XRT72L13 Datasheet, PDF (67/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

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PRELIMINARY
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC XRT72L13
REV. 1.0.6
FIGURE 26. FUNCTIONAL BLOCK DIAGRAM OF THE XRT72L13 M13 MULTIPLEXER/FRAMER IC, WHILE OPERATING
IN THE "MULTIPLEXER/DE-MULTIPLEXER MODE
TxPOS
TxNEG
TxLineClk
RxPOS
RxNEG
RxLineClk
CCleleaarrCChhaannnneel _l
DDSS33FFrraammeerr
32/64 Bit
De-Jitter
FIFO
MMicicrroopprroocceessssoorr
IInnteterrfafaccee
M23
MUX
M12
MUX
DS2 or G.747
Data Streams
M23
DEMUX
M12
DEMUX
TxDS1[0: 27]
TxClk[0:27]
RxDS1[0: 27]
RxClk[0:27]
When the XRT72L13 has been configured to operate
in the "Multiplexer/De-Multiplexer Mode, then the chip
will function as follows.
1.1.1 In the Transmit Direction
When the XRT72L13 is operating the "Multiplexer/De-
Multiplexer" Mode, it consist of the following blocks.
• Seven (7) M12 MUXes.
• An M23 MUX.
• The Clear Channel DS3 Framer Block.
1.1.1.1 Operation of the M12 MUX
Each M12 MUX can be configured to accept either 4
DS1 signals, 3 E1 signals or a DS2 signal. Whenever
a given M12 MUX is configured to operate in the
“DS1” Mode, then it will accept four (4) DS1 signals
(via the “TxDS1Data_n” input pins) and it will multi-
plex these DS1 signals into a DS2 signal.
Whenever a given M12 MUX is configured to operate
in the “ITU-T G.747” Mode, then it will accept three
(3) E1 signals (via 3 out of 4 of the “TxDS1_n” input
pins) and it will multiplex these E1 signals into an
“ITU-T G.747” signal.
Finally, whenever a given M12 MUX is configured to
operate in the “DS2 Pass-Thru” Mode, then it will ac-
cept a DS2 signal (via one of the “TxDS1Data_n” in-
put pins) and will route these signals to the M23
MUX.
Each M12 MUX also consists of a “Transmit DS2” or
“ITU-T G.747 Framer” block. As the M12 MUX out-
puts its DS2 or ITU-T G.747 data stream to the “M23
MUX” then the “Transmit DS2/G.747 Framer” block
will do the following.
• Encapsulate the composite data stream (derived
from 4 DS1 signals) into an outbound DS2 framing
structure.
• Set the “Cxx” bits to the appropriate values in order
to indicate whether or not a bit-stuff event occurred
when creating this particular DS2 frame.
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