2003AUG29_AMD_NTEK_MPR_ANCML MicrocircuitsCOMMUNICATION SEMICONDUCTORSApplication NoteCMX850 Communication Controller Reference Telephone Line interfaceAN/Telecom/850/1 August 2002Introduction The CMX850 Communications Controller IC is connected to a telephone line with a special interface circuit that is often referred to as a DAA (Data Access Arrangement). One of the main functions of the DAA is to provide a safety isolation barrier between the phone line and the low voltage circuits that users can touch. Recent changes to the regulatory requirements in Europe have allowed designers to reduce the cost of their DAA design without compromising performance. Here we describe two DAA circuits for the CMX850. The first circuit complies with the former European standard CTR 21. Since CTR 21 is no longer mandato……