XRT72L13 Datasheet, PDF (40/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
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PRELIMINARY
PIN DESCRIPTIONS
PIN #
167
NAME
TxOHIns
168
TxAISEn
169
TxOHFrame
170
TxOHEnable
TYPE
I
I
O
O
DESCRIPTION
Transmit Overhead Data Insert Input.
Asserting this input signal (e.g., setting it "high") enables the Transmit
Overhead Data Input Interface to accept "overhead" data from the
Terminal Equipment. In other words, while this input pin is "high", the
Transmit Overhead Data Input Interface will sample the data at the
"TxOH" input pin, on the falling edge of the "TxOHClk" output signal.
Conversely, setting this pin "low" configures the "Transmit Overhead
Data Input Interface" to NOT sample (e.g., ignore) the data at the
"TxOH" input pin, on the falling edge of the "TxOHClk" output signal.
NOTES:
1. If the Terminal Equipment attempts to insert an overhead bit
that cannot be accepted by the "Transmit Overhead Data
Input Interface" (e.g., if the Terminal Equipment asserts the
"TxOHIns" signal, at a time when one of these "non-insert-
able" overhead bits are being processed); that particular
insertion effort will be ignored.
2. This pin is only used in “Clear-Channel Framer” applications.
Transmit AIS Command Input:
Setting this input pin "high" configures the XRT72L13 to transmit an
AIS (Alarm Indication Signal) pattern to the remote terminal.
Setting this input pin “low” configures the Transmit Section to generate
DS3 traffic in a normal manner.
Transmit Overhead Frame:
This output pin pulses "high" when the Transmit Overhead Data Input
Interface block is expecting the first Overhead bit, within a DS3 frame
to be applied to the TxOH input pin.
This pin is "high" for one clock period of TxOHClk.
Transmit Overhead Frame Enable:
The XRT72L13 will assert this signal, for one “TxInClk” period, just
prior to the instant that the “Transmit Overhead Data Input Interface”
will be sampling and processing an overhead bit.
If the Terminal Equipment intends to insert its own value for an over-
head bit, into the outbound DS3 frame, it is expected to sample the
state of this signal, upon the falling edge of “TxInClk”. Upon sampling
the “TxOHEnable” high, the Terminal Equipment should (1) place the
desired value of the overhead bit, onto the “TxOH” input pin and (2)
assert the “TxOHIns” input pin. The Transmit Overhead Data Input
Interface” block will sample and latch the data on the “TxOH” signal,
upon the rising edge of the very next “TxInClk” input signal.
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