XRT59L91 Datasheet, PDF (14/28 Pages) Exar Corporation – Single-Chip E1 Line Interface Unit

XRT59L91
Preliminary
2.0 The Receive Section
The Receive Section of the XRT59L91 device consists
of the following blocks:
l The “Receive Equalizer” block
l The “Peak Detector” and “Slicer” block
l The “LOS Detector” block
l The “Receive Output Interface” block
2.1 Interfacing the Receive Section to the Line
The design of the XRT59L91 device permits the user
to transformer-couple or capacitive-couple the Re-
ceive Section to the line. Additionally, as mentioned
earlier, the specification documents for E1 specify
75W termination loads, when transmitting over coaxial
cable, and 120W loads, when transmitting over twisted-
pair. Figures 7 through 9 present the various methods
that the user can employ in order to interface the
Receiver (of the XRT59L91 device) to the line.
R xP O S
RxNEG
Loss of Signal
U1
6 _RxPOS
7 _RxNEG
8 _RxLOS
9
R T IP
10
R R in g
RL
18.7
1 ^1:2 5
4
8
PE-65835
J1
BNC
1
XRT59L91
Figure 7. Recommended Schematic for Interfacing the Receive Section of the XRT59L91
Device to the Line for 75W Applications (Transformer-Coupling)
Rev. P2.00
14