ST25R3911B Datasheet, PDF (1/129 Pages) STMicroelectronics – Automatic antenna tuning system providing tuning of antenna LC tank

ST25R3911B
High performance HF reader / NFC initiator
with 1.4 W supporting VHBR and AAT
Datasheet - production data
QFN32
Wafer
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
• 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
Description
The ST25R3911B 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) 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.
December 2016
This is information on a product in full production.
DocID029656 Rev 2
1/129
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