23 mm Transponder Reference Manual
25 July 1996
Page 4 of 22
1. Introduction
The TIRIS 23 mm Glass Encapsulated Pulsed FM Transponder is a key product in low frequency
RFID systems that can be used for a variety of applications, such as automotive security systems.
The device is available in Read Only (RO) and Read/Write (R/W) versions. Electro Magnetic
signals are used to power the passive (batteryless) device, to transmit the identification number to
a reader unit or to program the device with new data. The basic principle is described in Figure 1.
Both RO and R/W versions use an 80 bit non-volatile memory (EEPROM) for storage of 64
identification bits and a 16 bit Block Check Character (BCC). The RO type is factory
programmed with a unique tamperproof code that cannot be altered. The R/W version can be
programmed by the user.
The 23 mm Transponder comprises a ferrite core antenna, a charge capacitor, a resonance
capacitor and the integrated circuit (Figure 2). The antenna inductance and the resonance
capacitor form a high quality resonant circuit.
CF45538
RF MODULE
FIELD LINES
CONTROL
UNIT
TIRIS READ/WRITE UNIT
ANTENNA AXIS
TRANSMIT/RECEIVE ANTENNA
TRANSPONDER
Figure 1: System Configuration Showing the Reader, Antenna and Transponder
CHARGE
CAPACITOR
ANTENNA
TRANSPONDER
IC
Figure 2: Block Diagram of the TIRIS Pulsed FM Transponder
