TP3406 DASL Digital Adapter for Subscriber LoopsGeneral Des criptionThe TP3406 is a complete monolithic transceiver for datatransmission on twisted pair subscriber loops. It is built onNational's double poly microCMOS process, and requiresonly a single a5 Volt supply. Alternate Mark Inversion (AMI)line coding, in which binary `1's are alternately transmittedas a positive pulse then a negative pulse, is used to ensurelow error rates in the presence of noise with lower emi radiationthan other codes such as Bi-phase (Manchester).Full-duplex transmission at 144 kb/s is achieved on a singletwisted wire pair using a burst-mode technique (Time CompressionMultiplexed). Thus the device operates as an ISDN`U' Interface for short loop applications, typically in a PBXenvironment, providing transmission for 2 B channels and 1D channel. On Ý24 cable, the range is up to 800 meters.System timing is based on a Master/Slave configuration,with the line card end being the Master which controls looptiming and synchronisation. All timing sequences necessaryfor loop activation and de-activation are generated on-chip.Selection of Master and Slave mode operation is programmedvia the Microwire Control Interface.A 2.048 MHz clock, which may be synchronized to the systemclock, controls all transmission-related timing functions.