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Wireless Systems Design

Memory Solution Frees Up Storage Capacity

This Multi-Level-Cell, NAND-Based Internal Memory Device Confronts The Increasing Needs Of Mobile Devices.

In second-generation (2G) phones, memory is mainly used for voice. In some parts of the world, it is also used for SMS messaging. But 2G memory provides limited room for code storage and user storage capacity. Now, the onset of data services and the convergence of cellular phones and computing platforms are putting greater demands on memory. At the same time, wireless-systems engineers require any new memory to stay within cost, performance, reliability, capacity, and integration confines. To assuage these demands and simultaneously urge the industry forward, M-Systems, Toshiba America Electronic Components, Inc., and Toshiba Corp. have released the Mobile DiskOnChip G3.

The Mobile DiskOnChip G3 claims to be the world's smallest high-capacity NAND-based memory solution. The Flash disk is the first internal memory product based on M-Systems' x2 technology and multi-level cell (MLC) NAND Flash silicon (see figure). The MLC NAND, which hails from Toshiba, stores 2 b of data per cell instead of the 1-b-per-cell capacity that's typically found in single-level NAND flash. Basically, it thus doubles the storage capacity of the silicon.

M-Systems' x2 technology is comprised of a set of advanced proprietary algorithms designed to enable the Mobile DiskOnChip G3 product. By using a robust error-detection-code/error-correction-code (EDC/ECC) mechanism, the x2 technology overcomes MLC-related error patterns and slow transfer rates. For the Mobile DiskOnChip G3, the EDC/ECC mechanism translates into data integrity that is specifically tailored to MLC Flash technology.

For performance enhancement, the x2 technology offers multi-plane operations, direct-memory-access (DMA) support, and MultiBurst operation. It can therefore deliver a burst read speed of up to 80 MBps. This speed is crucial for features such as fast system boot and large file transfers of, for example, video and audio.

By relying on the x2 technology, the Mobile DiskOnChip G3 has enabled the first MLC NAND-based internal memory device. Toshiba's MLC NAND Flash can now be utilized within the Mobile DiskOnChip G3 family. The resulting device will offer sorely needed storage capacity to mobile handsets, PDAs, and other mobile wireless applications.

The Mobile DiskOnChip G3 garners attention for its capacity and size. As a complete nonvolatile-memory (NVM) solution, it features one silicon die containing 512 Mb (64 MB) of Toshiba's 0.13-µm MLC NAND Flash; an ultra-thin controller; and an execute-in-place (XIP) boot block. These parts are contained within a 7-×-10-mm BGA package.

The device also is highly cost effective. The trick was to use 0.13-µm MLC NAND instead of expensive legacy NOR Flash. The market may follow this step, as more individuals are starting to believe that the mobile-storage market should move away from NOR completely. But the choice to swap out NOR was just one step taken to optimize the Mobile DiskOnChip G3 for mobile applications. The companies also gave this device its deep power-down mode. When it's not in use, Mobile DiskOnChip G3 consumes as little as 10 µA to conserve battery life.

Samples of the 512-Mb Mobile Disk-OnChip G3 Flash disk will be available in the second quarter of 2003. Production is slated for the third quarter.

M-Systems, Inc.
8371 Central Ave., Suite A, Newark, CA 94560; (510) 494-2090, FAX: (510) 494-5545,

Toshiba Corp.
1-1, Shibaura 1-chome, Minato-ku, Tokyo 105-8001, Japan; +81-3-3457-4511, FAX: +81-3-3456-1631 or +81-3-3456-1632,

TAGS: Toshiba
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