Datasheet

____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
141 of 366
It is acceptable to provide a gapped/bursty clock at the TCLKFn p
in if the jitter attenuator is placed in the transmit
side. If the incoming jitter exceeds 120UI
P-P
(when buffer depth is 128 bits) or 28UI
P-P
(when buffer depth is 32 bits),
then the device sets the jitter attenuator limit trip (LLSR.JALTS
).
Figure 10-74. Jitter Attenuation
FREQUENCY (Hz)
0dB
-20dB
-40dB
-60dB
1 10 100 1K 10K
JITTER ATTENUATION (dB)
100K
TR 62411 (Dec. 90)
Prohibited Area
C
u
rv
e
B
Cu
rv
e
A
ITU G.7XX
Prohibited Area
TBR12
Prohibited
Area
T1E1
Note: Curve B applies only in T1 mode.
10.13.5 LIU Loopbacks
The LIU block provides four loopback paths for diagnostic purposes: analog loopback, local loopback, remote
loopback and dual loopback. The loopbacks are enabled by setting LMCR.LB[2:0
] to a non-zero value.
10.13.5.1 Analog Loopback
In analog loopback, the transmitter’s analog output on TTIP/TRING is looped back to the receiver’s analog input.
The signal on RTIP/RRING is ignored du
ring analog loopback. This loopback is shown in Figure 10-75.
Figure 10-75. Analog Loopback
Transmit
Frame
r
Receive
Frame
r
Optional
Jitte
r
A
ttenuato
r
Optional
Jitte
r
A
ttenuato
r
Line
Drive
r
Transmit
Digital
Transmit
A
nalog
Receive
Digital
Receive
A
nalog
RTIP
RRING
RCLK
RSER
TCL
K
TSER