Interface chip drives down the cost of adding high data-rate NFC capability to microcontrollers

November 06, 2012 // By Paul Buckley
Implementing instant, high-speed Near Field Communication (NFC) between two independent devices has been made easier and cheaper with the introduction of the AS3953 interface chip developed by ams.

The AS3953 offers a high data-rate interface between a NFC device such as a smartphone and any host microcontroller with a standard Serial Peripheral Interface (SPI).

Operating on energy harvested from an NFC reader’s RF emissions, the AS3953 NFiC (Near Field Communications interface Chip) requires no external power source and at most one external component (a capacitor). The device enables system designers to add full bi-directional NFC capability at a total cost less than half that of a typical NFC reader implementation, which can require as many as 20 external components.

The AS3953 is fully compliant with NFC Forum specifications (NFCIP-1 target at 106 kbps) and the ISO14443A industry standard (up to 848 kbps, to Level 4). This means that it can be used in contactless smart cards and as an NFC Forum-compatible interface tag, and can establish instant communication with any NFC-enabled phone in close proximity (<10 cm).

The AS3953 is expected to find uses in a wide variety of applications, including contactless passive programming of MCU-based systems, smart cards with displays, smart retail shelf labels, sensors and ultra low-power data loggers, medical devices, and secured NFC Bluetooth pairing.

It can also enable innovative new approaches to system designs by using an NFC-enabled smartphone as a display host and system controller for normally stand-alone devices, eliminating the requirement for the slave device to have its own display and processor.

The AS3953 features a configurable wake-up interrupt, enabling a zero-power system design while in shut down. It also contains a complete analog front end, 1kB of internal EEPROM, and a 4-wire SPI with a 32-byte FIFO. The device can draw up to 5 mA of harvested energy from the external magnetic field, and includes an internal power management circuit that can supply harvested energy to the application. This makes the AS3953 ideal for use with battery-powered and portable microcontroller-based devices.

The company has also announced a new reference design developed