The T5567 is a contactless R/W IDentification IC (IDIC) for applications in the 125KHz frequency range. 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 330-bit EEPROM (10 blocks, 33 bits each) can be read and written block-wise from a reader. Block 0 is reserved for setting the operation modes of the T5557 tag. Block 7 may contain password to prevent unauthorized writing. Data is transmitted from the IDIC 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 100% amplitude modulated (OOK) pulse interval encoded bit streams from the base station or reader.

The main features are:
- Contactless Read/Write Data Transmission
- Operating frequency: 100- 150KHz
- Small size, configurable for ISO11784/ 785 compatibility
- 330bit memory
- Dimension: CR80 (86mm*54mm*0.82mm)
- PVC or PET material, be available with offset printing, silk-screen printing
- Made into other shapes: keychain, tags, clamshell card, etc.