The CT25208 Digital IP core is a standard Clause 4 CSMA/CD MAC exposing a proprietary, FIFO-like MAC Client interface (TX/RX).
On the other end, the CT25208 features a proprietary, MII-like Reconciliation Sublayer (RS) interface, including adapter modules to interface with standard MII/RMII PHYs.
The RTL code is written in plain Verilog 2005 HDL, and it is fully synthesizable on standard cells and FPGA systems.

The flexible MAC Client interface can also be configured for transferring 1, 2, or 4 bytes at a time, supporting both little-endian and big-endian byte order. This feature allows the CT25208 IP to be used with many MCUs and other systems based on shared-memory access by means of a dedicated Bus Adapted interface.
The CT25208 can be used in conjunction with other analog and digital blocks like (a) the CT25205 to implement a digital 10BASE-T1S MACPHY and (b) the CT25203, the CT25205 and the CT25209 to implement a complete OPEN Alliance MACPHY.


  • Full CSMA/CD compliance, including half and full-duplex
  • Support for 10 and 100 Mb/s operation
  • Single MAC address filtering
  • Promiscuous Mode
  • FCS add/check
  • Diagnostic Counters
  • Status reporting
  • Multiple MAC address filtering (multicast) based on address/mask pairs
  • Broadcast / Multicast filtering
  • Configurable FCS checking
  • Underrun/Overrun error handling
  • Disable of back-off mechanism


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