ROHM: automotive-grade wireless charging solution with NFC communication

ROHM has recently announced the development of an automotive wireless charging solution with integrated NFC communication. This solution combines ROHM’s automotive-grade (AEC-Q100 qualified) wireless power transmission control IC (BD57121MUF-M) with STMicroelectronics' NFC Reader IC (ST25R3914) and 8-bit microcontroller (STM8A series). In addition to being compliant to WPC’s Qi standard supporting EPP (Extend Power Profile) that enables the charger to supply up to 15W of power, the multi-coil design enables a wide charging area that provides some spatial freedom in vehicle applications (2.7x greater charging range vs single coil configurations). This means that consumers do not need to worry much about exactly aligning their smartphones to the provided charging area in order to be able to charge wirelessly.

Wireless charging technology, commonly used in portable devices such as smartphones to improve the safety and resistance to water and dust of connectors, is seeing increased adoption in infrastructure applications including vehicles, hotels, airports, cafes, and similar public locations. At present, Qi, the most popular standard, has already been adopted by the European Automotive Standards Group (CE4A) as the charging standard in vehicles, and by 2025 it is predicted that most cars will be equipped with Qi-based wireless chargers.

Meanwhile, NFC communication provides user authentication to allow Bluetooth/WiFi communication with infotainment system, lock/unlock the doors, and allow engine start. NFC also enables vehicle setting customization for multiple drivers such as seat and mirror positioning, infotainment pre-sets, and navigation destination pre-sets.

Per the Qi standard, a foreign object detection function for detecting metallic objects is included to prevent deformation or damage from occurring due to excessive heat generation in the event a metallic object is placed between the transmitter and receiver. This time, however, designers were faced with the challenge of ensuring detection of the NFC antenna can damage the NFC card by the magnetic field. This was achieved by integrating an NFC communication function that enables detection of the NFC card even when inserted in a smartphone case or the like.

Previously, when connecting smartphones to infotainment systems it was necessary to perform manual pairing for each device. However, by combining Qi wireless charging with NFC communication ROHM made it possible to not only charge mobile devices such as smartphones but also perform Bluetooth or WiFi pairing at the same time through NFC authentication. To use, simply place a smartphone on the charging pad to automatically initiate screen sharing with the infotainment and navigation system.

In the future, all vehicles are expected to utilize NFC protocol to connect smart devices with the onboard system to provide shared functionality that does not rely on traditional keys or dedicated cards.

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