XRT86L30
REV. 1.0.1
SINGLE T1/E1/J1 FRAMER/LIU COMBO
4.0 GENERAL DESCRIPTION AND INTERFACE
The XRT86L30 supports multiple interfaces for various modes of operation. The purpose of this section is to
present a general overview of the common interfaces and their connection diagrams. Each mode will be
described in full detail in later sections of the datasheet.
NOTE: For a brief tutorial on Framing Formats, see Appendix A in the back of the datasheet.
4.1
Physical Interface
The Line Interface Unit generates/receives standard return-to-zero (RZ) signals to the line interface for T1/E1/
J1 twisted pair or E1 coaxial cable. The physical interface is optimized by placing the terminating impedance
inside the LIU. This allows one bill of materials for all modes of operation reducing the number of external
components necessary in system design. The transmitter outputs only require one DC blocking capacitor of
0.68µF and a 1:2 step-up transformer. The receive path inputs only require one bypass capacitor of 0.1µF
connected to the center tap (CT) of the transformer and a 1:1 transformer. The receive CT bypass capacitor is
required for Long Haul Applications, and recommended for Short Haul Applications. Figure 7 shows the
typical connection diagram for the LIU transmitters. Figure 8 shows a typical connection diagram for the LIU
receivers.
F
IGURE 7. LIU TRANSMIT
C
ONNECTION
D
IAGRAM
U
SING
INTERNAL TERMINATION
XRT86L30 LIU
TTIP
1:2
C=0.68uF
Transmitter
Output
Line Interface T1/E1/J1
TRING
One Bill of Materials
Internal Impedance
F
IGURE 8. LIU RECEIVE CONNECTION DIAGRAM USING INTERNAL TERMINATION
XRT86L30 LIU
RTIP
1:1
Receiver
Input
Line Interface T1/E1/J1
RRING
0.1µF
One Bill of Materials
Internal Impedance
144
EXAR [ EXAR CORPORATION ]
