XRT79L71 Datasheet, PDF (115/441 Pages) Exar Corporation – 1 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC

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PRELIMINARY
1 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
XRT79L71
REV. P1.0.3
BIT
NUMBER
NAME
3
FL Alarm Declared
2
Receive LOL
Condition Declared
TYPE
R/O
R/O
DEFAULT
VALUE
0
0
DESCRIPTION
FL (FIFO Limit) Alarm Declared:
This READ-ONLY bit-field indicates whether or not the Jitter
Attenuator block (within the XRT79L71 device) is currently
declaring the FIFO Limit Alarm.
The Jitter Attenuator block will declare the "FIFO Limit"
Alarm anytime the "Jitter Attenuator" FIFO comes within two
bit-periods of either overflowing or under-running.
Conversely, the Jitter Attenuator block will clear the "FIFO
Limit" Alarm anytime the "Jitter Attenuator" FIFO is NO
longer within two bit-periods of either overflowing or under-
running.
Typically, this Alarm will only be declared whenever there is
a very serious problem with timing or jitter in the system.
0 - Indicates that the Jitter Attenuator block (within the
XRT79L71 device) is NOT currently declaring the "FIFO
Limit" Alarm condition.
1 - Indicates that the Jitter Attenuator block (within the
XRT79L71 device) is currently declaring the "FIFO Limit"
Alarm condition.
NOTE: This bit-field is only active if the Jitter Attenuator
(within the XRT79L71 device) has been enabled.
Receive LOL (Loss of Lock) Condition Declared:
This READ-ONLY bit-field indicates whether or not the
Receive Section (within the XRT79L71 device) is currently
declaring the LOL (Loss of Lock) condition.
The Receive Section (of XRT79L71) will declare the LOL
Condition, if any one of the following conditions is met.
• If the frequency of the Recovered Clock signal differs
from that of the signal provided to the E3CLK input (for E3
applications) or the DS3CLK input (for DS3 applications)
by 0.5% (or 5000ppm) or more.
• If the frequency of the Recovered Clock signal differs
from the "line-rate" clock signal (for XRT79L71) that has
been generated by the "SFM Clock Synthesizer" PLL (for
SFM Mode Operation) by 0.5% (or 5000ppm) or more.
0 - Indicates that the Receive Section of XRT79L71 is NOT
currently declaring the LOL Condition.
1 - Indicates that the Receive Section of XRT79L71 is cur-
rently declaring the LOL Condition.
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