ST25DV04KC datasheet(77/203 Pages) STMICROELECTRONICS

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RF operations

Contactless exchanges are performed in RF mode as specified by ISO/IEC 15693 or NFC Forum Type 5.

The ST25DVxxKC 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 ST25DVxxKC load variation using Manchester coding with one or two

subcarrier frequencies at 423 kHz and 484 kHz. Data are transferred from the ST25DVxxKC at 6.6 kbit/s in low

data rate mode and 26 kbit/s in high data rate mode. The ST25DVxxKC supports the 53 kbit/s in high data rate

mode in one subcarrier frequency at 423 kHz.

The ST25DVxxKC 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 ST25DVxxKC 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 ST25DVxxKC by the RF operating field of the reader,

•

transmission of a command by the reader (ST25DVxxKC detects carrier amplitude modulation)

•

transmission of a response by the ST25DVxxKC (ST25DVxxKC modulates is load clocked at subcarrier

rate)

Operating field

The ST25DVxxKC operates continuously between the minimum and maximum values of the electromagnetic field

H defined in Table 256. RF characteristics. The Reader has to generate a field within these limits.

Power transfer

Power is transferred to the ST25DVxxKC by radio frequency at 13.56 MHz via coupling antennas in the

ST25DVxxKC and the Reader. The RF operating field of the reader is transformed on the ST25DVxxKC 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.

7.2

RF communication and energy harvesting

As the current consumption can affect the AC signal delivered by the antenna, RF communications with

ST25DVxxKC are not guaranteed during voltage delivery on the energy harvesting analog output V_EH.

7.3

Fast transfer mode mailbox access in RF

Thanks to dedicated commands, the RF interface has the possibility to check Mailbox availability, and the

capability to access it directly to put or get a message from it (see Section 5.1 Fast transfer mode (FTM) for

specific features).

ST25DV04KC ST25DV16KC ST25DV64KC

RF operations

DS13519 - Rev 3

page 77/203

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