XRT72L13 Datasheet, PDF (41/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

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PRELIMINARY
PIN DESCRIPTIONS
PIN #
NAME
171
TxOHClk
172
TxOH
173
TxNEG
174
TxPOS
XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
TYPE
O
O
O
O
DESCRIPTION
Transmit Overhead Clock
This output signal serves two purposes:
1. The Transmit Overhead Data Input Interface block will provide a
rising clock edge on this signal, one bit-period prior to the start to the
instant that the “Transmit Overhead Data Input Interface” block is pro-
cessing an overhead bit.
2. The Transmit Overhead Data Input Interface will sample the data at
the “TxOH” input pin, on the falling edge of this clock signal (provided
that the “TxOHIns” input pin is “HIGH”).
NOTE: The Transmit Overhead Data Input Interface block will supply a
clock edge for all overhead bits within the DS3 frame (via the “TxO-
HClk” output signal). This includes those overhead bits that the
“Transmit Overhead Data Input Interface” will not accept from the Ter-
minal Equipment.
Transmit Overhead Input Pin
The Transmit Overhead Data Input Interface accepts the overhead
data via this input pin, and inserts into the "overhead" bit position
within the very next "outbound" DS3 frame. If the "TxOHIns" pin is
pulled "high", the Transmit Overhead Data Input Interface will sample
the data at this input pin (TxOH), on the falling edge of the "TxOHClk"
output pin. Conversely, if the "TxOHIns" pin is pulled "low", then the
Transmit Overhead Data Input Interface will NOT sample the data at
this input pin (TxOH). Consequently, this data will be ignored
Transmit Negative Polarity Pulse:
The exact role of this output pin depends upon whether the Framer is
operating in the Unipolar or Bipolar Mode.
Unipolar Mode:
This output signal pulses "high" for one bit period, at the end of each
"outbound" DS3 frame. This output signal is at a logic "low" for all of
the remaining bit-periods of the "outbound" DS3 frames
Bipolar Mode:
This output pin functions as one of the two dual-rail output signals that
commands the sequence of pulses to be driven on the line. TxPOS is
the other output pin. This input is typically connected to the TNData
input of the external DS3/E3 Line Interface Unit IC. When this output
is asserted, it will command the LIU to generate a negative polarity
pulse on the line.
Transmit Positive Polarity Pulse:
The exact role of this output pin depends upon whether the Framer is
operating in the Unipolar or Bipolar Mode.
Unipolar Mode:
This output pin functions as the "Single-Rail" output signal for the
"outbound" DS3 data stream. The signal, at this output pin, will be
updated on the "user-selected" edge of the TxLineClk signal.
Bipolar Mode:
This output pin functions as one of the two dual rail output signals that
commands the sequence of pulses to be driven on the line. TxNEG is
the other output pin. This input is typically connected to the TPData
input of the external DS3 or E3 Line Interface Unit IC. When this out-
put is asserted, it will command the LIU to generate a positive polarity
pulse on the line.
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