Wireless load via NFC antenna

Wireless charging of mobile devices is picking trip, the upcoming Nokia's flagship Lumia 920 about to be factory-Qi-compatible. Now Renesas announces three semiconductor devices that use the wireless store up to 10 centimeters distance antennas, which are also suitable for Nahfunktechnik NFC. For samples of the three controller chips will each Renesas have $ 6 - that would be for the series products but probably too much. The mass production is scheduled for the 2013th

The tiny controller chip NF20 assumes the NFC communication, the transmitter controller controls R2A45801 through MOSFET RJK1028 to the transmitting antenna and in the mobile device the R2A4570 sits as a receiver. It includes a charging circuit for a single lithium-ion cell (3.7 volts), but also provides DC voltage to the device, as well as 1.8 to 3 volts for the RF20 on the receiver side. Also assumes the R2A4570 switching between different charging sources such as (micro) USB port or charger input.

Renesas specifies the communicable charging power not exactly, probably it is not higher than that of Qi, ie less than 5 watts. Thus, the loading of a typical smartphone battery would last with 5.5 Wh capacity significantly more than 1 hour, if we include loading and transformer losses. IDT has therefore announced in March a Qi-compatible IC couple that is in a proprietary mode create about 7.5 watts.

Intel is working again with IDT in a charging system that will be integrated into Ultrabooks. As explained at the IDF now, is the advantage of Wireless Charging Technology (WCT) supposedly. Longer reach or less reliance on the antenna orientation Intel will ensure higher losses. Intel uses the resonance technique WREL while Qi largely inductive coupling. With 5 watts of power from the battery Ultrabook Intel will ultimately provide 3 watt charging power on smartphone battery.

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