This is information on a product still in production but not recommended for new designs. For further information contact

your local STMicroelectronics sales office.

November 2016

DocID030000 Rev 1

1/3

ST25R3911

High performance HF reader / NFC initiator

with 1 W supporting VHBR and AAT

Data brief

Features

• ISO 18092 (NFCIP-1) Active P2P

• ISO14443A, ISO14443B 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 (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 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

Description

The ST25R3911 is a highly integrated

HF reader / NFC initiator 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) 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 ST25R3911 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 technology

the device is optimized for applications with

directly driven antennas. The ST25R3911 is alone

in the domain of HF reader ICs as it contains two

differential low impedance (1 Ohm) antenna

drivers.

The ST25R3911 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 ST25R3911 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.

QFN32

www.st.com