Agere's 1394 silicon simplifies upgrade

Agere Systems Inc. is seeding the PC market with a combination of 1394 silicon that could offer board makers greater flexibility in migrating from the 400Mbps version of the standard to the less popular, 800Mbit version.

By the end of 2006, more than five million PCs will have shipped with 1394b, but that's still just a fraction of the market. By far, the lower-cost 480Mbps USB2.0 spec has dominated, even against 1394a, and especially in power-sensitive notebooks. But as applications typically used by high-end desktop PC users, such as editing and storage of uncompressed video, trickle down to the mainstream, demand should increase for high-capacity external Serial ATA drives that use 1394b.

With that pending transition in mind, Agere is promoting a "pop" option, short for populate. PC board makers will be able to match the FW430—a 1394a physical-layer/link—with an optional external 1394b PHY called the FW843. Both have three ports and run on a PCI bus. "This will keep our customers from having to carry the cost of 1394b on motherboards that aren't really going to use it. It also helps to keep them from having two different motherboard designs for 1394a and 1394b," said Dan Devine, USB and 1394 product line manager at Agere.

Until now, the 1394b market has mostly been dominated by one company, Texas Instruments Inc., which last month said it was moving more aggressively into enabling 1394b in the notebook PC space with an open host-controller interface that stacks link and physical-layer communications chips onto one 7-by-7mm package.

Agere has been providing 1394b link-layer chips for about three years, and the introduction of the PHY should spice up the competition in the PCI and CardBus space.

Another boost will come when Microsoft Corp. integrates native support for 1394b into its forthcoming Vista operating system. Currently, in Windows XP, when users slot in CardBus adapters for 1394b, the OS throttles back the data rate to 1394a's 400Mbps.

The FW430 comes in a 7-by-7mm package and runs on a 3.3V power supply. The FW843 comes in an 84-pin 10-by-10 MLCC package, and runs on 1.8-, 3.3- and 5V supplies. It requires an external 24.5MHz crystal to drive the internal phase-locked loop.

Agere will also roll a USB 2.0-based modem this week that it says will save 80 percent of the space used for routing traces in older PCI modems. The SV92U2 will come in three flavors: an internal modem that directly replaces the PCI modem, an external USB dongle and a minicard.

- Mike Clendenin
EE Times