static temperature-based assignment, the system now dynamically evaluates current temperature, time since last assignment, and temperature fluctuations to determine whether to reuse existing TRTs or allocate new ones, adapting to changing programming conditions over time.
Solution Approach 2:
The patent changes multiple parameters including temperature thresholds, time validity periods, and temperature fluctuation limits. By monitoring changes in these parameters over time and comparing them against predefined thresholds, the system determines whether existing TRTs remain valid or need to be updated/reallocated, thereby adapting to varying programming conditions without increasing operational complexity.
2Measurement precision
If TRT parameters are updated frequently to account for changing conditions, then read accuracy improves, but system overhead increases
Solution Approach 1:
The patent implements periodic action by establishing validity periods for TRT assignments and scheduling periodic evaluations of temperature and time conditions. Instead of continuous monitoring and updates, the system checks whether the current time exceeds the validity period or whether temperature fluctuations have exceeded thresholds at periodic intervals, reducing management overhead while maintaining adequate precision.
Solution Approach 2:
The system uses feedback mechanisms by monitoring temperature fluctuations and time elapsed since last TRT assignment, comparing these against predefined thresholds, and only updating TRT parameters when necessary. This feedback-based approach avoids unnecessary updates while ensuring accuracy is maintained when conditions actually change, balancing precision with reduced overhead.
Data Source
AI summary
A storage device allocates a thermal region tag (TRT) to a meta block based on a programming temperature and other conditions that may affect an optimal TRT parameter. A controller in the storage device programs a meta block and obtains a current temperature, a first TRT associated with the current temperature, and a parameter associated with the first TRT when closing the meta block. The controller determines that the first TRT has been active for more than a predefined active period, a temperature fluctuation across a predefined number of thermal regions occurred during previous meta blocks programming, and/or a number of meta blocks assigned to the first TRT is greater than a TRT compaction threshold. The controller deactivates the first TRT, allocates a second TRT to a thermal region including the current temperature, and assigns the second TRT to the meta block.