XRT72L56 Datasheet, PDF (148/486 Pages) Exar Corporation – SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L56 SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.2
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PRELIMINARY
Conversely, the user is advised to set this bit-field to
"1", if the length of cable (between the LIU transmit
output and the DSX-3 Cross Connect system) is less
than 225 feet.
Writing a "1" to this bit-field commands the Framer to
toggle the TxLev output "High". Writing a "0" to this
bit-field commands the Framer to toggle this output
signal "Low".
NOTES:
1. The TxLEV function is only applicable to DS3 appli-
cations. E3 LIUs do not support this kind of Line
Build out feature.
2. If the customer is not using an Exar XRT73L0X
DS3/E3 LIU IC, then this bit-field and the TxLev
output pin can be used for other purposes.
Bit 1 - RLOOP - (Remote Loopback)
This Read/Write bit-field permits the user to control
the state of the RLOOP[n] output pin of the Framer
device. This output pin is intended to be connected to
the RLOOP input pin of the DS3/E3 LIU IC.
When using Exar’s family of XRT73L0X DS3/E3 LIU
devices, the state of the RLOOP and the LLOOP pins
are used to dictate which loop-back mode the LIU de-
vice will operate in. The following table presents the
relationship between the state of these two input pins
(or bit-fields) and the resulting loop-back modes.
RLOOP
LLOOP
RESULTING LOOP-BACK MODE OF THE DS3/E3 LIU DEVICE
0
0
Normal Operation (No Loop-back Mode)
0
1
Analog Local Loop-back Mode
1
0
Remote Loop-back Mode
1
1
Digital Local Loop-back Mode
Writing a "1" into this bit-field commands the Framer
IC to toggle the RLOOP[n] output signal "High". Writ-
ing a "0" into this bit-field commands the Framer IC to
toggle this output signal "Low".
For a detailed description on the operation of a partic-
ular “Exar XRT73L0X” DS3/E3 LIU, while configured
into each of these above-mentioned loop-back
modes, please consult the appropriate LIU Data
Sheet.
Currently the following “XRT73L0X Family of DS3/E3/
STS-1 LIU IC Data Sheets are now available:
• XRT7300 1-Channel DS3/E3/STS-1 LIU IC (5V)
• XRT73L00 1-Channel DS3/E3/STS-1 LIU IC (3.3V)
• XRT7302 2-Channel DS3/E3/STS-1 LIU IC (5V)
• XRT73L03 3-Channel DS3/E3/STS-1 LIU IC (3.3V)
• XRT73L04 4-Channel DS3/E3/STS-1 LIU IC (3.3V)
•
NOTE: If the customer is not using an Exar XRT73L0X
DS3/E3/STS-1 LIU IC, then this bit-field and the RLOOP[n]
output pin can be used for other purposes.
Bit 0 - LLOOP - (Local Loop-back)
This Read/Write bit-field permits the user to control
the state of the LLOOP[n] output pin of the Framer
device. This output pin is intended to be connected to
the LLOOP input pin of the DS3/E3 LIU IC.
When using Exar’s family of XRT73L0X DS3/E3 LIU
devices, the state of the RLOOP and the LLOOP pins
are used to dictate which loop-back mode the LIU de-
vice will operate in. The following table presents the
relationship between the state of these two input pins
(or bit-fields) and the resulting loop-back modes.
RLOOP
LLOOP
RESULTING LOOP-BACK MODE OF THE DS3/E3 LIU DEVICE
0
0
Normal Operation (No Loop-back Mode)
0
1
Analog Local Loop-back Mode
1
0
Remote Loop-back Mode
1
1
Digital Local Loop-back Mode
Writing a "1" into this bit-field commands the Framer
to toggle the LLOOP[n] output signal "High". Writing
a "0" into this bit-field commands the Framer to toggle
this output signal "Low".
For a detailed description of the operation of a partic-
ular “Exar XRT73L0X” DS3/E3 LIU, while configured
into each of these above-mentioned loop-back
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