Features
• ISO 18092 (NFCIP-1) Active P2P
• ISO14443A, ISO14443B, ISO15693 and
FeliCa™
• Supports HBR up to 848 kbit/s PICC to PCD
and PCD to PICC framing
• Inductive sensing - Wake-up
• Automatic modulation index adjustment
• AM and PM (I/Q) demodulator channels with
automatic selection
• Up to 1 W in case of differential output
• User selectable and automatic gain control
• Transparent and Stream modes to implement
MIFARE™ Classic compliant or other custom
protocols
• Possibility of driving two antennas in single
ended mode
• Oscillator input capable of operating with 13.56
or 27.12 MHz crystal with fast start-up
• 6 Mbit/s SPI with 96 bytes FIFO
• Wide supply voltage range from 2.4 to 5.5 V
• Wide temperature range: -40 °C to 125 °C
• VFQFPN32, 5 mm x 5 mm package with
wettable flanks
• WLCSP, 3.0 mm x 2.8 mm package

Description
The ST25R3912 is a highly integrated NFC initiator / HF reader IC, including the analog front end (AFE) and a highly integrated data framing system for ISO 18092 (NFCIP-1) initiator, ISO 18092 (NFCIP-1) active target, ISO 14443A and B reader (including high bit rates), ISO 15693 reader and FeliCa™ reader. Implementation of other standard and custom protocols like MIFARE™ Classic is possible using the AFE and implementing framing in the external microcontroller (Stream and Transparent modes).
The ST25R3912 is positioned perfectly for the infrastructure side of the NFC system, where users need optimal RF performance and flexibility combined with low power.
The device is optimized for applications with directly driven antennas. The ST25R3912 is alone in the domain of HF reader ICs as it contains two differential low impedance (1 Ohm) antenna drivers.
The ST25R3912 includes several features that make it very suited for low power applications. The presence of a card can be detected by performing a measurement of amplitude or phase of signal on antenna LC tank, and comparing it to the stored reference. It also contain a low power RC oscillator and wake-up timer that can be used to wake up the system after a defined time period, and to check for the presence of a tag using one or more low power detection techniques (phase or amplitude).
The ST25R3912 is designed to operate from a wide (2.4 to 5.5 V) power supply range; peripheral interface IO pins support power supply range from 1.65 to 5.5 V.