Renesas Electronics, a premier supplier of advanced semiconductor solutions, has developed the near field communication (NFC) [Note 1] wireless charging system to eliminate the power cable for charging and increase efficiency of those systems. Renesas supplies the essential components needed to build a system: the NFC microcontroller (MCU) RF20, the power transmitter IC R2A45801, and the power receiver IC R2A45701. Renesas also provides the total kit including peripheral general-purpose devices (e.g. power semiconductor devices) as a system solution.
Wireless charging is starting to become popular in products such as smartphones. It eases battery charging of portable devices and makes cables and connectors redundant.
Today’s existing wireless charging systems typically couple two antennas, one for receiving and one for transmitting power. The gap between and the combination of the two antennas highly influence the efficiency of the charging power. Such existing wireless charging systems limit the effective charging area significantly. In consequence the alignment of the transmitting and receiving antennas greatly reduces the freedom of product design.
The Renesas NFC wireless charging technology widens the charging area to about 10 cm. It incorporates the technology of the existing NFC MCU, and utilizes the NFC antenna to implement a wireless charging system that uses a single RX antenna for NFC communication and receiving power, thereby improving reliability while reducing the bill of material of a receiver design. To make it easier for developers to incorporate this system into their mobile devices, Renesas developed the NFC MCU, the power receiver IC, and the power transmitter IC built around the company’s proven power technology. These new products are the main components necessary to implement a wireless charging system and are supplied as a total solution kit.
Key Features of the Renesas’ Wireless Charging System
The NFC wirel
ess charging system solution not only makes the charging cable-free, but also makes it possible to achieve a new, more flexible level of wireless connectivity by fusing NFC and wireless charging technology. The main features of the system are described below.
1) Power transmission and data reception via a single antenna with NFC
Conventional wireless power receiver with additional short range communication capabilities requires two antennas, one for data transmission and one for receiving power. In an NFC-based system the receiver uses a single antenna, contributing to more compact and thinner mobile handsets.
2) Expansion of charging area with NFC. The exclusive technology employing NFC makes it possible to widen the charging area to about 10 cm, making it possible to build a wireless charging system relatively unaffected by positioning deviation.
The flexibility in mobile handset power receiver positioning allows more flexible design for handsets and power transmitters.
3) Ability to build wireless charging systems with a high level of safety. NFC supports bi-directional intercommunication, so it is possible to verify (determine) whether a device can be charged before the supply of power begins. This increases the safety of the wireless charging.
4) A single NFC MCU for both wireless charging and conventional contactless smart card applications
Based on the NFC standard, the system supports not only wireless power supplies but also existing contactless smart card applications. This enables the designing of more compact mobile handsets. Renesas has submitted the new solution to the Wireless Charging Task Force of the NFC Forum [Note 2] as part of encouraging the broad adoption of NFC wireless charging systems.