XRT72L13 Datasheet, PDF (154/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

XRT72L13 MULTIPLEXER/FRAMER IC
REV. 1.0.6
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PRELIMINARY
2. The user is advised to disabled the B3ZS/HDB3
encoder (within the XRT7300 IC) if the XRT72L13
is configured to operate in the B3ZS/HDB3 line
code.
3. If the customer is not using the XRT7300 DS3/E3/
STS-1 LIU IC, then he/she can use this bit-field and
the "Encodis" output pin for other purposes.
4. It is permissible to tie the "Encodis" output pin of
the XRT 72L13 DS3 Framer IC to both the "Enco-
dis" and "Decodis" input pins of the XRT7300.
Bit 2 - TxLev - (Transmit Output Line Build-Out
Select Output)
This "Read/Write" bit-field allows the user to control
the state of the "TxLev" output pin of the XRT72L13.
This output pin is intended to be connected to the Tx-
Lev input pin of the XRT7300 DS3/E3/STS-1 LIU IC.
If the user commands this signal to toggle "high", then
the XRT7300 DS3/E3/STS-1 LIU IC will disable the
"Transmit Line Build-Out" circuitry, and will transmit
unshaped (square-wave) pulses onto the line. If the
user commands this signal to toggle "low", then the
XRT7300 DS3/E3 LIU IC will enable the "Transmit
Line Build-Out" circuitry, and will transmit shaped
pulses onto the line.
In order to insure that the transmit output pulses of
the XRT7300 meet the "DSX-3 Isolated Pulse Tem-
plate Requirements (per Bellcore GR-499-CORE),
the user is advised to set this bit-field to "0", if the
length of cable (between the XRT7300 transmit out-
put and the DSX-3 Cross Connect System) is greater
than 225 feet.
Conversely, the user is advised to set this bit-field to
"1", if the length of cable (between the XRT7300
transmit output and the DSX-3 Cross Connect sys-
tem) 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".
Bit 1 - RLOOP - (Remote Loopback)
This "Read/Write" bit-field allows the user to control
the state of the RLOOP output pin of the XRT72L13
M13 device. This output pin is intended to be con-
nected to the "RLOOP" input pin of the XRT7300
DS3/E3 LIU IC.
In the XRT7300 DS3/E3 LIU IC, the state of the
"RLOOP" and the "LLOOP" pins are used to dictate
which loop-back mode the XRT7300 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
0
0
1
1
LLOOP
0
1
0
1
RESULTING LOOP-BACK MODE OF THE XRT7300
Normal Operation (No Loop-back Mode)
Analog Local Loop-back Mode
Remote Loop-back Mode
Digital Local Loop-back Mode
Writing a "1" into this bit-field commands the Framer
IC to toggle the "RLOOP" 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 of the XRT7300 DS3/E3
LIU's operation, during each of these above-men-
tioned loop-back modes, please consult the
"XRT7300 DS3/E3/STS-1 LIU IC" Data Sheet.
NOTE: If the customer is not using the XRT7300 DS3/E3/
STS-1 LIU IC, then he/she can use this bit-field and the
"RLOOP" output pin for other purposes.
Bit 0 - LLOOP - (Local Loop-back)
This "Read/Write" bit-field allows the user to control
the state of the LLOOP output pin of the XRT72L13
M13 device. This output pin is intended to be con-
nected to the LLOOP input pin of the XRT7300 DS3/
E3 LIU IC.
In the XRT7300 DS3/E3 LIU IC, the state of the
"RLOOP" and the "LLOOP" pins are used to dictate
which loop-back mode the XRT7300 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
0
0
1
LLOOP
0
1
0
RESULTING LOOP-BACK MODE OF THE XRT7300
Normal Operation (No Loop-back Mode)
Analog Local Loop-back Mode
Remote Loop-back Mode
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