Instruction Manual

DS26503 T1/E1/J1 BITS Element
77 of 123
13. LINE INTERFACE UNIT (LIU)
The LIU in the DS26503 contains three sections: the receiver, which handles clock and data recovery; the
transmitter, which waveshapes and drives the network line; and the jitter attenuator. These three sections
are controlled by the line interface control registers (LIC1–LIC4), which are described below.
The DS26503 can switch between T1 or E1 networks without changing any external components on
either the transmit or receive side. Figure 13-1 shows a network connection using minimal components.
In this configuration the DS26503, using a fixed 120Ω external termination, can connect to T1, J1, E1, or
6312K without any component change. The receiver can adjust the 120Ω termination to 100Ω, 110Ω or
75Ω. The transmitter can adjust its output impedance to provide high return loss characteristics for 75Ω,
100Ω, 110Ω, and 120Ω lines. Other components may be added to this configuration to meet safety and
network protection requirements. This is covered in the Recommended Circuits section.
Figure 13-1. Basic Network Connection
TTIP
TRING
RTIP
RRING
DS26503
TRANSMIT
LINE
RECEIVE
LINE
10
m
F
60 60
0.01mF
BACKPLANE
CONNECTIONS
1:1
2:1