XRT72L13 Datasheet, PDF (43/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

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PRELIMINARY
PIN DESCRIPTIONS
PIN #
NAME
179
ENCODIS
180
TxLEV
XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
TYPE
O
O
DESCRIPTION
Encoder (HDB3) Disable Output pin (intended to be connected to
the XRT7300 DS3/E3 Line Interface Unit IC).
This output pin is intended to be connected to the Encodis input pin of
the XRT7300 DS3/E3 Line Interface Unit IC. The user can control the
state of this output pin by writing a "0" or "1" to Bit 3 (Encodis) within
the Line Interface Driver Register (Address = 0x80). If the user com-
mands this signal to toggle "high" then it will disable the B3ZS
encoder circuitry within the XRT7300 IC. Conversely, if the user com-
mands this output signal to toggle "low", then the B3ZS Encoder cir-
cuitry, within the XRT7300 IC will be enabled.
Writing a "1" to Bit 3 of the Line Interface Driver Register (Address =
0x80) will cause this output pin to toggle "high". Writing a "0" to this
bit-field will cause this output pin to toggle "low".
NOTES:
1. The user is advised to disable the B3ZS encoder (within the
XRT7300 IC) if the XRT72L13 M13 Multiplexer/Framer IC has
been configured to operate in the B3ZS/HDB3 line code.
2. If the customer is not using the XRT7300 DS3/E3 Line Inter-
face Unit IC, then this output pin can be used for a variety of
other purposes.
Transmit Line Build-Out Enable/Disable Select Output (to be con-
nected to the XRT7300 DS3/E3 Line Interface Unit IC).
This output pin is intended to be connected to the TxLev input pin of
the XRT7300 DS3/E3 Line Interface Unit IC. The user can control the
state of this output pin by writing a "0" or a "1" to Bit 2 (TxLev) within
the Line Interface Driver Register (Address = 0x80).
Writing a "1" to Bit 2 of the Line Interface Drive Register (Address =
0x80) will cause this output pin to toggle "high". Writing a "0" to this
bit-field will cause this output pin to toggle "low".
If the user commands this signal to toggle "high" then the "Transmit
Line Build-Out" circuit (within the XRT7300) will be disabled. In this
mode, the XRT7300 will output unshaped (e.g., square) pulses onto
the line (via the TTIP and TRING output pins).
Conversely, if the user commands this signal to toggle "low" then the
"Transmit Line Build-Out" circuit (within the XRT7300) will be disabled.
In this mode, the XRT7300 will output shaped (e.g., more rounded)
pulses onto the line (via the TTIP and TRING output pins).
In order to comply with the "DSX-3 Isolated Pulse Template Require-
ment" (per Bellcore GR-499-CORE), the user is advised to command
this output pin to be "high" if the cable length (between the transmit
output of the XRT7300 and the DSX-3 Cross Connect System) is
greater than 225 feet. Conversely, the user is advised to command
this output pin to be "low" if the cable length (between the transmit
output of the XRT7300 and the DSX-3 Cross Connect System) is less
than 225 feet.
NOTE: This output pin can be used for a variety of other purposes if
the XRT7300 DS3/E3 LIU is not used.
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