XRT72L13 Datasheet, PDF (259/370 Pages) Exar Corporation – M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC

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PRELIMINARY
XRT72L13
M13 MULTIPLEXER/CLEAR CHANNEL DS3 FRAMER IC
REV. P1.0.6
FIGURE 72. BEHAVIOR OF THE "TERMINAL INTERFACE" SIGNALS BETWEEN THE XRT72L13 AND THE TERMINAL
EQUIPMENT (DS3 MODE 5 OPERATION)
Terminal Equipment Signals
TxInClk
DS3_Nib_Clock_In
DS3_Data_Out[3:0] Nibble [1175]
Tx_Start_of_Frame
Nibble [0]
XRT72L13 Transmit Payload Data I/F Signals
TxInClk
TxNibClk
TxNib[3:0]
Nibble [1175]
TxFrameRef
Nibble [0]
DS3 Frame Number N
DS3 Frame Number N + 1
Note: TxFrameRef is pulsed high to denote
first nibble within a new DS3 frame
Nibble [1]
Nibble [1]
Sampling edge of the XRT72L13
How to configure the XRT72L13 into Mode 5
1. Set the "NibIntf" input pin "high".
2. Set the TimRefSel[1:0] bit-fields (within the
"Framer Operating Mode" Register) to "01" as
illustrated below.
OPERATING MODE REGISTER (ADDRESS = 0X00)
BIT 7
BIT 6
BIT 5
BIT 4
Local Loop-
back
Mode
Line Loop-
back
Mode
Internal LOS
Enable
RESET
R/W
R/W
R/W
R/W
0
0
1
0
3. Interface the XRT72L13, to the Terminal Equip-
ment, as illustrated in Figure 71 .
4.2.1.6 Mode 6 - The "Nibble-Parallel/TxInClk/
Frame-Master" Interface" Mode
Behavior of the XRT72L13
BIT 3
BIT2
BIT 1
BIT 0
Interrupt
Enable
Reset
Frame Format
TimRefSel[1:0]
R/W
R/W
R/W
R/W
1
0
0
1
If the XRT72L13 has been configured to operate in
this mode, then the XRT72L13 will function as fol-
lows:
A. Local-Timed (Uses the "TxInClk" signal as the
Timing Reference)
In this mode, the Transmit Section of the XRT72L13
will use the TxInClk signal at its timing reference.
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