ST25TV02K datasheet(25/90 Pages) STMICROELECTRONICS

25 / 90 page

RF operations

Contactless exchanges are performed as specified by ISO/IEC 15693 and NFC Forum Type 5. The

ST25TV02K/512 communicate 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 ST25TV02K/512 load variation using Manchester coding with one or two

subcarrier frequencies at 423 kHz and 484 kHz. Data are transferred from the ST25TV02K/512 at 6.6 Kbit/s in low

data rate mode and 26 Kbit/s in high data rate mode. The ST25TV02K/512 support the 53 Kbit/s data rate mode

in one sub-carrier frequency at 423 kHz.

The ST25TV02K/512 follow ISO/IEC 15693 and NFC Forum Type 5 recommendation for radio-frequency power

and signal interface and for anticollision and transmission protocol.

6.1

RF communication

6.1.1

Access to a ISO/IEC 15693 device

The dialog between the “reader” and the ST25TV02K/512 take place as follows:

These operations use the 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 ST25TV02K/512 by the operating field of the reader,

•

Transmission of a command by the reader (ST25TV02K/512 detect carrier amplitude modulation)

•

Transmission of a response by the ST25TV02K/512 (ST25TV02K/512 modulate is load clocked at subcarrier

rate)

Operating field

The ST25TV02K/512 operate continuously between the minimum and maximum values of the electromagnetic

field H defined in Table 153. RF characteristics. The Reader has to generate a field within these limits.

Power transfer

Power is transferred to the ST25TV02K/512 by radio frequency at 13.56 MHz via coupling antennas in the

ST25TV02K/512 and the Reader. The operating field of the reader is transformed on the ST25TV02K/512

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.

Frequency

The ISO 15693 standard defines the carrier frequency (fC) of the operating field as

13.56 MHz ± 7 kHz.

6.2

RF protocol description

6.2.1

Protocol description

The transmission protocol (or simply “the protocol”) defines the mechanism used to exchange instructions and

data between the VCD (Vicinity Coupling Device) and the VICC (Vicinity integrated circuit card) in both directions.

It is based on the concept of “VCD talks first”. The ST25TV02K/512 act as the VICC.

This means that a ST25TV02K/512 do not start transmitting unless it has received and properly decoded an

instruction sent by the VCD. The protocol is based on an exchange of:

•

a request from the VCD to the ST25TV02K/512,

•

a response from the ST25TV02K/512 to the VCD.

ST25TV02K ST25TV512

RF operations

DS12074 - Rev 11

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