Thunderbolt not yet feasible for smartphones and tablets, Intel says

Power issues mean its use will be restricted for now to personal computers and possibly some tablet/PC hybrids

The Thunderbolt interconnect technology could take a while to reach smartphones and tablets because of power consumption issues that need to be resolved, Intel executives said on Wednesday.

Intel would like to bring Thunderbolt to portable gadgets but there are tradeoffs that have to be made when using the technology in low-power devices, said Jason Ziller, director of Thunderbolt planning and marketing at Intel, after a presentation at the Intel Developer Forum in San Francisco.

Thunderbolt might instead find its way into hybrid ultrabooks based on Core processors, on which screens can be detached to become tablets, Ziller said. The tablet/PC hybrids draw more power and are more appropriate to handle the high data transfer rates of 10Gbps (bits per second) provided by the high-speed interconnect.

Thunderbolt transfers data at high speeds between devices and external peripherals. Intel initially envisioned the technology as something that would be used across both personal computers and mobile devices, but it is currently found in Apple's Mac and Windows PCs from Lenovo, Acer, Asus and Hewlett-Packard. The technology supports PCI-Express 2.0 and DisplayPort technologies.

Intel's focus right now is squarely to ensure Thunderbolt works well on the Windows and Mac OS platforms. Intel officials could not provide a timeline for when the technology could reach mobile devices.

The technology was co-developed by Intel and Apple and officially launched early last year. There are currently 37 peripherals available for Thunderbolt-equipped Macs, including external storage devices and an Apple display. Intel has said it hopes to have 100 peripherals with Thunderbolt by the end of the year.

Thunderbolt cables are currently based on copper and can transfer about 10 watts of power. A sub 2-watt mobile device may not be designed to handle the current implementation of Thunderbolt, said Jeff Hockert, an engineer at Intel.

The power specification calls for 10 watts, but due to a power drop Intel is officially prescribing 8.5 watts over the cables. Intel is also eyeing a new interconnect for 2015 using silicon photonics that can transfer data at 50Gbps.

Intel hopes to boost data transfer rates on Thunderbolt in the future via support for PCI-Express 3.0.

Intel also said that optical cables will become an available option for Thunderbolt in the fourth quarter. The cables will be able to extend up to 30 meters but will not carry power, which means peripherals might need to be connected to power outlets. The copper cables are just a few meters long but can carry power over that shorter distance.

Sumitomo is shipping test samples of 20-meter-long optical cables.

A "second generation" of Thunderbolt copper cables will also be available at lower prices, Intel said. A 25 percent reduction in production cost has helped bring down the price, Hockert said.

An alternative to Thunderbolt is USB 3.0, which the USB Implementers Forum this week said will reach handhelds and smartphones by the end of this year.

Agam Shah covers PCs, tablets, servers, chips and semiconductors for IDG News Service. Follow Agam on Twitter at @agamsh. Agam's e-mail address is

Copyright © 2012 IDG Communications, Inc.

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