ST25R3911B-AQFT

ST25R3911B

High performance HF reader / NFC initiator with 1.4 W supporting VHBR and AAT

Description

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 ST25R3911B is positioned perfectly for the infrastructure side of the NFC

system, where users need optimal RF performance and flexibility combined with low

power.

Thanks to automatic antenna tuning (AAT) technology, the device is optimized for

applications with directly driven antennas. The ST25R3911B is alone in the domain of

HF reader ICs as it contains two differential low impedance (1 Ohm) antenna drivers.

The ST25R3911B includes several features that make it very suited for low power

applications. It contains a low power capacitive sensor that can be used to detect the

presence of a card without switching on the reader field. The presence of a card can

also 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 contains 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 (capacitive, phase or amplitude).

The ST25R3911B is designed to operate from a wide (2.4 V to 5.5 V) power supply

range; peripheral interface IO pins support power supply range from 1.65 V to 5.5 V.

Features

• ISO14443A, ISO14443B, ISO15693 and FeliCa™

• Supports VHBR (3.4 Mbit/s PICC to PCD framing, 6.8 Mbit/s AFE and PCD to

PICC framing)

• Capacitive sensing - Wake-up

• Automatic antenna tuning system providing tuning of antenna LC tank

• Automatic modulation index adjustment

• AM and PM demodulator channels with automatic selection

• DPO (Dynamic power output)

• Up to 1.4 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 MHz or 27.12 MHz crystal with

fast start-up

• 6 Mbit/s SPI with 96 bytes FIFO

• Wide supply voltage range from 2.4 V to 5.5 V

• Wide temperature range: -40 °C to 125 °C

•QFN32, 5 mm x 5 mm package