Freescale turns up the power: charges 15-W wirelessly

Technology News |
By eeNews Europe

The chips are the first to handle up to 15 W using the Qi technology defined by the Wireless Power Consortium.

"Today’s mobile products offer a broader range of features, functionality and form factors than ever before, requiring developers of wireless charging systems to accommodate larger batteries and enable faster recharge speeds," Denis Cabrol, Freescale’s MCU group director of global marketing and business development, said in a release.

Freescale’s WCT1012/WCT1111 transmitter chips — offered in standard and premium versions — and its WPR1516 receiver chip are geared for mobile devices with bigger batteries. They enable a recharge that’s up to three times faster than 5 W predecessors, said Freescale’s Randy Ryder.

"In a typical 5 W system that’s producing 1-A current, you can charge in one hour. With 15 W, in theory, you could cut that charge time by a third by improving power," according to Ryder, wireless charging lead for Freescale’s microcontroller division and a representative on the Power Matters Alliance.

Transmitter block diagram. Source: Freescale.

The Apple iPad and Samsung Galaxy Tab have approximately 12 W power ratings, which have yet to be addressed by existing wireless charging devices. The 15 W spec will also enable mobile phones that have fast charging capabilities, a capability expected to grow rapidly in 2015, according to IHS analyst Ryan Sanderson who shared his thoughts:

I personally believe there is more value in a wireless charger at 15 W that can charge multiple devices of different power classes in multiple scenarios than one that is just targeted at charging media tablets. If the solution can charge your media tablet (at 12 to 15 W), your phone (with a choice of standard or fast charging) and a wearable device (which could be anything from 0.5 W to 3 W+) at the same time and manage this process, I see that as a valuable product.

The 100 MHz transmitter runs an ARM M0+ core with less than a 30 milliamp loop current, a low power sweet spot Ryder attributes to its use in power-supply applications. The core also has some DSP functionality which helps reduce system losses and improve charging capability.

Receiver circuit. Source: Freescale.

Freescale’s premium transmitter allows for additional programability, access to flash on the chip, and extra IOs to build applications such as a charger that supports multiple devices at once. The receiver supports LDO and buck output power topologies.

The Freescale chips support two standards based on magnetic induction using closely coupled coils — Qi and a separate spec from the Power Matters Association. While Ryder believes the bridge products similar to those from MediaTek will become commonplace, Freescale’s devices don’t support the resonant standard of the Alliance for Wireless Power that uses loosely coupled coils.

Inductive charging produced a pretty healthy ecosystem. We’re seeing the adoption rate increase because cost is coming down and technology has improved a lot in terms of efficiency and value, Ryder said. "Road maps from the industry focus on two key targets: extending power levels beyond 5 W and including resonance as part of the specification," he added.

Freescale will sample boards and controllers in the first quarter of 2015 and has done limited sampling with unnamed customers. Ryder said the company has early engagements with phablet producers to test the 15 W technology.


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