The ATA5577 is a contactless read/write identification IC (IDIC®) for applications in the 125-kHz or 134-kHz frequency band. A single coil connected to the chip serves as the IC's power supply and bi-directional communication interface. The antenna and chip together form a transponder, or tag.
The on-chip 363-bit EEPROM (11 blocks with 33 bits each) can be read and written block-wise from a base station (reader). Two dedicated blocks are reserved for setting the IDIC operational modes. Another block may be used for a password to prevent unauthorized writing.
Data is transmitted from the IDIC (uplink) using load modulation. This is achieved by damping the RF field with a resistive load between the two terminals Coil 1 and Coil 2. The IC receives and decodes serial base station commands (downlink) which are encoded as 100% amplitude modulated (OOK) pulse-interval-encoded bit streams
