XR72L52 Datasheet, PDF (36/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L52
REV. 1.0.1
PIN DESCRIPTION
PIN #
155
PIN NAME
RLOOP[0]
156
LLOOP[0]
157
Req[0]
158
TAOS[0]
xr
TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
TYPE
DESCRIPTION
O Remote Loopback Output Pin (to the XRT73L0x DS3/E3 Line Interface Unit
IC):
This output pin is intended to be connected to the RLOOP input pin of the
XRT73L0x DS3/E3 Line Interface Unit IC. The user can command this signal to
toggle "High" and force the XRT73L0x DS3/E3 Line Interface Unit IC into the
Remote Loopback mode. Commanding this signal to toggle "Low" allows the
XRT73L0x to operate in the normal mode.
For a detailed description of the XRT73L0x DS3/E3 Line Interface Unit IC's
operation during Remote Loopback, please see the XRT73L0x DS3/STS-1/ E3
Line Interface Unit IC's Data Sheet.
If the XRT73L0x DS3/E3 Line Interface Unit IC is not used, this output pin may
be used for other purposes.
O Local Loopback Output Pin (to the XRT73L0x DS3/E3 Line Interface Unit
IC):
This output pin is intended to be connected to the LLOOP input pin of the
XRT73L0x LIU IC. The user can command this signal to toggle "High" and force
the LIU into the Local Loopback mode.
For a detailed description of the XRT73L0x DS3/E3 Line Interface Unit IC's
operation during Local Loopback, please see the XRT73L0x DS3/STS-1/E3
Line Interface Unit IC's Data Sheet.
If the XRT73L0x DS3/E3 Line Interface Unit IC is not used, this output pin may
be used for other purposes.
O Receive Equalization Enable/Disable Select output pin - (to be connected
to the XRT73L0x DS3/E3 Line Interface Unit IC):
This output pin is intended to be connected to the REQ input pin of the
XRT73L0x DS3/E3 (REQDIS or REQEN of the XRT73L03 or XRT 73L04) Line
Interface Unit IC. The user can control the state of this output pin by writing a '0'
or '1' to Bit 5 (REQ) within the Line Interface Driver Register (Address = 0x80). If
the user commands this signal to toggle "High" then the internal Receive Equal-
izer within the XRT73L0x is disabled. If this output signal is toggled "Low", then
the internal Receive Equalizer within the XRT73L0x is enabled.
For information on the criteria that should be used when deciding whether to
bypass the equalization circuitry or not, please consult the XRT73L0x DS3/E3
Line Interface Unit data sheet.
NOTE: If the XRT73L0x DS3/E3 Line Interface Unit IC is not used, this output
pin may be used for other purposes.
O Transmit All Ones Signal (TAOS) Command (for the XRT73L0x Line Inter-
face Unit IC):
This output pin is intended to be connected to the TAOS input pin of the
XRT73L0x DS3/E3 Line Interface Unit IC. The user can control the state of this
output pin by writing a '0' or '1' to Bit 4 (TAOS) of the Line Interface Drive Regis-
ter (Address = 0x80). If the user commands this signal to toggle "High" then it
will force the XRT73L0x Line Interface Unit IC to transmit an All Ones pattern
onto the line. If the user commands this output signal to toggle "Low" then the
XRT73L0x DS3/E3 Line Interface Unit IC will proceed to transmit data based
upon the pattern that it receives via the TxPOS and TxNEG output pins.
NOTE: If the XRT73L0x DS3/E3 Line Interface Unit IC is not used, this output
pin may be used for other purposes.
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