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SoC boosts capacity in small form factor disk drives

Posted: 06 Oct 2005 ?? ?Print Version ?Bookmark and Share

Keywords:agere systems? nand flash? sc1200? truestore? soc?

SC1200 TrueStore CE storage SoC

Agere Systems' executives are pretty certain that high-density NAND flash device will not replace hard disk drives in laptops and media players. The company's latest device, the SC1200 TrueStore CE storage SoC, is directed at improving storage space in Small Form Factor (SFF) hard disk drives (HDD) and supports all of the HDD formats that exist, including 0.85-, 1- and 1.8-inch.

"What's really important in hard drive solutions is the storage capacity," said Duncan Furness, senior product manager for Agere's Storage Division. "There's a lot of discussion about flash vs. hard disk drives in handheld. They have to keep adding capacity to get the lowest price per gigabyte."

The SC1200 delivers three times the capacity over competing flash memory at lower cost-per-gigabyte, Furness said.

"This chip enables capacity in 1-inch hard drives of 12GB and greater. It's aimed at the sweet spot in terms of HDD capacity to maintain the lead in capacity over flash," he said.

Furness said that the company expects segmentation to occur in the marketplace, with low-cost applications dominated by NAND flash and the higher capacity-point devices, such as media players, employing HDDs.

According to Agere, consumer electronics represents the biggest opportunity for the disk drive sector. Video will drive the need for increased storage space in media players and mobile phones, he said.

And with perpendicular recording technology expected to bring significant capacity improvements in HDDs compared with longitudinal recording, the SC1200 storage SoC is designed to bring video and other high capacity files that require multiple gigabytes of storage to portable media products.

Perpendicular recording aligns bits vertically, perpendicular to the disk, and longitudinal recording aligns data bits horizontally, parallel to the surface of the disk. With longitudinal, magnetic bits on the drive platter have become so tiny, that they interfere with one another and corrupt data.

As new SFF drive designs incorporate perpendicular recording, Agere's chip offers a 0.5dB performance advantage over competing SoCs, translating to nearly 10 percent more capacity, the company said.

In addition to providing perpendicular recording support, the SC1200 SoC offers many host interface options, including consumer electronics CE-ATA and MMC plus industry standard pATA, CFII and PCMCIA.

"We've also put in more robust error correction code (ECC), 10-bit reverse encoding process, which offers a more effective signal-to-noise ratio, which means more capacity," he said.

The SC1200 is based on the ARM966ES architecture with a micro programmable disk sequencer. It employs the CopperHead ultra low power read channel with an embedded SRAM data buffer.

The SC1200 SoC is optimized for the TrueStore CE chipset, which includes the SC1200 SoC, as well as Agere's PA1100 preamplifer and MC1100 motor controller.

The SC1200 SoC integrates read channel, disk controller, memory, interface and other functions. It encodes and decodes data, manages data transfer between drive and host, and manages head position through servo logic.

The preamplifer is used to amplify minute analog signals before they are sent to a read channel IC for digitization. It also amplifies data from the read channel for the drive head to write on the platter.

The motor controller drives the spindle motor that spins the disk drive platters and maintains the spin rate. It moves the actuator to the correct track as instructed by the disk drive controller.

"Those three comprise all of the electronics in the HDD," Furness said. "If you do a comparison of chipset offerings against competitive solutions, [TrueStore] has the lowest component count, beating the competition by 20 components, lower cost, lower bill of materials, and fewer resistors and capacitors. The second benefit is you have a smaller outline for HDDs. HDDs are being asked to be thinner and thinner."

The entire chip set operates at 350-Mbits/s and features very low power consumption, extending battery life in handheld CE designs. The motor controller in the TrueStore CE chipset offers SmartPark technology for drive protection due to free fall, shock or power loss.

Furness also added that its latest chipset costs about a $1 less than competing solutions.

The SC1200 will be available in sample quantities for $10 each in early 2006. Agere's space-saving package and integration options include VTFS BGA packages, stacked or offset multi-chip modules, and 'package-less' bump-die configurations.

- Ismini Scouras

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