Keywords: T1, E1, T1/E1, single chip transceivers, SCT, framer, fractional, looped-timed, channel, port Related Parts
APPLICATION NOTE 309
Interfacing to the Fractional T1 and E1
May 04, 2001
Abstract: This application note provides an example fractional T1 and E1 circuit design using Dallas Semiconductor/Maxim Communications Products T1/E1 single chip transceivers (SCTs) and T1/E1 framers.
Introduction
This application note shows a "looped-timed" application where a Dallas framer or single-chip transceiver (SCT) is
configured for a fractional T1/E1 interface.
This application note applies to the following products:
T1 Framers
E1 Framers
T1 SCTS
E1 SCTS
T1/E1 SCTS
DS2141
DS2143
DS2151
DS2153
DS2156
DS21Q41
DS21Q43
DS2152
DS2154
DS2155
DS21Q42
DS21Q44
DS21352
DS21354
DS21Q55
DS21FF42
DS21FF44
DS21552
DS21554
DS21455
DS21FT42
DS21FT44
DS21Q552
DS21Q554
DS21458
DS21Q352
DS21Q354
DS36528
DS26524
DS26522
DS26521
DS26519
DS26518
General Configuration
It is common for a T1/E1 carrier subscriber to not have the full T1/E1 rate of service, but a fractional T1 or E1
service, since the full bandwidth may not be needed or affordable. The circuit shown in Figure 1 shows an example
of a fractional T1/E1 circuit design, where the application is "looped-timed" and connected to a V.35/RS-449/S530
interface. In this figure, the transmit and receive FT1/E1 streams occupy the same time slots. The DS2175 is our
T1/CEPT Elastic Store IC and the XR-T8000 is the Exar Clock Synchronizer/Adaptor for Communications IC. The
idle registers on the Dallas framer/SCT can be used to fill unused channels, and the used channels do not need to
be contiguous. RCHBLK can be used with TCHBLK to allow up to three additional FT1/E1 ports. Reset should be
activated after all the clocks are stable.
Figure 1. Fractional T1/E1 to V.35 interface.
Conclusion
This application note has shown how to design our framers/SCTs for fractional T1/E1 in a "loop-timed" application.
If you have further questions about fractional T1/E1, please contact the Telecommunication Applications support
team via email
or call 972-371-6555.
Dallas Framer/SCT Information
For more information about our framers/SCTs, please consult the data sheets available on our website at
www.maxim-ic.com/telecom.
