XRT75L00D Datasheet, PDF (50/92 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER

XRT75L00D
E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER
FIGURE 27. DIGITAL LOOPBACK
TCLK
TPDATA
TNDATA
HDB3/B3ZS¹
ENCODER
TIMING
Tx
CONTROL
REV. 1.0.2
TTIP
TRING
RCLK
RPOS
RNEG
HDB3/B3ZS¹
DECODER
DATA &
CLOCK
Rx
RECOVERY
1 _{if enabled}
2 _{if enabled and selected in either Receive or Transmit path}
RTIP
RRING
8.2.3 REMOTE LOOPBACK:
With Remote loopback activated as shown in Figure 28,the receive data on RTIP and RRING is looped back
after the jitter attenuator (if selected in receive or transmit path) to the transmit path using RxClk as transmit
timing. The receive data is also output via the RPOS and RNEG pins.
During the remote loopback mode, if the jitter attenuator is selected in the transmit path, the receive data after
the Clock and Data Recovery Block is looped back to the transmit path and pass through the jitter attenuator
using RxClk as the transmit timing.
NOTE: Input signals on TxClk, TPDATA and TNDATA are ignored during Remote loopback.
FIGURE 28. REMOTE LOOPBACK
TCLK
TPDATA
TNDATA
HDB3/B3ZS ¹
ENCODER
TIMING
Tx
CONTROL
TTIP
TRING
RCLK
RPOS
RNEG
HDB3/B3ZS ¹
DECODER
1 _{if enabled}
2 _{if enabled and selected in either Receive or Transmit path}
DATA &
CLOCK
RECOVERY
RTIP
Rx
RRING
8.3 TRANSMIT ALL ONES (TAOS):
Transmit All Ones (TAOS) can be set either in Hardware mode by pulling the TAOS pins “High” or in Host mode
by setting the TAOS control bits to “1” in the Channel control registers. When the TAOS is set, the Transmit
Section generates and transmits a continuous AMI all “1’s” pattern on TTIP and TRING pins. The frequency of
this “1’s” pattern is determined by TClk.TAOS data path is shown in Figure 29.
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