XRT5997 Datasheet, PDF (25/37 Pages) Exar Corporation – Seven-Channel E1 Line Interface Unit

XRT5997
2.0 The Receive Section
The Receive Sections of the XRT5997 device consists
of the following blocks:
• The “Receive Equalizer” block
• The “Peak Detector” and “Slicer” block
• The “LOS Detector” block
• The “Receive Output Interface” block
2.1 Interfacing the Receive Sections to the Line
The design of each channel (within the XRT5997
device) permits the user to transformer-couple or
capacitive-couple the Receive Section to the line.
Additionally, as mentioned earlier, the specification
documents for E1 specify 75Ω termination loads, when
transmitting over coaxial cable, and 120Ω loads, when
transmitting over twisted-pair. Figures 7 , through 9
present the various methods that the user can employ
in order to interface the Receivers (of the XRT5997
device) to the line.
RxPOS_1
RxNEG_1
Loss of Signal - 1
U1
1
RxPOS_1
2
RxNEG_1
7
RTIP_1
R1
18.7
100
RxLOS_1
8
RRing_1
1 ^1:2 5
4
8
PE-65835
J1
BNC
1
XRT5997
Figure 7. Recommended Schematic for Interfacing the Receive Sections of the XRT5997
Device to the Line for 75Ω Applications (Transformer-Coupling)
Rev. 1.0.0
25