The PTX100W NFC charger IC provides an output power at the charging device’s antenna of >2.5W. The high output power enables much faster charging, making it viable for manufacturers of consumer devices that only have space for a small antenna to eliminate the wired charging circuit from next-generation product designs.
Manufacturers of mobile and wearable devices are looking to replace wired charger connections with wireless charging, because of its convenience, design flexibility and reliability benefits. Qi wireless charging, popular in smartphones, is unsuitable for smaller devices because it requires a large antenna and costly circuitry. Qi antennas also lose charging efficiency unless precisely aligned.
NFC wireless charging benefits from small antenna size with high tolerance of antenna misalignment, and because of the NFC protocol’s support for data communication with a host such as a smartphone. However, adoption has been held back due to the low output power provided by conventional NFC controller ICs.
The PTX100W now makes wireless charging via an NFC interface suitable for any device with a battery smaller than 500mAh.
The PTX100W uses a patented sine wave architecture developed by Panthronics. This architecture disposes of the lossy EMC filter circuitry required in conventional NFC controllers, which have a square-wave output signal. With the elimination of the EMC filter, it is possible to achieve an antenna matching impedance some two times lower than that of a conventional solution which has an EMC filter. These two features enable the PTX100W NFC charger to drive much higher power through an NFC antenna than existing NFC ICs, while minimising the power losses introduced by external components.
The PTX100W also supports NFC data communication while charging – data exchange operations are fully compliant with NFC Forum specifications. Panthronics’ DiRAC (Direct-to-Antenna Connection) technology eliminates the EMC filter, but also allows the receiver to directly sense antenna signals with high dynamic range via its patented receiver input stage.
Panthronics, working with Renesas, has developed a demonstration design of a wireless charging system for a wearable device, based on the PTX100W and a Renesas Synergy S128 MCU. The PTX100W NFC charger, which has a standard serial peripheral interface for communication, is compatible with any standard low-power MCU device.