ROHM has recently developed 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 the 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.
ST’s automotive NFC Reader IC, the ST25R3914, is an AEC-Q100 grade 1 qualified NFC analog front-end device supporting ISO14443A/B, ISO15693, FeliCa™, and active P2P. Its best-in-class RF performance and its unique Automatic Antenna Tuning function dynamically adapting to challenging metallic environments make it the perfect fit for automotive applications. It comes with a MISRA-C: 2012-compliant RF middleware which helps to shorten the time required for software development.
The automotive 8-bit MCU from ST, STM8AF, provides high performance, wide-ranging choice for memory size, and many package options, contributing to more flexible automotive systems. The MCU features true data EEPROM, CAN and LIN bus, and high operating temperature support up to 150°C. In combination with the NFC function, it can also be used as a controller to manage new types of automotive NFC applications, such as Bluetooth / Wi-Fi pairings for smartphones, “infotainment” using NFC verification, and engine start-up.
Key Features of the Automotive Wireless Charging Solution
- Foreign object detection (detects NFC cards in smart cases)
- 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 without damaging 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 sleeve.
NFC enables seamless infotainment operation via device authentication
- 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.
- Achieves system sharing via personal authentication using NFC
- 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.
ST and Rohm are demonstrating this Qi-standard automotive wireless charging reference design in their booths at the Automotive World 2019 (Tokyo, Jan 16 – 18, 2019). In the future ROHM plans on releasing a sample reference board that will allow users to easily configure a wireless charger for automotive use compatible with the latest Qi standard (EPP) when combined with our Qi certified receiver board (BD57015GWL-EVK-002) already on the market.
ROHM is committed to develop solutions that will enable greater convenience and performance for the rapidly expanding wireless charging market.
