NAND Flash Overview

NAND flash rapidly changes in technology nodes and number of bits per cell, ever increasing the user capacity while constantly reducing the cost per bit.
The main differentiator of NAND flash is the number of bits per cell.

· SLC (single level cell) stores 1 bit per cell
· MLC (multiple level cell) stores 2 bits per cell
· TLC (triple level cell) stores 3 bits per cell
· QLC (quadruple level cell) stores 4 bits per cell

The reliability and retention of each programmed level shrinks with each additional bit.
Swissbit continues to ship products with SLC, MLC, and 3D NAND TLC technology.

3D NAND Technology

3D NAND is the dominant technology to increase chip capacity and reduce cost without stretching the limits of lithography.
The high integration was possible by turning from Floating Gate as a storage element to Charge Trap Layer. This allows an easy vertical rotation of the bit lines and currently stacking of more than 100 layers.

The new 3D NAND enables high density products at lower cost, but requires significantly higher error correction and sophisticated flash firmware management. Only few 3D NAND products are able to fully support an industrial temperature grade of -40°C to +85°C and in particular a cross temperature of 125°K which indicates the allowed temperature change between write and read access.
While lots of 3D NAND products are available in consumer quality, only few products truly support industrial 3D NAND.
Swissbit uses high quality and industrial grade TLC NAND technology for most of the newly introduced products.

 

 

 

 

NAND Flash Comparison

The endurance of flash-based products is primarily defined by the maximum number of program/erase cycles of the flash components. SLC components normally allow 100,000 PE cycles per block, while MLC and 3D TLC are typically specified with 3,000 PE cycles. Nevertheless, other factors like retention, long-term availability, temperature range and cost per bit differ significantly with the technology, as can be seen from the table.

Controller Features

The controller and firmware used in Swissbit products differ significantly from consumer products. The Swissbit controller balance performance with low power consumption, offer high error correction capability and support of industrial temperature grade.
The Firmware features optimization for retention, endurance, protection against data loss at sudden power fail, and strong error correction.

Data care management Data Care Management

Various effects like data retention, read disturb limits, or temperature can affect data reliability. The latest generation of Swissbit products use special methods to maintain and refresh the data for higher data integrity.

Data Care Management

Power Fail Protection & Recovery Power fail protection

Intelligent Firmware Power Fail Protection & Recovery protects data from unexpected power loss. After an unintentional shutdown, firmware journaling ensures that all stored system and user data will be recovered correctly and no data is lost.

Power fail protection

Read-only optimized Read-only optimized

In many industrial applications, the data is written to the NAND Flash once and is only read afterwards. For such cases, the firmware can be optimized in order to guarantee highest possible data retention and less read disturb.

Read-only optimized

Secure erase Secure erase (Sanitize / Purge) / Fast erase

This feature uses an uninterruptable sequence of data erase commands. Even a power off cannot stop the process, which will continue upon restoration of power. The optional enhanced feature allows the customer to sanitize the data according to different standards like DoD, NSA, IREC, etc. The purge algorithm can be started by a software command or through a hardware pin.

Secure erase (Sanitize / Purge) / Fast erase

Temperature sensor Temperature sensor

The sensor allows the host hardware or software to monitor the memory device temperature to improve data reliability in the target application environment.

Temperature sensor

TRIM support Trim support

The TRIM command allows the operating system to inform the SSD, which blocks of data are no longer considered in use and can be wiped out internally, which increases system performance in following write accesses. With TRIM Support data scrap can be deleted in advance, which otherwise would slow down future write operations to the involved blocks.

Trim support

Write Amplification Factor WAF reduction

The WAF (write amplification factor) for MLC-based products is reduced by combining a paged based FW block management with a powerful card architecture and configuration settings.

WAF reduction

Wear leveling Wear leveling

Sophisticated Wear Leveling & Bad Block Management ensure that Flash cells are sparingly and equally used in order to prolong lifetime of the device.

Wear leveling

End 2 End Data Path Protection

E2E DP adds parity protection or error correction to the internal data path and RAM / ROM arrays of the Flash controller. This prevents unrecognized corruption of data.

End 2 End Data Path Protection

Block RAID

RAID (Redundant Array of Inexpensive Disks) technology is used on NAND block level to repair a complete page fail. This provides additional protection against 3D NAND related fails.

Block RAID

NAND Features

The NAND devices that Swissbit uses must fulfill stringent requirements as high quality, wide temperature range, long availability

High quality

Swissbit uses NAND products with highest quality grade in order to provide products with lowest DPPM rates and highest reliability

High quality

Longevity Longevity

The longevity product lines use special components with a long-term supply commitment of up to 10 years. These products offer lowest TCO in demanding applications with high requalification cost.

Longevity

Wide temperature support Wide temperature support

Swissbit‘s embedded memory & storage solutions are designed and approved for reliable operation over a wide temperature range. The products are verified at temperature corners and prestressed with a burn-in operating functional test (Test During Burn In – TDBI).

Wide temperature support

SSD Features

Swissbit products incorporate a rugged design, shock and vibration resistance, and support for lifetime monitoring

Electrostatic discharge and electromagnetic interference ESD and EMI safe

The product designs are in line with the latest regulations for electrostatic discharge and electromagnetic interference. Swissbit strives to exceed these limits with our own in-house technology and production capabilities, for example with System-in-Package (SiP) competence.

ESD and EMI safe

Life Time Monitoring (LTM) Lifetime monitoring (LTM)

The Swissbit Lifetime Monitoring feature enables users to access the memory device’s detailed Lifetime Status and allows prediction of imminent failure, avoiding unexpected data loss. This feature uses an extended S.M.A.R.T. (Self-Monitoring, Analysis and Reporting Technology) interface or vendor-specific commands to retrieve the Flash product information.

Lifetime monitoring (LTM)

Shock & Vibration Shock and vibration

Robustness is one of our key specification targets. The design, assembly, and use of selected materials guarantee an extremely solid design, which has been validated by extensive testing.

Shock and vibration

Temperature sensor Temperature sensor

The sensor allows the host hardware or software to monitor the memory device temperature to improve data reliability in the target application environment.

Temperature sensor

Wide temperature support Wide temperature support

Swissbit‘s embedded memory & storage solutions are designed and approved for reliable operation over a wide temperature range. The products are verified at temperature corners and prestressed with a burn-in operating functional test (Test During Burn In – TDBI).

Wide temperature support

Hardware Power Fail Protection

Products with the Swissbit powersafe feature use reliable tantalum capacitors to store energy so that in case of a sudden power fail the charge will be used to harden the cache content into the NAND flash.

Hardware Power Fail Protection

Conformal coating Conformal Coating

Swissbit offers a special protective coating on selected products. This coating is a thin polyurethane film, which protects against aggressive environmental conditions such as dust, moisture, or corrosive gas.

Conformal Coating