XRT72L50 Datasheet, PDF (129/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
For a detailed description of the operation of a particular Exar XRT73L0X DS3/E3 LIU, while configured into
each of these above-mentioned loop-back modes, please consult the appropriate LIU IC Data Sheet.
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.
2.3.8.22 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
Not Used
DMO
RLOL
RLOS
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
1
1
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.
Conversely, if this bit-field contains a logic "0", then the RLOL input pin is "Low". The DS3/E3 LIU IC will hold
this pin "Low" as long as this clock recovery phase-locked-loop circuitry (within the LIU) is properly locked onto
the incoming DS3 or E3 data-stream, and is properly recovering clock and data from this data-stream.
NOTE: If the customer is not using an Exar XRT73L0X-type of DS3/E3/STS-1 IC, then this bit-field, and the RLOL[n] input
pin can be used for other purposes.
Bit 0 - RLOS - (Receive Loss of Signal)
This Read-Only bit-field indicates the logic state of the RLOS[n] input pin of the Framer. This input pin is
intended to be connected to the RLOS output pin of the DS3/E3 LIU IC. If this bit-field contains a logic "1", then
the RLOS[n] input pin is "High". The LIU will toggle this signal "High" if it (the LIU IC) is currently declaring an
LOS (Loss of Signal) condition.
Conversely, if this bit-field contains a logic "0", then the RLOS input pin is "Low". The LIU will hold this signal
"Low" if it is NOT currently declaring an LOS (Loss of Signal) condition.
NOTE: Asserting the RLOS input pin will cause the XRT72L50 Framer to generate the Change in LOS Condition interrupt
and declare an LOS (Loss of Signal) condition. Therefore, this input pin should not be used as a general purpose
input.
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