General Description
The AS3953A NFC interface IC (NFiC) delivers low cost, ultra low
power NFC Forum functionality to multiple different
applications. The AS3953A is a analog front-end with integrated
14443A data framing and SPI interface. It is designed to create
a fast data link between an ISO 14443A reader device (PCD) and
a microcontroller. The AS3953A is passively powered meaning
that it can be supplied from the PCD magnetic field, eliminating
the need of a continual external supply. This makes the
AS3953A perfect for wireless communication to a low-power
battery powered device.
The AS3953A is used with an appropriate antenna coil
connected to the terminals LC1 and LC2, and behaves as a
normal passive ISO 144443A tag (PICC). After the anti-collision
protocol is passed, the PCD sends a Wake-Up command, which
wakes up the microcontroller by sending an interrupt. From this
point onwards, the AS3953A serves as a data link between the
microcontroller and the PCD. AS3953A can also operate as
NFCIP-1 target at 106 kbit/s.
The AS3953A includes an onboard EEPROM that can be
accessed either from the PCD or from the microcontroller via
the SPI interface. This built-in flexibility makes it ideal for two
types of applications:
• Where personalization data is programmed by the PCD
(even in case the SPI side is not powered) and it is later
read by microcontroller through SPI interface.
• Where log data is stored periodically by the
microcontroller and can then be read by the PCD even
when the microcontroller is not powered.
A regulated power supply voltage extracted from the PCD field
is also available on a pin and can be used as power supply for
external circuitry. For example, an external microcontroller and
a sensor could be powered from the PCD field combined with
pass through data rates up to 848kbit/s, which means the
AS3953A is ideal for contactless passive programming of MCU
systems. The AS3953A can also operate as a stand-alone ISO
14443A tag.
The AS3953A supports ISO 14443A up to Level-4, meaning a
contactless smart card or an NFC forum compatible tag (Tag
Type 4) can be built. Having a NFC Forum compatible tag
interface allows the AS3953A to be used in an application where
a standard NFC enabled phone is used as a PCD.
Applications
Passive wake-up
Multipurpose HF interface to a controller
Low power or passive programming
Ultra low power data logger
RFID programmable configuration EEPROM
ISO 14443A smart card
NFC Forum Tag Type 4
Bluetooth and Wi-Fi pairing