Memory Device Refresh End Signal Reduces Idle Time
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Solution Overview
Problem
Memory devices experience idle time during refresh operations due to the lack of a clear indication of completion, leading to inefficiencies in subsequent operations.
Innovation Solution
A memory system that includes a memory device capable of generating a refresh end signal before the refresh operation is completed, allowing the memory controller to receive this signal and initiate subsequent commands only after confirmation of completion, thereby reducing idle time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the memory controller waits for the predetermined tRFC time before issuing subsequent commands, then the refresh operation is ensured to be completed, but the memory device stays idle causing time loss
Solution Approach 1:
The memory device generates a refresh end signal (REF_DONE) that provides feedback to the memory controller indicating when the refresh operation is actually completed. This feedback mechanism allows the memory controller to adjust its command timing based on real completion status rather than relying on conservative predetermined time estimates, thereby eliminating idle time while ensuring refresh completion.
Solution Approach 2:
The memory device autonomously monitors and determines its own refresh operation completion status by generating the REF_DONE signal based on internal operation timing. This self-service approach eliminates the need for the memory controller to conservatively wait for predetermined time periods, as the memory device itself provides accurate completion information.
2Loss of time
If the memory controller issues subsequent commands immediately after refresh command, then idle time is reduced, but the refresh operation may be interrupted causing data loss
Solution Approach 1:
The REF_DONE signal provides real-time feedback to the memory controller about refresh operation status. The memory controller uses this feedback to make informed decisions about when to issue subsequent commands, ensuring that refresh operations complete without interruption while minimizing idle time. The feedback creates a reliable synchronization mechanism between refresh execution and command issuance.
3Reliability
If the memory controller uses predetermined tRFC time for command timing, then refresh completion is guaranteed, but operational efficiency is reduced due to conservative timing
Solution Approach 1:
The refresh end signal provides accurate completion feedback that replaces conservative predetermined timing estimates. This enables the memory controller to optimize command timing based on actual refresh duration, improving operational efficiency while maintaining reliability through real-time status information.
Solution Approach 2:
The system transitions from static predetermined timing (fixed tRFC values) to dynamic timing based on actual refresh completion status. The memory controller adapts its command timing dynamically using the REF_DONE signal, allowing optimal performance while ensuring refresh completion without relying on conservative fixed time margins.
Data Source
AI summary
A memory system includes: a memory device suitable for performing a refresh operation in response to a refresh command, and for providing a refresh end signal where the refresh end signal is enabled before the refresh operation is completed; and a memory controller suitable for transferring the refresh command to the memory device and receiving the refresh end signal.