XRT75VL00_08 Datasheet, PDF (34/50 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR

XRT75VL00
E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR
REV. 1.0.6
As defined in ITU-T G.775, an LOS condition is also declared between 10 and 255 UI (or E3 bit periods) after
the actual time the LOS condition has occurred. The LOS condition is cleared within 10 to 255 UI after
restoration of the incoming line signal. Figure 20 shows the LOS declaration and clearance conditions.
FIGURE 20. LOSS OF SIGNAL DEFINITION FOR E3 AS PER ITU-T G.775.
RTIP/
RRing
Actual Occurrence
of LOS Condition
Line Signal
is Restored
10 UI
255 UI
Time Range for
LOS Declaration
10 UI
255 UI
RLOS Output Pin
0 UI
G.775
Compliance
0 UI
Time Range for
LOS Clearance
G.775
Compliance
5.4.3 Muting the Recovered Data with LOS condition:
When the LOS condition is declared, the clock recovery circuit locks into the reference clock applied to the
ExClk pin and output this clock on the RxClk output. The data on the RPOS and RNEG pins can be forced to
zero by pulling the LOSMUT pin “High” (in Hardware Mode) or by setting the LOSMUT bits in the individual
channel control register to “1” (in Host Mode).
NOTE: When the LOS condition is cleared, the recovered data is output on RPOS and RNEG pins.
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