TP3406 DASL Digital Adapter for Subscriber Loops
General Description
The TP3406 is a complete monolithic transceiver for data
transmission on twisted pair subscriber loops. It is built on
National's double poly microCMOS process, and requires
only a single a5 Volt supply. Alternate Mark Inversion (AMI)
line coding, in which binary `1's are alternately transmitted
as a positive pulse then a negative pulse, is used to ensure
low error rates in the presence of noise with lower emi radiation
than other codes such as Bi-phase (Manchester).
Full-duplex transmission at 144 kb/s is achieved on a single
twisted wire pair using a burst-mode technique (Time Compression
Multiplexed). Thus the device operates as an ISDN
`U' Interface for short loop applications, typically in a PBX
environment, providing transmission for 2 B channels and 1
D channel. On Y24 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 loop
timing and synchronisation. All timing sequences necessary
for loop activation and de-activation are generated on-chip.
Selection of Master and Slave mode operation is programmed
via the Microwire Control Interface.
A 2.048 MHz clock, which may be synchronized to the system
clock, controls all transmission-related timing functions.