XRT72L53 Datasheet, PDF (130/467 Pages) Exar Corporation – THREE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

áç THREE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
PRELIMINARY
XRT72L53
REV. P1.1.7
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 is used to control the state of
the LLOOP[n] output pin of the Framer. 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’s, the state of the RLOOP and the LLOOP pins
are used to dictate which loop-back mode the LIU will
operate in. The following table presents the relation-
ship 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
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
modes, please consult the appropriate LIU IC 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 LLOOP[n]
output pin can be used for other purposes.
2.4.8.20 Line Interface Scan Register
LINE INTERFACE SCAN REGISTER (ADDRESS = 0X81)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
DMO
RLOL
RLOS
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
0
0
Bit 2 - DMO - (Drive Monitor Output)
This Read-Only bit-field indicates the logic state of
the DMO[n] input pin of the Framer. This input pin is
intended to be connected to the DMO output pin of an
Exar XRT73L0X-type of DS3/E3 LIU IC. If this bit-field
contains a logic "1", then the DMO input pin is "High".
An Exar XRT73L0X-type of DS3/E3 LIU IC will set
this pin "High" if the drive monitor circuitry (within the
LIU) has not detected any bipolar signals at the MTIP
and MRING inputs (of the LIU) within the last 128 +
32 bit periods.
Conversely, if this bit-field contains a logic "0", then
the DMO input pin is "High". The DS3/E3 LIU IC will
set this pin "Low" if bipolar signals are being detected
at the MTIP and MRING input pins.
As a consequence, the DMO output pin can be
thought of as a Transmit Driver Failure indicator.
NOTE: If this customer is not using an Exar XRT73L0X-type
of DS3/E3 LIU IC, then this input pin and bit-field can be
used for a variety of other purposes.
Bit 1 - RLOL - (Receive Loss of Lock)
This Read-Only bit-field indicates the logic state of
the RLOL[n] input pin of the Framer. This input pin is
intended to be connected to the RLOL output pin of
an Exar XRT73L0X-type of DS3/E3 LIU IC. If this bit-
field contains a logic "1", then the RLOL[n] input pin is
"High". An Exar XRT73L0X-type of DS3/E3 LIU IC
will set this pin "High" if the clock recovery phase-
locked-loop circuitry (within the LIU) has lost lock with
the incoming DS3/E3 data-stream and is not properly
recovering clock and data.
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