XRT82D20_06 Datasheet, PDF (16/27 Pages) Exar Corporation – SINGLE CHANNEL E1 LINE INTERFACE UNIT

XRT82D20
SINGLE CHANNEL E1 LINE INTERFACE UNIT
REV. 1.0.8
1.4 Interfacing the Transmit Section of the XRT82D20 to the Line
ITU-T G.703 specifies that the E1 line signal can be transmitted over coaxial cable and terminated with 75Ω or
transmitted over twisted-pair and terminated with 120Ω.
In both applications (e.g., 75Ω or 120Ω, the user is advised to interface the Transmitter to the Line, in the
manner as depicted in Figure 10 and Figure 11, respectively.
FIGURE 10. ILLUSTRATION OF HOW TO INTERFACE THE XRT82D20 TO THE LINE FOR 75 OHM APPLICATIONS AND
3.3V OPERATION ONLY
75 Ω Coax
75 Ω
Signal
Source
75 Ω Coax
R Load
75 Ω
1:2
2:1
270 Ω
RTIP
Rxx Input
270 Ω
RRING
9.1 Ω
9.1 Ω
TTIP
Tx Output
TRING
RPOS/RData
RNEG/LCV
RClk
TVDD
AVDD
10µF
TxLEV
TGND
AGND
+3.3 V
0.1 µF
TNEG/CODE
TPOS/TData
TClk
15