Evaluation Board

The XHFC-1SU Evaluation Board offers an immediate start of the development of your product. Different line interface subassemblies are available and must be piggypacked onto the XHFC-1SU Evaluation Board.

The XHFC-1SU Evaluation Board is made of the following functional parts:

  • the XHFC-1SU microchip
  • a socket to mount a line interface subassembly
  • a socket for a power feeding module (optional)
  • a connector to the host processor system
  • a PCM interface connector


Driver software plays an important role in all ISDN projects. This consideration leads to one of the basic principles of Cologne Chip: individual support for each project.
By having broad knowledge about ISDN applications, the support team of Cologne Chip will assist in finding the best approach regarding system architecture and concerning software aspects.

Linux drivers are available for all chips as open source software. Under the terms of GPL (GNU Public Licence) the source code of the Linux drivers may be used free of royalities.
Wheter a project is done as an in-house development or in cooperation with a design house as 3rd-party, Cologne Chip is committed to in-depth technical support for fast time-to-market.

Go to the official repository.

Transformer Selection Guide

Customers of Cologne Chip can choose from a variety of transformers. The relevant requirements for selecting the right transformer for each ISDN Interface are as follows:

Basic Rate (S/T)2-wire Basic Rate (Up0/UpN)

compatible to XHFC and HFC series

  1. Turns ratio of 1:2 (line side : chip side)
  2. Center tap on chip side (required for Cologne Chip receiver circuitry)

compatible to XHFC series

  1. Turns ratio of 1:1 (line side : chip side)
  2. Two separated windings (resp. a centre tap) on chip side (required for Cologne Chip receiver circuitry)

Several companies provide transformers and transformer modules that can be used with our ISDN Basic Rate and Primary Rate Interface controllers. Most popular are SMD modules with chokes for EMI reasons.