XRT72L13 Datasheet, PDF (38/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
áç
PRELIMINARY
PIN DESCRIPTIONS
PIN #
160
NAME
TxOHInd/
TxPLClkEnb
TYPE
O
DESCRIPTION
Transmit Overhead Data Indicator/Transmit Payload Data Clock
Enable Output..
The funtion of this output pin depends upon whether the XRT72L13 is
operating in the “Clear-Channel” or the “High-Speed HDLC Control-
ler” Mode.
Clear Channel Framer Mode.
This output pin will pulse "high" one-bit period prior to the time that the
Transmit Section of the XRT72L13 will be processing an Overhead
bit. The purpose of this output pin is to warn the Terminal Equipment
that, during the very next bit-period, the XRT72L13 is going to be pro-
cessing an "Overhead" bit and will be ignoring any data that is applied
to the "TxSer" input pin.
NOTE: This output pin is only active if the XRT72L13 is operating in
the "Serial" Mode. This output pin will be pulled "low" if the device is
operating in the "Nibble-Parallel" Mode.
High Speed HDLC Controller Mode.
161
TxNibClk
O
Transmit Nibble Clock Signal
If the user opts to operate the XRT72L13 in the “Nibble-Parallel”
mode, then the XRT72L13 will derive this clock signal from either the
“TxInClk” or the “RxLineClk” signal (depending upon which signal is
selected as the timing reference).
The user is advised to configure the Terminal Equipment to output the
“outbound” payload data (to the XRT72L13 Framer IC) onto the
“TxNib[3:0]” input pins, upon the rising edge of this clock signal.
NOTES:
1. The XRT72L13 M13/Framer IC will output 1176 clock edges
(to the Terminal Equipment) for each “outbound” DS3 frame.
2. This pin is only active for “Clear-Channel Framer” applica-
tions.
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