XRT72L13 Datasheet, PDF (324/370 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
TABLE 35: LISTING AND DESCRIPTION OF THE PIN ASSOCIATED WITH THE RECEIVE OVERHEAD DATA OUTPUT
INTERFACE" BLOCK
SIGNAL NAME TYPE
DESCRIPTION
RxOH
Output
Receive Overhead Data Output pin:
The XRT72L13 will output the overhead bits, within the incoming DS3 frames, via this pin.
The Receive Overhead Data Output Interface block will output a given overhead bit, upon the
falling edge of "RxOHClk". Hence, the external data link equipment should sample the data, at
this pin, upon the rising edge of "RxOHClk".
The XRT72L13 will always output the "DS3 Overhead" bits via this output pin. There are no
external input pins or register bit settings available that will disable this output pin.
RxOHClk
Output
Receive Overhead Data Output Interface Clock Signal:
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.
This clock signal is always active.
RxOHFrame
Output Receive Overhead Data Output Interface - Start of Frame Indicator:
The XRT72L13 will drive this output pin "high" (for one period of the "RxOHClk" signal); when-
ever the first overhead bit within a given DS3 frame is being driven onto the "RxOH" output pin.
Interfacing the “Receive Overhead Data Output
Interface” block to the Terminal Equipment (Meth-
od 1)
Figure 107 illustrates how one should interface the
“Receive Overhead Data Output Interface” block to
the Terminal Equipment; when using “Method 1” to
sample and process the overhead bits from the “in-
bound” DS3 data stream.
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