Cellphones warm up to magnetic coupling

SAN JOSE, Calif. — Magnetic coupling has been around for years, but 2009 may be the year cellphones adopt the technology, giving wireless power a toehold in a mass market.

At the Consumer Electronics Show, Palm Inc. showed magnetic induction built into its Palm Pre which is expected to ship by midyear. Vendors say a handful of other handset makers are designing wireless charging capabilities into their cellphones this year.

Several component vendors are angling to help them do it, using a variety of approaches. Two of them have started a standards effort in hopes they could attract a broader set of design wins.

The Pre is the first of many cellphones that will build in magnetic couple by next year's CES, said Jim Schuessler, senior technical marketing manager for portable products at National Semiconductor. “I know of several major companies designing it in, but we see this as a long adoption cycle on the order of 5-10 years,” he said.

Interest in wireless power has been slowly building, according to Mitch Randall, chief technology officer and founder of WildCharge, a Boulder, Colo.-based startup using a conduction technique that it first showed at CES in 2007

“The first year it was really new to everyone, a curiosity,” he said. “Last year there was tremendous interest, but it had the flavor of 'why would I want it and how can I make money from it?' Now I'm getting the impression people are ready to do it and want to figure out which approach to use,” Randall said.

The trend to wireless power has come and gone before, taking with it a handful of startups. But those involved say the momentum now feels real.

Several factors are driving interest, said Schuessler. Smartphone makers increasingly need something to differentiate their products. In addition, users need to charge the devices more frequently because batteries are not growing in size or capability as fast as handsets are packing in new power-sucking features.

“A phone in 2002 had standby power of three or four days, but today you are lucky if it lasts full day, so people are looking for more convenient ways to charge them,” he said.

Growing environmental concerns are also a factor. “If this trend is successful there will be a diminishing need for a charger in ever box,” he said, decreasing the growth in electronic waste in so-called wall warts often left plugged in and sucking unneeded energy.

The components needed are relatively simple. A metallic coil embedded in a plugged in base station links to ones embedded in a handset, digital camera or other device. They typically need a rectifier, some filters and a basic microcontroller to supervise the charging regime, leading to a total bill of materials of perhaps $10 per device.

“We know it has to go lower than that, and we see a road map to get to much lower costs with integration on both sides of the link, but that won't happen unless there is a larger market,” said Schuessler, indicating an all-too-familiar chicken-and-egg game in electronics.

Although most of the components are based on off-the-shelf chips, National ultimately plans to roll out patented synchronous rectifiers that could raise efficiency and lower heat for wireless charging systems. “We believe with our intellectual property we have a leg up,” he said.

At least half a dozen companies are offering different approaches to magnetic coupling, most of them using induction. One of the trade-offs they face is that by using higher frequencies they can shrink the mechanical coils—but that typically requires larger or more expensive electronics.

Two of the players—ConvenientPower Ltd. (Hongkong) and Fulton Innovations LLC (Ada, Mich.) are collaborating to draft an induction standard. Others, such as Powermat (Neve Ilan, Israel) want to pursue advantages they see in their proprietary approaches.

“Unlike other systems that require a lot of space for the charging area, our system requires very little,” said Ron Ferber, president of Powermat. “That's why for our [charging] mats are very thin and our electronics can be scaled to embed into surfaces such as walls and ceilings,” he said.

The company's approach will serve relatively low power devices such as cellphones as well as high power ones like notebook computers, he added. It demonstrated prototypes at CES that will be on sale in the fall for prices ranging from $50 to $140.

By using conduction, Randall claims the WildCharge approach will cost less and be easier to use. Users won't have to lay down devices directly over a coil embedded in a mat because the technology relies on direct metallic contacts in the device linking to a proprietary pattern of pins in the mat.

“No matter how you sit device down, you get one plus and minus,” said Randall.

The approach delivers up to 150W, suitable for charging everything from earbuds to laptops, he said.

To kick start the market, WildCharge licensed the technology to Griffin International which has launched a retail product for rechargeable batteries. But WildCharge hopes to get its products designed into consumer devices, claiming it could deliver end user prices of less than $50 for a pad and $34 for a receiver skin.

“They have benefits in efficiency because they are directly conducting,” but exposed metallic connections on devices could wear away or cause short circuits without cleaver mechanical design, said Schuessler. “We don't see it as the full potential of wireless charging,” he added.

Intel researchers have been exploring longer term approaches that don't require any physical contact. Using a so-called magnetic resonance approach pioneered by MIT, Intel used relatively large coils to deliver 60W of AC power at 10 MHz over three feet to switch on a light bulb at its annual conference in August.

In December, the company powered a small notebook PC in its lab, delivering 12W of DC power over three feet. “We even took the battery out to make sure it wasn't running on battery power,” said Joshua Smith, a principal engineer in Intel's research group.

Intel's goal is to find a way to bring wireless power to its notebook customers. So far its coils are “about the right size to put in a laptop lid,” said Smith.

The group is now working defining the usage model and “looking to find the maximum base power level to transmit safely within global regulations,” Smith said. “We haven't thought much about the cost yet.”

If users are going to be able to use one mat to wirelessly recharge a variety of products from different vendors, the industry needs a standard. The Wireless Power Consortium
aims to deliver one, perhaps before the end of the year.

The group initially aims to deliver a spec for induction systems delivering 5W, probably using a 120 kHz frequency. A follow on spec will target 100W for notebooks.

The consortium currently includes two startups with their own wireless power technology–ConvenientPower and Fulton—as well as component suppliers National and Texas Instruments, potential users Logitech, Philips, and Olympus, battery maker Sanyo and Shenzhen Sang Fei Consumer Communications Co., a Philips ODM.

The group has had three face-to-face meetings since it was formed in December and hopes to attract new members soon. It has outlined market requirements and is now drafting technical specs.

“In the future where there are millions of wireless power devices, the dream is to get to OEM costs of as low as a dollar to enable a receiver,” said Camille Tang, president of ConvenientPower.

“There's a constructive mood in the group, said Schuessler who called the 2009 target “aggressive but not impossible. I think we have good coverage of the technology and intellectual property with Fulton and ConvenientPower participating,” he added.

ConvenientPower has filed about ten patents on its technology that lets users place devices anywhere on its mat. It aims to ship in May retail products for the Nintendo DS and Blackberry Curve, but ultimately aims for OEM design wins.

In late January, TI announced it is working with Fulton. TI suggested it may design special chips to support Fulton's eCoupled technology which sports a similar ability to let users place devices anywhere on an inductive pad. Fulton uses a proprietary protocol that lets users simultaneously charge multiple devices with different charging regimes.

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