Non-Volatile Memory Refresh Triggering After Vehicle Power-Down
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Solution Overview
Problem
Non-volatile memory devices experience unreliable data storage and retention when programmed at extreme temperatures, particularly affecting multi-level cells, leading to read failures and data loss due to varying operating characteristics across temperature changes.
Innovation Solution
A host system monitors environmental inputs to trigger a refresh operation on non-volatile memory after the system powers down, ensuring memory cells programmed at extreme temperatures are refreshed as the temperature stabilizes, using a host system controller to manage refresh commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-volatile memory is programmed at extreme temperatures, then data storage capacity is achieved, but data retention reliability deteriorates
Solution Approach 1:
The system performs a refresh operation on non-volatile memory blocks before they are programmed at extreme temperatures. This preliminary action prepares the memory cells by stabilizing their electrical characteristics, ensuring that subsequent programming at extreme temperatures does not compromise data retention reliability
Solution Approach 2:
The system changes the temperature parameter by waiting for extreme temperatures to subside before programming memory. It monitors temperature conditions and only proceeds with programming when temperatures return to normal ranges, thereby avoiding the reliability degradation caused by extreme temperature programming
2Reliability
If refresh operations are performed continuously, then data retention is improved, but energy consumption increases
Solution Approach 1:
Instead of continuous refresh operations, the system implements periodic refresh operations triggered by specific conditions. It performs refresh operations only when temperature thresholds are exceeded or before programming operations at extreme temperatures, rather than continuously refreshing all memory blocks, thereby reducing energy consumption while maintaining data retention
Solution Approach 2:
The system uses the host system controller to autonomously monitor temperature conditions and trigger refresh operations only when necessary. This self-service approach allows the memory system to manage its own refresh needs based on actual environmental conditions, avoiding unnecessary energy consumption from routine refresh operations
3Quantity of substance
If multi-level cells are used to increase storage density, then storage capacity is improved, but read failure rate increases at extreme temperatures
Solution Approach 1:
The system performs preliminary refresh operations on multi-level cell blocks before programming them at extreme temperatures. This preliminary action stabilizes the memory cells' electrical characteristics, ensuring that the delicate threshold voltage distributions of multi-level cells are not distorted by extreme temperature conditions during programming
Solution Approach 2:
The system changes the operational parameter by avoiding programming of multi-level cells at extreme temperatures. It monitors temperature conditions and only programs multi-level cell blocks when temperatures are within acceptable ranges, thereby preventing read failures while maintaining high storage density
Data Source
AI summary
Methods, systems, and devices for triggering a refresh for non-volatile memory are described. A host system may communicate with a memory system, where the host system and memory system may be included within a vehicle (e.g., an automotive system). The host system may receive an indication that the vehicle is powering down and may enter a power off state in response to the indication. The host system may detect a trigger (e.g., using a time or temperature input) to switch back to a power on state while the vehicle is powered down, the trigger associated with performing a refresh operation at the memory system. The host system may enter the power on state and may transmit a power on command to the memory system. The memory system may perform the refresh operation on one or more memory cells while the vehicle remains in the powered down state.