NAND Memory Controller Power Loss Data Retention

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

During programming operations in memory devices, sudden power losses can lead to data loss and programming errors, and the use of capacitors to mitigate this issue consumes significant energy and increases manufacturing costs.

Innovation Solution

A method for retaining inflight data during power loss events involves suspending programming operations, identifying an erased page address, providing inflight data to a buffer, programming the data to the erased page using existing programming voltage without ramping down the programming pump, and relocating the data upon power restoration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If capacitors are used to provide supplemental power during programming operations, then data loss is prevented, but energy consumption increases and manufacturing cost increases

Engineering Contradiction:

Improvedata retention during power lossVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts the supplemental capacitor from the power loss protection system and replaces it with the existing programming pump voltage. The programming pump, which already generates high voltage for programming operations, is repurposed to maintain voltage during power loss events, eliminating the need for separate energy storage capacitors and reducing overall energy consumption.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The programming pump is given a dual function: it not only performs the standard programming voltage generation but also serves as the power loss protection mechanism. By maintaining the programming pump operation during power loss events, the system uses the same component for both programming and data retention, eliminating the need for dedicated protection capacitors.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If larger capacitors are used in enterprise systems with multiple NAND dies, then data retention during power loss is improved, but manufacturing cost increases

Engineering Contradiction:

Improvedata retention during power lossVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent removes the expensive supplemental capacitor component from enterprise systems with multiple NAND dies. Instead of adding larger capacitors to protect multiple dies, the system repurposes the existing programming pump infrastructure to provide protection, significantly reducing component count and manufacturing cost.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The programming pump serves itself by providing power loss protection through its own operational voltage. The system uses its existing programming infrastructure to protect its own data, eliminating the need for external protection components and reducing manufacturing complexity.

Inventive Principle:

Principle #25Self-service

3Use of energy by moving object

If programming pump voltage is maintained during power loss events, then energy consumption is reduced, but data retention capability must be sufficient

Engineering Contradiction:

Improveenergy consumptionVSAvoiddata retention during power loss

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent prepares the programming pump in advance by keeping it operational before power loss occurs. The pump is already generating the necessary voltage for programming when power is lost, so no additional voltage generation or capacitor charging is needed during the event. This preliminary preparation ensures immediate data protection while minimizing energy consumption.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The programming pump continues its voltage generation operation continuously through the power loss event without interruption. By maintaining the pump's useful action of voltage generation, the system provides uninterrupted power for data retention without the energy waste of charging and discharging capacitors.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS12205658B2Systems and methods for retaining inflight data during a power loss event

Publication Date: 2025.01.21 SANDISK TECHNOLOGIES LLC

AI summary

Memory devices, or memory systems, described herein may include a controller (e.g., SSD controller) and a NAND memory device for storing inflight data. When the power loss event occurs, a memory system maintains (i.e., not un-select) the existing memory block being programmed at the time of power loss. The existing program operation at the event of power loss can be suspended by controller. The inflight data can be re-sent by controller directly to NAND latches, when power loss event was detected. The memory system can select a next, immediate available erased page and begin one-pulse programming to store the inflight data, without ramping down the program pump and program pulse, which was in use before the power loss event. The existing programming voltage is used to store/program the inflight data via single pulse programming. When power is restored, the inflight data is moved/programmed to another block for good data reliability.