T555401N-DDW Atmel, T555401N-DDW Datasheet - Page 7

• Manufacturer Part Number: T555401N-DDW
• Manufacturer: Atmel

Specifications of T555401N-DDW

• Screening Level: Industrial
• Lead Free Status / Rohs Status: Supplier Unconfirmed

4. Operating the T5554
4.1
4.2
4.3
4.4
4.5
4576D–RFID–12/06
General
Supply
Read
Start-up
Read Data Stream
The basic functions of the T5554 are: supply IC from the coil, read data from the EEPROM to the
reader, write data into the IC and program these data into the EEPROM. Several errors can
be detected to protect the memory from being written with the wrong data (see
page
The T5554 is supplied via a tuned inductance (L 8 mH) which is connected to the Coil 1 and
Coil 2 pads. The incoming RF (actually a magnetic field) induces a current into the coil. The
on-chip rectifier generates the dc supply voltage (V
vents the IC from damage due to high-field strengths. Depending on the coil, the open-circuit
voltage across the LC circuit can reach more than 100V. The first occurrence of RF triggers a
power-on reset pulse, ensuring a defined start-up state.
Reading is the default mode after power-on reset. It is done by switching a load between the coil
pads on and off. This changes the current through the IC coil, which can be detected from the
reader unit.
The many different modes of the T5554 are activated after the first readout of block 0. The mod-
ulation is off while block 0 is read. After this set-up time of 256 field clock periods, modulation
with the selected mode starts.
Any field gap during this initialization will restart the complete sequence.
The first block transmitted is block 1. When the last block is reached, reading restarts with block
1. Block 0, which contains mode data, is normally never transmitted. However, the mode register
is continuously refreshed with the contents of EEPROM block 0.
Figure 4-1.
16).
Application Circuit
125 kHz
Reader coil
IAC
Energy
Data
Tuned LC
L~8 mH
DD
, V
SS
pads). Overvoltage protection pre-
210 pF
C
res
T5554
Figure 5-4 on
T5554
7