XRT72L13 Datasheet, PDF (46/370 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 #
190
NAME
RxPOS
191
RxNEG
192
RxOH
193
RxOHEnable
194
RxOHClk
195
RxOHFrame
196
RxLOS
TYPE
I
I
O
O
O
O
O
DESCRIPTION
Receive Positive Data Input:
The exact role of this input pin depends upon whether the Framer is
operating in the Unipolar or Bipolar Mode.
Unipolar Mode:
This input pin functions as the "Single-Rail" input for the "incoming"
DS3 data stream. The signal at this input pin will be sampled and
latched (into the Receive Framer block) on the "user-selected" edge
of the RxLineClk signal.
Bipolar Mode:
This input functions as one of the dual rail inputs for the incoming
AMI/B3ZS encoded DS3 data that has been received from an exter-
nal Line Interface Unit (LIU) IC. RxNEG functions as the other dual
rail input for the Framer. When this input pin is asserted, it means that
the LIU has received a "positive polarity" pulse from the line.
Receive Negative Data Input:
The exact role of this input pin depends upon whether the Framer is
operating in the Unipolar or Bipolar Mode.
Unipolar Mode:
This input pin is inactive, and should be pulled ("low" or "high") when
the Framer is operating in the Unipolar Mode.
Bipolar Mode:
This input pin functions as one of the dual rail inputs for the incoming
AMI/B3ZS encoded DS3 data that has been received from an exter-
nal Line Interface Unit (LIU) IC. RxPOS functions as the other dual
rail input for the Framer. When this input pin is asserted, it means that
the LIU has received a "negative polarity" pulse from the line.
Receive Overhead Output Port:
All overhead bits, which are received via the "Receive Section" of the
Framer IC; will be output via this output pin, upon the rising edge of
RxOHClk.
Receive Overhead Enable Indicator:
The XRT72L13 will assert this output signal for one “RxOutClk” period
when it is safe for the Terminal Equipment to sample the data on the
“RxOH” output pin.
Receive Overhead Clock:
The XRT72L13 will output the Overhead bits (within the incoming DS3
frames), via the "RxOH" output pin, upon the falling edge of this clock
signal.
As a consequence, the "user's data link equipment" should use the
rising edge of this clock signal to sample the data on both the "RxOH"
and "RxOHFrame" output pins.
NOTE: This clock signal is always active.
Receive Overhead Frame Boundary Indicator:
This output pin pulses "high" whenever the Receive Overhead Data
Output Interface outputs the first overhead bit (or nibble) of a new DS3
frame.
Receive Section - Loss of Signal Output Indicator:
This pin is asserted when the Receive Section encounters a string of
180 consecutive 0's via the RxPOS and RxNEG pins.
This pin will be negated once the Receive Section has detected at
least 60 pulses within 180 bit-periods.
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