New Industry Products

# Digital Controller for Wireless Charger Transmitters for Qi Multicoil Designs

September 27, 2018 by Paul Shepard

The STMicroelectronics' STWBC-MC 15W wireless battery-charger transmitter can control multiple charging coils, making charging less dependent on the precise position of the battery-powered device. Compliant with the latest Qi® 1.2.4 specification, the STWBC-MC is the first transmitter specifically designed to support the Qi MP-A15 EPP (Extended Power Profile) topology.

In addition to detecting a valid receiver and selecting the most efficient coil for power transfer, it ensures extended Foreign Object Detection (FOD) through bi-directional communication with the receiver. The STWBC-MC also supports the proprietary wireless fast-charge extensions of leading smartphone manufacturers.

To ensure fast and stable charging for all types of devices, the STWBC-MC monitors coil current and voltage. By integrating a digital DC-DC controller, it delivers the required power to the coil at a fixed frequency and so minimizes interference with other systems inside smartphones and tablets.

Given the EU's intention to extend the scope of the Radio Equipment Directive (RED) to include wireless-charging transmitters, and restrict H-field emissions above 145kHz to -5dBm, the STWBC-MC's low-EMI design eases compliance.

ST's patented triple-path modulation technique for communication between the transmitter and receiver increases noise immunity and the IC's low standby consumption minimizes wasted energy when not charging.

Users can start development quickly using the STEVAL-ISB047V1 evaluation kit for the STWBC-MC and the STSW-STWBCGUI graphical user interface for ST's STWBC transmitter ICs. The GUI can be used to download the STSW-ISB047FW dedicated firmware for the STWBC-MC, and to monitor performance and fine-tune parameters.

The STWBC-MC is in production, priced from $3.375 for orders of 1000 pieces. The STEVAL-ISB047V1 is available now from st.com or distributors, for$170.