In basic operation, the AS3956 acts as a stand-alone Type 2 tag conforming to the NFC Forum standards and supporting NFC communication with a reader. In addition, either of two data-transfer modes for host controller communication can be selected:
- Extended Mode, a self-timed data transfer mechanism using standard Type 2 tag commands, minimizing software overhead on the host controller;
- Tunnelling Mode to implement ISO14443A Level 4 PICC emulation in line with EMVCo requirements or custom protocols.
The AS3956 includes an energy-harvesting capability, drawing energy from the incoming RF field generated by an NFC reader, and supplying up to 5 mA to an external device. Energy harvesting is useful as a cost effective, small footprint alternative to standard wireless charging, to extend battery lifetime in biometric smart cards, or to implement fully passive wireless sensing solutions, as required (for example) in smart insulin pens.
The AS3956 is available in a miniature chip-scale package (CSP) 0.3-mm high, and with a 1.8- x 1.4-mm footprint: as well as in a 3- x 3-mm MLPD package. Pricing is $0.53 (1000).