Wireless battery charger controller offers customisable power transfer

March 03, 2015 // By Graham Prophet
The STWBC digital controller for wireless battery charger (WBC) transmitters from STMicroelectronics offers what the company terms as the most flexible and efficient solution for controlling power transfer from a WBC transmitter (TX) to a receiver (RX).

The device is intended foruse in WBC-enabled phones, wearables, and other battery-powered devices that use electromagnetic induction for re-charge. As a member of the Qi Wireless Power Consortium and the PMA (Power Matters Alliance), ST ensures full compatibility with these wireless-charging protocols and says it is one of the first companies that hold certification for the newest Qi 1.1.2 A11 standard.

The STWBC performs all the essential functions for transmitter control: it is able to precisely control the amount of transmitted power to match the requirements of the receiving unit in terms of maximising the efficiency of the power transfer and minimising any increase in operating temperature. The digital feedback between TX and RX units also allows the detection of metal objects close to the receiver (foreign object detection or FOD) that could result in potential hazards, enabling the STWBC to stop power transmission when such objects are detected.

Features of the STWBC include:

Multiple Qi and PMA standards support

Qi 1.1.2 A11-certified

Up to 5W power capability for mobiles, wearables, remote controls

Native support for half-bridge and full-bridge topologies

5V operating voltage.

STWBC comes with firmware options to offer customers the ability to personalise their end product without the need for external microcontrollers:

- A turn-key Qi 1.1.2 A11 certified solution (reference design board STEVAL-ISB027V1), fully interoperable with Qi-enabled mobile phones

- API (application programming interface) access to customise the underlying firmware, for example modifying the behaviour of the LEDs or GPIOs in response to the receiver behaviour and supporting I²C and UART communication within a network

The device is offered together with a complete ecosystem to support customers in building their applications, including the Qi 1.1.2 A11-certified reference design board (STEVAL-ISB027V1), API libraries and documentation to develop software customisations, as well as a comprehensive graphical user interface to monitor real-time performance and diagnostics.

Housed in a VFQFPN32 package, the STWBC is available at $3.00 (1000).

STMicroelectronics; www.st.com