2

T5557

4517E–RFID–02/03

T5557 –

Building Blocks

Figure 2. Block Diagram

Analog Front End (AFE)

The AFE includes all circuits which are directly connected to the coil. It generates the

IC’s power supply and handles the bi-directional data communication with the reader. It

consists of the following blocks:

•

Rectifier to generate a DC supply voltage from the AC coil voltage

•

Clock extractor

•

Switchable load between Coil 1/Coil 2 for data transmission from tag to the reader

•

Field gap detector for data transmission from the base station to the tag

•

ESD protection circuitry

Data-rate Generator

The data rate is binary programmable to operate at any data rate between RF/2 and

RF/128 or equal to any of the fixed e5550/e5551 and T5554 bitrates (RF/8, RF/16,

RF/32, RF/40, RF/50, RF/64, RF/100 and RF/128).

Write Decoder

This function decodes the write gaps and verifies the validity of the data stream

according to the Atmel e555x write method (pulse interval encoding).

HV Generator

This on-chip charge pump circuit generates the high voltage required for programming

of the EEPROM.

DC Supply

Power is externally supplied to the IDIC via the two coil connections. The IC rectifies and

regulates this RF source and uses it to generate its supply voltage.

*

Coil 1

Coil 2

Modulator

POR

Input register

Memory

(330 bit EEPROM)

Controller

Test logic

Mode register

HV generator