Fat NAND controllers to slim down
NAND controllers to lose die-dependent functions
Micron says some flash controller jobs are going to migrate down stack towards the NAND chips, freeing up controller manufacturers from chip-dependent work they shouldn't be doing.
It sees low-level flash controllers developing and taking on error management, taking this job away from existing NAND controllers.
Micron takes the view that today's NAND controllers carry out both die-specific and application-specific functions. They should only carry out application-specific functions and leave the die-specific stuff to the flash fab owners. Micron's Kevin Kilbuck, a strategic marketing director, says error correction and checking (ECC) and broader error management functions are die-specific whereas block management and wear-levelling are application dependent. How these are carried out on USB, tablet and enterprise storage array flash, for example, are very different, hence Micron's strategy.
Kilbuck says the benefit is that controller development can carry on without being hog-tied to specific NAND die technology implementations.
Micron is not interested in developing general NAND controllers and taking on SandForce, Pliant and other controller technology companies. Instead it sees a way to add value to its flash dies with its ClearNAND technology. Kilbuck anticipates similar products from Micron's flash fab competitors: "We know we're not alone."
Kilbuck says ClearNAND is an ASIC that sits between a NAND controller and the flash dies. It is not an IMTF (Intel Micron Flash Technologies) product, only a Micron product, and has a raw NAND-like interface from both directions: the NAND dies below and the NAND controller above.
Micron will add digital signal processing technology to its ClearNAND in future, seeing this as die-dependent. It thus poses a threat to Anobit, which is developing a line of controllers, using DSP to extend SSD endurance.
By 2014, Micron sees the flash market split between raw NAND, part-managed ClearNAND type product, and fully-managed NAND, which may well be seen in mobile phones. Micron has an eMMC controller, which provides fully-managed NAND for such devices. ®