Solid State Drive Self-Refresh Power Saving Mode

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Solution Overview

Problem

Existing storage devices face challenges in reducing power consumption during low-power modes without compromising data integrity and device performance, particularly in mobile systems that frequently switch between operational modes.

Innovation Solution

The implementation of a storage device with a non-volatile memory, a volatile memory that supports both normal and self-refresh modes, and a controller that manages transitions between these modes, allowing for efficient power-saving by deactivating most circuitry and using self-refresh mode in DRAM to minimize power consumption, while ensuring fast wake-up and reduced wear on non-volatile memory cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the storage device enters a low-power mode by deactivating most circuitry, then power consumption is reduced, but data integrity and device performance may be compromised

Engineering Contradiction:

Improvepower consumptionVSAvoiddata integrity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent segments the memory system into two distinct parts: volatile memory (DRAM) that enters self-refresh mode to retain data with minimal power, and non-volatile memory that serves as a backup. This segmentation allows the system to achieve low power consumption while maintaining data integrity through the dual-memory architecture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The controller performs preliminary actions by copying data from volatile memory to non-volatile memory before the storage device enters low-power mode. This advance preparation ensures that data is safely preserved in the non-volatile memory, guaranteeing data integrity when the device wakes up without requiring full data verification.

Inventive Principle:

Principle #10Preliminary action

2Speed

If the storage device uses volatile memory in normal mode for fast access, then device performance is improved, but power consumption increases

Engineering Contradiction:

Improvedata access speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic operation of the volatile memory, allowing it to switch between full operational mode (normal mode) for fast data access and low-power mode (self-refresh mode) for data retention. This dynamic state change enables the system to optimize between speed and power consumption based on operational requirements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

In self-refresh mode, the volatile memory performs periodic refresh operations to maintain data integrity while consuming minimal power. This periodic action allows the memory to retain data without continuous full-power operation, achieving a balance between data availability and power savings during low-power states.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If the storage device frequently switches between operational modes, then adaptability is improved, but wear on non-volatile memory cells increases

Engineering Contradiction:

Improvemode switching capabilityVSAvoidmemory cell lifespan

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The patent employs non-volatile memory as a disposable backup layer that can withstand repeated write operations. By using this more durable memory type for periodic data preservation during mode transitions, the system enables frequent adaptability switches while the robust non-volatile memory absorbs the wear from repeated data copying operations.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Use of energy by moving object

If the storage device deactivates the primary interface to save power, then power consumption is reduced, but the device cannot respond to wake-up commands

Engineering Contradiction:

Improvepower consumptionVSAvoidwake-up capability

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The patent extracts the wake-up functionality from the primary interface by implementing a separate, dedicated wake-up interface. This extracted interface remains active with minimal power consumption while the primary interface is deactivated, allowing the device to maintain wake-up capability without the power cost of keeping the full primary interface operational.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The separate wake-up interface acts as an intermediary that bridges the host and the storage device during low-power states. This intermediary channel enables wake-up commands to be transmitted without requiring the primary interface to be active, solving the contradiction between power savings and operational responsiveness.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9568971B2Solid state drive with self-refresh power saving mode

Publication Date: 2017.02.14 APPLE INC

AI summary

A storage device includes a non-volatile memory, a volatile memory and a controller. The volatile memory supports a normal mode and a self-refresh mode. The controller is configured to store data for a host in the non-volatile memory while using the volatile memory in the normal mode and, in response to receiving a power-down command from the host, to deactivate at least part of the storage device and to switch the volatile memory from the normal mode to the self-refresh mode.