Rev. 3.5

RI-RFM-006A

Page 6 of 19

! Function and Operation

1. General

This RF-module IC counts on two operating modes:

Sending Mode - This mode is active when the “TXCT-“ pin is set to L-level. A remote TIRIS

transponder can be charged up and ID code can be sent to that transponder in this mode.

Receiving Mode - This mode is active when the “TXCT-“ pin is set to H-level. FSK signals sent from a

remote TIRIS transponder are received and demodulated in this mode.

Therefore, by switching over these modes using an external controller, data communications with a

TIRIS transponder can be made.

Note that this RF-module IC is exclusively designed to provide the user with a simple signal modulator-

demodulator (modem) function for data communications with a remote TIRIS transponder, based on the

appropriate data modulation-demodulation specifications. And therefore, it does not incorporate error

detection, data allotment nor other similar data processing functions in terms of protocol and data

formats.

(*) In both transmit and receive modes, this RF-module IC modulates and demodulates signals by logical

operation based on the incorporated master clock. This means that the modulating-demodulating

performance characteristics of this IC are directly affected by the frequency accuracy and variation of its

master clock (normal frequency is 17.1776 MHz). Therefore, the user is requested to select an oscillating

element or an external clock which is compatible with the remote TIRIS transponder to be used (see the

section describing the specifications “fexc”, “fL” and “fH”).

2. Sending Mode

In the Sending Mode, the frequency of the IC master clock (normal value: 17.1776 MHz) is divided

by 128. The resulting clock signal then has a frequency of 134.2 kHz (normal value). This resulting signal

is output as a composite signal for “TXHI” and “TXLO” terminals (pins) to drive the MOSFET which is

incorporated as an antenna resonance circuit driver, as illustrated below.

When the IC is in the Receiving Mode, its “TXHI” terminal is fixed at positive level and the “TXLO” at

high impedance. As a result, the output terminal “A” of the MOSFET used as an antenna resonance

circuit driver is fixed at negative level.

Note that when the IC is in the Sending Mode, its “RXDT-“ terminal is always fixed at positive level and

as a consequence, the IC’s FSK signal demodulator remains deactivated although data clock signals,

which are transmitted at a frequency resulting from division of the “A3IN” terminal signal frequency by

16, are output to the “RXCK”.

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RI45538NS

TXLO

TXHI

Master clock frequency divided by 128

(Ref. frequency, resulting: 134.2 kHz)

"A"

MOSFET(PCH)

MOSFET(NCH)