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and resonance. The system is a stand that can hold and charge the equivalent of two smartphones. It’s built over a single coil and single IC, with a target segment of mobile applications in the rante of 1/2 Watt to 15 Watts. “The device is smart enough to figure out which charger it is, and then it charges appropriately. The technology goes into virtually anything you want from a Bluetooth headset to an electric vehicle,” Mark Estabrook, director of strategic marketing at MediaTek, told us. “This is something of a bridge product, we think, meaning we think it will help get the industry from where it is today - the inductive - to the resonant technology which will be developed over the next 2-3 years.” Mark Hunsicker, senior director of product management at Qualcomm and a treasurer for the A4WP, said there is an opportunity for a dual-mode bridge transitional receiver that implements inductive and resonance charging. There’s not much legacy product in the marketplace. Nevertheless, “I’m not a big fan,” Hunsicker said. “It’s not a highly desirable solution from the consumer side, because there’s not a great deal of commonality between the two technologies. There are increased materials and area costs, because there’s not a lot of synergy between the two technologies.” Mohit Bhushan, US marketing manager at MediaTek, told us his company is working on resonance solutions to complement future generations of its recently released LTE SoC. “The industry tends to use ‘inductive’ and ‘resonant’ as different technologies, though in reality, both are based on inductive technology,” Sanderson said via email. “Those which use magnetic resonance are just a highly tuned inductive solution.” Resonant transfer relies on loosely coupled coils that transfer electricity along the same resonant frequency. A capacitance plate, which can hold a charge, attaches to each end of the coil and then produces a resonant frequency from the inductance of the coil and the capacitance of the plates. Resonance advocates have championed the technology for the ability to charge multiple devices at once with freedom of placement - the device can be more than 10 inches above or to the side of the charging plate. Distance can also be increased by placing a repeater between the device and charging place. The A4WP says resonance (or, its version, Rezence) can charge devices though surfaces 40 to 50mm thick. “A resonance-based approach gives the opportunity to have multiple devices charging and multiple device types. Competing forums can do some of that, but can’t meet all the requirements,” Hunsicker said. “I think you’re seeing the acknowledgement of that, because those other forums have launched resonant working groups. They’ve acknowledged that the resonant-based approach is going to overtake inductive.” The A4WP seems best aligned to lead this charge. Its member companies include Samsung, Texas Instruments, Dell, and WiTricity, whose resonance technology IP have been used in Intel products. The group recently announced a partnership with a former inductive group, the Power Matters Alliance. Powering your next design. Let us be your power expert. We understand that you don’t have the time to master every aspect of electronic design. As a leading manufacturer of power supplies we are here to collaborate with you to ensure your next project is a success. Dc-Dc Converters www.cui.com/PowerExpert Novum® Advanced Power Ac-Dc Power Supplies www.electronics-eetimes.com Electronic Engineering Times Europe March 2014 27


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