LXT384
—
Octal T1/E1/J1 Transceiver
34
Datasheet
The monitored line signal (input or output) goes through channel 0 clock and data recovery. The
signal can be observed digitally at the RCLK/RPOS/RNEG outputs. This feature can also be used
to create timing interfaces derived from a E1 signal. Channel 0 also displays the appropriate LOS
state for the monitored channel, both in transmit and receive directions.
In addition, channel 0 can be configured to a Remote Loopback while in monitoring mode (TCLK0
must be active in order for this operation to take place). This will output the same data as in the
signal being monitored at the channel 0 output (TTIP/TRING). The output signal can then be
connected to a standard test equipment with an E1 electrical interface for monitoring purposes (non
-intrusive monitoring).
2.9
Hitless Protection Switching (HPS)
The LXT384 transceivers include an output driver tristatability feature for T1/E1 redundancy
applications. This feature greatly reduces the cost of implementing redundancy protection by
eliminating external relays. Please refer to Application Note 119 for guidelines for implementing
redundancy systems for both T1 and E1 operation using the LXT380/1/4/6/8.
2.10
Operation Mode Summary
Table 4
lists summarizes all the LXT384 hardware settings and corresponding operating modes.
Table 4. Operation Mode Summary
MCLK
TCLK
LOOP
1
Receive Mode
Transmit Mode
Loopback
Clocked
Clocked
Open
Data/Clock recovery
Pulse Shaping ON
No Loopback
Clocked
Clocked
L
Data/Clock recovery
Pulse Shaping ON
Remote Loopback
Clocked
Clocked
H
Data/Clock recovery
Pulse Shaping ON
Analog Loopback
Clocked
L
Open
Data/Clock recovery
Power down
No Loopback
Clocked
L
L
Data/Clock Recovery
Power down
No effect on op.
Clocked
L
H
Data/Clock Recovery
Power down
No Analog Loopback
Clocked
H
Open
Data/Clock Recovery
Transmit All Ones
No Loopback
Clocked
H
L
Data/Clock Recovery
Pulse Shaping ON
Remote Loopback
Clocked
H
H
Data/Clock Recovery
Transmit All Ones
No effect on op.
L
Clocked
Open
Power Down
Pulse Shaping ON
No Loopback
L
Clocked
L
Power Down
Pulse Shaping ON
No Remote Loopback
L
Clocked
H
Power Down
Pulse Shaping ON
No effect on op.
L
H
Open
Power Down
Pulse Shaping OFF
No Loopback
L
H
L
Power Down
Pulse Shaping OFF
No Remote Loop
L
H
H
Power Down
Pulse Shaping OFF
No effect on op.
L
L
X
Power Down
Power down
No Loopback
H
Clocked
Open
Data Recovery
Pulse Shaping ON
No Loopback
H
Clocked
L
Data Recovery
Pulse Shaping OFF
Remote Loopback
1. Hardware mode only.