XRT83L314IB View Datasheet(PDF) - Exar Corporation
Part Name
Description
MFG CO.
'XRT83L314IB' PDF : 84 Pages View PDF
XRT83L314
14-CHANNEL T1/E1/J1 LONG-HAUL/SHORT-HAUL LINE INTERFACE UNIT
REV. 1.0.0
4.1.3 Digital Loopback
With digital loopback activated, the transmit input data at TCLK/TPOS/TNEG is looped back to the receive
output data at RCLK/RPOS/RNEG. The digital loopback mode includes the Transmit JA (if enabled). The
receive input data at RTIP/RRING is ignored while valid transmit output data continues to be sent to the line. A
simplified block diagram of digital loopback is shown in Figure 33.
FIGURE 33. SIMPLIFIED BLOCK DIAGRAM OF DIGITAL LOOPBACK
TCLK
TPOS
TNEG
NLC/PRBS/QRSS
Encoder
JA
RCLK
RPOS
RNEG
Decoder
JA
TAOS
Timing
Control
Tx
Data and
Clock
Rx
Recovery
TTIP
TRING
RTIP
RRING
4.1.4 Dual Loopback
With dual loopback activated, the remote loopback is combined with the digital loopback. A simplified block
diagram of dual loopback is shown in Figure 34.
FIGURE 34. SIMPLIFIED BLOCK DIAGRAM OF DUAL LOOPBACK
TCLK
TPOS
TNEG
NLC/PRBS/QRSS
Encoder
JA
RCLK
RPOS
RNEG
Decoder
JA
TAOS
Timing
Control
Tx
Data and
Clock
Rx
Recovery
TTIP
TRING
RTIP
RRING
35
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