Wireless charging – what’s new?

The convenience of having your mobile charged wirelessly, while you sip coffee at the corner shop, is now fast approaching reality with passing time. Wireless charging is now entering a phase where manufacturers are turning up the power so that it is possible to charge wirelessly handheld medical equipment, tablets and larger phablets. For example, a new set of receivers and transmitters from Freescale can now handle up to 15W. These chips use the Qi technology that the Wireless Power Consortium has defined.

According to the MCU group director of global marketing and business development at Freescale, the latest mobile products are offering a broader range of features. As compared to earlier, current products have bigger form factors and improved functionalities, necessitating larger batteries. Accordingly, wireless charging systems must also upgrade to accommodate the larger power requirements and faster recharge speeds.

Freescale’s transmitter chips – WCT1012/WCT1111 – are available as standard and premium versions. Together with the receiver chip – WPR1516 – Freescale now offers wireless charging system for mobile and other devices with bigger batteries. Compared to their 5W predecessors, the new chipsets from Freescale can recharge more than three times faster.

The typical 5W charging system produces one ampere of current, allowing charging to be completed in one hour. The new chips handle 15W and theoretically, should cut down the charging time by a third because of improved power handling capacity.

Modern smart devices such as the Samsung Galaxy Tab and the Apple iPad have power ratings reaching 12W, but existing wireless charging devices cannot handle this power. According to IHS Analysts, fast charging capabilities are expected to grow rapidly in and after 2015. The new 15W specifications will accommodate such devices allowing them to be charged faster.

Manufacturer’s feel that a 15W wireless charger has more value since it is able to charge simultaneously many devices belonging to different power classes in multiple scenarios. Compare this to a charger that targets charging only media tablets. For example, the new wireless chargers will charge not only your media tablets consuming 12-15W, but also manage the charging of your phone at standard or fast charging and a wearable device consuming 0.5 to 3W or more. That certainly makes it a valuable product to own.

Inside the Freescale transmitter is a 100MHz DSC core that consumes less than 30mA loop current. DSP functionality within the core helps to reduce the system losses and improve its capability for charging. Additional programmability built into the premium transmitter provides access to flash memory on the chip. Extra IOs on the transmitter device allows building of applications such as chargers that support multiple devices at the same time. On the other hand, the Freescale receiver has capabilities to support buck output and LDO power topologies.

The Freescale chips work on magnetic induction principles using closely coupled coils. The chips comply with two standards – Qi and another specification from the Power Matters Association. However, the Freescale devices are not compatible to the resonant standard using loosely coupled coils that the Alliance for Wireless Power follows. According to Freescale, inductive charging is healthy for the ecosystem.