Delkin Blog

Read Disturb 101

When choosing memory for applications, one consideration engineers weigh is the number of read and write operations that are expected. In some cases, applications have very few write cycles. For example, in gaming, it is usually only necessary for software to be loaded onto the memory card, and then only read operations are required when end users play the game. Although the absence of write operations means there are fewer demands on storage, read disturb errors are still possible. As such, it’s necessary for engineers to choose memory solutions that are optimized to reduce the likelihood of these read disturb problems.

 

Causes of Read Disturb Errors

Within NAND flash memory, read disturb errors generally happen for two reasons. One is a biasing condition that happens during read operations. The cells in NAND memory are strung together in a line that is similar to a multi-input NAND gate. When a read operation is initiated, the appropriate word line is biased to the read threshold voltage. The word lines not involved in the read operation are biased to high voltage simultaneously. This allows the selected cells’ state to move to the sense amplifier by creating a fully conducting NAND string. A side effect of biasing is the programming of the unselected word lines. As that same read cycle is performed repeatedly, the programming of the word lines will increase, ultimately triggering a sensing error.

 

Another common cause of read disturb errors is cross-coupling noise. Cross-coupling noise occurs in nearby cells, and it gets worse as usage of the memory device increases. Errors caused by cross-coupling noise also increase in high temperatures. As temperatures increase, charges to and from memory cells also increase.

 

Reducing the Risk of Read Disturb Errors

Just as there are two main causes of read disturb errors, there are two solutions that can be integrated into memory devices to reduce them. Devices can incorporate an ECC error detection capability that will trigger re-writes of important data any time a particular operational threshold is met.

 

Read wear leveling is another tool that can fight read disturb errors. Read wear leveling keeps track of read disturb errors per block of cells. When the count reaches a pre-determined number, the entire block of data is re-written to a different block, completely refreshing the block affected by the read disturb errors.

 

If you’re concerned about the impact of read disturb errors on your industrial application, discuss your needs with the product team at Delkin. We can provide custom storage solutions to meet your application’s requirements.

 

Contact

  • This field is for validation purposes and should be left unchanged.

Related Posts

Comparing Solid State Storage Companies

  Not all solid state storage companies are created equally. Although it can be tempting...

Delkin Devices and the Industrial Applications Market: Storage Solutions for Industrial Environments

  At Delkin, we serve a diverse industrial applications marketplace with wide-ranging storage needs. The...

Guide to Embedded Multimedia Card (eMMC)

  Embedded Multimedia Card (eMMC) General Description Designed for a wide range of applications in consumer...

Technical Success Stories: Delkin Matches Product & Testing to Unique Environmental Requirements

  CompactFlash as a form factor has been a stable, industrial, storage medium used by...

Managing Errors in NAND Flash Based Devices

    General In today’s systems, having a Nor flash (protected) bios supporting system boot from USB...

Embedded Computing
The Benefits of Using Industrial Flash Storage for Embedded Computing Applications

    Industrial grade flash storage devices have a higher endurance, a locked BOM, longer life...

Industrial IoT Applications Requiring Industrial Flash Storage

  Across the globe, many industries are on the crossover of revolution and many manufacturers...

Answering Common Questions about SMART SSDs

 SMART is a critical technology for SSDs, or solid-state drives. It makes locating the...

Medical Device Flash Storage: Factors to Consider

  Hospitals and other medical organizations have grown increasingly reliant on technology to deliver patient...

Digital Signage
Technical Success Story: Digital Signage Life Cycle Management

  Digital signage is a critical way of conveying information for a business or an...