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

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November 2016

DocID029999 Rev 1

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ST25R3909

ISO-14443 A/B, 13.56 MHz mid-range reader

Data brief

Features

• Close loop adjustment of ASK modulation for

accurate control of modulation depth in case of

ISO-14443 B protocol

• Low power (3.5 μA) NFC target mode

• AM/PM demodulator

• Accurate RF envelope measurement (8-bit A/D

converter)

• High output power at 3.3 V power supply:

– Up to 700 mW in case regulator is

externally shorted

– Up to 500 mW in case of differential output

when antenna trimming is used

– Up to 125 mW in case of single ended

output when antenna trimming is used

• Squelch for gain reduction, to compensate for

noise generated by transponder processing

• Transparent mode

• Amplitude and phase measurement

• Supporting 13.56 MHz and 27.12 MHz quartz

oscillators with fast start-up

• Supply voltage range from 2.4 to 3.6 V

• Wide temperature range: -40 ºC to 85 ºC

• Package: 32-pin QFN32, 5 mm x 5 mm

Description

The ST25R3909 is a high performance

13.56 MHz RFID reader, with two differential, low

impedance (1.5 Ohm) antenna drivers.

These drivers are unmatched, allowing the

ST25R3909 to deliver up to eight times the output

power of a standard HF reader IC using the same

power supply voltage, and reducing in half the

power consumption at the same output power.

The ST25R3909 can operate already at 2.4 V,

with a low power operating mode of 5 mA, making

it perfectly suited for portable or battery-powered

applications.

For applications where high power is required the

ST25R3909 can deliver up to 700 mW, thus

avoiding the need for complex external booster

circuitry.

The component count and complexity of the

design is further reduced through automatic

modulation depth adjustment.

The analog front end (AFE) is complemented by a

highly integrated data framing engine for both

ISO-14443 A and B. This includes data rates up

to 848 kbit/s, with all framing and synchronization

tasks on board, and enables to build a complete

HF RFID reader using only a low end

microcontroller.

The ST25R3909 supports reader to tag and Peer

to Peer communication using the NFCIP-1 active

communication mode with a 106 kbps data rate.

Other standard and custom protocols, such as

transparent mode. The ST25R3909 features a

SPI, which enables bi-directional communication

with the external microcontroller.

QFN32

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