XRT82D20_06 Datasheet, PDF (17/27 Pages) Exar Corporation – SINGLE CHANNEL E1 LINE INTERFACE UNIT

REV. 1.0.8
XRT82D20
SINGLE CHANNEL E1 LINE INTERFACE UNIT
FIGURE 11. ILLUSTRATION OF HOW TO INTERFACE THE XRT82D20 TO THE LINE FOR 120 OHM APPLICATIONS AND
3.3V OPERATION ONLY
120 Ω Twisted Pair
1:2
120 Ω
Signal
Source
120 Ω Twisted Pair
2:1
R Load
120 Ω
866 Ω
866 Ω
RTIP
Rx Input
RRING
9.1 Ω
9.1 Ω
TTIP
Tx Output
TRING
RPOS/RData
RNEG/LCV
RClk
TVDD
AVDD
10 µF
TxLEV
TGND
AGND
+3.3 V
0.1 µF
TNEG/CODE
TPOS/TData
TClk
NOTES:
1. Figure 10 and Figure 11indicate that for 3.3 V operation, both 75 Ω and 120 Ω applications, the user should
connect a 9.1Ω resistor in series between the TTIP/TRing outputs and the transformer.
2. Figure 10 and Figure 11indicate that the user should use a 2 : 1 STEP-UP Transformer.
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