The ATA5577M233SC-DBB is a contactless read/write identification integrated chip (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 bidirectional communication interface. The antenna and chip together form a transponder or tag. The on-chip 363-bit EEPROM (11 blocks with 33 bits each) is read and written blockwise from a base station (reader). Data are 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 On-Off Keying (OOK) Pulse Interval Encoded (PIE) bit streams.