TORONTO – Two different memory vendors are using different approaches to address the demand for faster smartphones with more storage capacity.
In time for this year’s Mobile World Congress, SanDisk unveiled its iNAND 7132, which includes its iNAND Accelerator and its new SmartSLC technology using the e.MMC 5.0+ HS400 specification. The new iNAND component consists of X3 TLC NAND die, a controller, and firmware, with capacities available up to 64GB.
iNAND 7132 is intended to support high-performance applications such as professional grade digital photography and 4K Ultra HD video playback, said Rafael Feitelberg, senior director of strategic marketing for SanDisk Mobile and Connected Solutions. When SanDisk looked at MLC sequential write performance in its iNAND 7030 and TLC sequential write performance in its iNAND 5130, he said the company found the majority of applications don’t place stress on storage performance. (Those that do include burst photography.)
In the iNAND 7132, the X3 NAND cells can be formatted as both TLC and SLC, with the SLC areas having much higher write speeds. With SmartSLC, some of the overprovisioned areas of the flash are formatted as SLC, said Feitelberg. The logic in the controller and the firmware monitor the requests of the host, and the firmware detects when the host needs high performance, allowing the device to control whether data is written to the smart SLC or to the main array, he explained. The iNAND Accelerator uses SmartSLC for burst performance.
While SanDisk is using TLC with e.MMC for its iNAND 7132, Samsung has opted to use the Universal Flash Storage (UFS) 2.0 standard with MLC NAND in its new 128GB embedded memory. The JEDEC-compliant, UFS memory is double that of the company’s current e.MMC offerings.
David Ghodsizadeh, Samsung Semiconductor’s associate product marketing manager for NAND Flash, said the company has been working closely with its ecosystem partners and that UFS is well-suited for the high-end smartphone market, with e.MMC continuing to be used in mid- to low-end smartphones for the foreseeable future. And while TLC is being adopted in high-end smartphones, he expects continued use of MLC in these devices.
Moving to UFS 2.0 made sense, added Hank Lai, Samsung Semiconductor’s senior manager of memory product planning, because the controller technology for UFS is more mature this year, and with high-end smartphones doing intensive computing, they require SSD-like performance, which UFS 2.0 can support.
Lai said, in the future, Samsung’s UFS memory could take advantage of the company’s recently announced ePoP packaging, whereby the new UFS memory could be stacked directly on top of a logic chip, and reduce the overall space required.
Research firm Gartner expects to see increased adoption of TLC in high-end smartphones, said Brady Wang, principal research analyst at Gartner, in an email interview with EE Times. With its use in the iPhone 6, TLC has shown itself to be viable due to the quality of the controller. Originally, the read/write speed of TLC-based smartphones was slower than MLC-based smartphones, he said. However, with a good controller, TLC can achieve the same or even better performance than MLC.
Prior to the iPhone 6, said Wang, TLC NAND was limited to use in low-cost smart phones, due to both performance and reliability concerns. But with users generally switching to new phones within two years, the reliability of TLC has proven good enough within that product life cycle.
Wang doesn’t believe UFS will replace e.MMC soon given that the cost of UFS is still higher. UFS does offer better performance, higher capacity, better bandwidth, better IOPS, and optimized performance for multi-threaded applications, he said, but it also consumes more power than e.MMC, which will constrain its adoption, although the energy efficiency of UFS is better than e.MMC. Right now, UFS is best suited for ultrabooks or tablets which have high capacity batteries and smartphones that require high performance.
Jim Handy, principal analyst with Objective Analysis, said the primary benefits of UFS is that is supports much faster communication rates and larger data sizes. “This is really good if you’re downloading huge files onto to your cellphone, such as a feature film.” The speed of UFS also makes backing up a smartphone much faster, he said. “Any time you are moving a lot of data, UFS is always an advantage.”
The UFS specification is falling into place, said Handy, but it’s still relatively new. “Samsung is a key proponent and someone has to take the first step. It behooves them to be the first one to do it.”