New Industry Products

Qi Wireless Charger Reference Design with NFC for Automotive Use

January 16, 2019 by Scott McMahan

ROHM plans on releasing a sample reference board in February that lets users easily configure a wireless charger for automotive use compatible with the latest Qi standard (EPP), when combined with ROHM's already available Qi certified receiver board (BD57015GWL-EVK-002).

ROHM is currently exhibiting the as yet unreleased reference board integrating the wireless charging solution at the 11th International Car Electronics Technology Show at Tokyo Big Sight from January 16-19, 2019.

The reference board comes from the company's development of an automotive wireless charging solution that integrates NFC communication. This solution couples ROHM's automotive-grade (AEC-Q100 qualified) wireless power transmission control IC (BD57121MUF-M) integrating ST Microelectronics' the NFC Reader IC (ST25R3914) and 8-bit microcontroller (STM8A series).

As well as being compliant with WPC's Qi standard, it supports 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 offers some spatial freedom in vehicle applications and provides 2.7x greater charging range compared to single coil configurations. This wider charging area means that consumers do not need to worry much about perfectly aligning their smartphones to the charging area so they can charge wirelessly.

Wireless charging technology, often used in portable devices including smartphones to enhance the connector's safety and resistance to water and dust, is seeing expanded adoption in infrastructure applications such as vehicles, airports, hotels, cafes, and similar public locations. Presently, the European Automotive Standards Group (CE4A) has already adopted Qi, the most popular wireless charging standard as the charging standard in vehicles. By 2025 it is predicted that the majority of cars will come with Qi-based wireless chargers.

In the meantime, NFC communication offers user authentication to allow Bluetooth/WiFi communication with infotainment systems, lock and unlock doors, and start engines. NFC also enables vehicle setting customization for multiple drivers including mirror and seat positioning, infotainment pre-sets, and navigation destination pre-sets.

"ROHM's adoption of the ST NFC products and 8-bit microcontroller for their Qi-standard automotive wireless-charging reference design shows that ST's broad product lineup has big potential for creating new and valuable automotive functions," said Hiroshi Noguchi, Japan country manager, STMicroelectronics. "We anticipate many auto manufacturers will see wireless charging as an important added value that will provide ST with another way to contribute to a more comfortable driving experience for consumers."

STMicroelectronics NFC Reader ICs

The ST25R3914/3915 automotive-grade NFC Reader ICs are compatible with ISO14443A/B, ISO15693, FeliCa™ and ISO18092 (NFCIP-1) Active P2P. They incorporate a high-performance analog front end that boasts best-in-class receiver sensitivity for delivering reliable foreign-object detection performance in vehicle center consoles.

The ST25R3914 includes ST's proprietary Automatic Antenna Tuning function, which adapts to the surrounding environment changes to minimize the effects of metallic objects near the reader antenna, like keys or coins placed on the center console. ST now offers MISRA-C: 2012 compliant RF middleware to help customers reduce their software development effort.

STMicroelectronics Automotive 8-bit MCUs

The STM8A, high-performance automotive 8-bit MCU series, comes in a variety of packages and memory sizes. Furthermore, the pin-compatible lineup lets users select the best product matches for required functions and performance.

Devices with embedded data EEPROMs are also offered, such as CAN-equipped models with an extended operating temperature range up to 150C, making them perfect for various automotive applications.

Key Features of Evaluation Board

  • Foreign object detection (detects NFC cards in smart cases)
  • Per the Qi standard, an integrated foreign object detection function detects metallic objects to prevent deformation or damage due to excessive heat generation if a metallic object is placed between the transmitter and receiver.
  • The designers were confronted with the challenge of ensuring detection of the NFC antenna without having the magnetic field damage the NFC card. They were able to achieve this by integrating an NFC communication function that enables detection of the NFC card even when inserted in a smartphone case or sleeve.

NFC Authenticates for Seamless Infotainment Operation

  • Previously, when connecting smartphones to infotainment systems it was necessary to perform manual pairing for each device. However, by coupling Qi wireless charging with NFC communication, ROHM enabled charging mobile devices such as smartphones as well as performing Bluetooth or WiFi pairing at the same time via NFC authentication.
  • A user places a smartphone on the charging pad to automatically initiate screen sharing with the infotainment and navigation system.