ST25DV64K datasheet(99/220 Pages) STMICROELECTRONICS

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ST25DV04K ST25DV16K ST25DV64K

RF operations

219

RF operations

Contactless exchanges are performed in RF mode as specified by ISO/IEC 15693 or NFC

Forum Type 5. The ST25DVxxx communicates via the 13.56 MHz carrier electromagnetic

wave on which incoming data are demodulated from the received signal amplitude

modulation (ASK: amplitude shift keying). The received ASK wave is 10% or 100%

modulated with a data rate of 1.6 Kbit/s using the 1/256 pulse coding mode or a data rate of

26 Kbit/s using the 1/4 pulse coding mode.

Outgoing data are generated by the ST25DVxxx load variation using Manchester coding

with one or two subcarrier frequencies at 423 kHz and 484 kHz. Data are transferred from

the ST25DVxxx at 6.6 Kbit/s in low data rate mode and 26 Kbit/s in high data rate mode.

The ST25DVxxx supports the 53 Kbit/s in high data rate mode in one subcarrier frequency

at 423 kHz.

The ST25DVxxx follows ISO/IEC 15693 or NFC Forum Type 5 recommendation for radio-

frequency power and signal interface and for anticollision and transmission protocol.

7.1

RF communication

7.1.1

Access to a ISO/IEC 15693 device

The dialog between the “RF reader” and the ST25DVxxx takes place as

follows:

These operations use the RF power transfer and communication signal interface described

below (see Power transfer, Frequency and Operating field). This technique is called RTF

(Reader talk first).

•

activation of the ST25DVxxx by the RF operating field of the reader,

•

transmission of a command by the reader (ST25DVxxx detects carrier amplitude

modulation)

•

transmission of a response by the ST25DVxxx(ST25DVxxx modulates is load clocked

at subcarrier rate)

Operating field

The ST25DVxxx operates continuously between the minimum and maximum values of the

electromagnetic field H defined in Table 214: RF characteristics. The Reader has to

generate a field within these limits.

Power transfer

Power is transferred to the ST25DVxxx by radio frequency at 13.56 MHz via coupling

antennas in the ST25DVxxx and the Reader. The RF operating field of the reader is

transformed on the ST25DVxxx antenna to an AC voltage which is rectified, filtered and

internally regulated. During communications, the amplitude modulation (ASK) on this

received signal is demodulated by the ASK demodulator

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