USB-bridge controller supports multilevel-cell NAND flash
By Maury Wright, Editorial Director, EDN Worldwide -- EDN, December 13, 2007
Last year, Cypress Semiconductor announced the West Bridge family of chips that primarily add high-speed-USB support to products such as mobile handsets. Full-speed transfers between handset memory and the USB interface, with no assistance from the handset application processor, have proved to be the primary benefit of West Bridge. Now, Cypress is launching the Astoria flavor of West Bridge, adding an MLC (multilevel-cell)-NAND-flash-memory controller.
Cypress claims that MLC flash costs a third of single-level-cell flash for the same storage capacity, making MLC support attractive in applications ranging from handsets to media players to digital cameras. Many of the standard storage modules, such as USB-memory sticks or SD (secure digital) cards use MLC memory but integrate the controller, thereby hiding the complexity of the control function. But designers who wish to embed MLC flash have little choice when it comes to the control function.
Astoria can control 16 MLC NAND memories and supports devices from all of the major flash vendors. The controller includes bad-block management, static-wear-leveling support, and 4-bit ECC (error-correction circuitry). You can interface Astoria to all popular processors and DSPs. And, like its predecessor, the chip supports 16 USB endpoints and a host of programmable-I/O features. The IC sells for less than $5 (500,000).
