XRT75L04 Datasheet, PDF (53/57 Pages) Exar Corporation – FOUR CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER

XRT75L04
REV. 1.0.4
FOUR CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER ATTENUATOR
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 passed through the jitter attenuator
using RxClk as the transmit timing.
NOTE: Input signals on TxClk, TPOS and TNEG are ignored during Remote loopback.
FIGURE 28. REMOTE LOOPBACK
TCLK
TPDATA
TNDATA
1
HDB3/B3ZS
ENCODER
TIMING
Tx
CONTROL
TTIP
TRING
RCLK
RPOS
RNEG
1
HDB3/B3ZS
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_n pins “High” or in Host
mode by setting the TAOS_n 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_n and TRING_n pins.
The frequency of this “1’s” pattern is determined by TClk_n.TAOS data path is shown in Figure 29.
FIGURE 29. TRANSMIT ALL ONES (TAOS)
TCLK
TPDATA
TNDATA
1
HDB3/B3ZS
ENCODER
TIMING
CONTROL
TAOS
TTIP
Tx
Transmit All 1
TRING
RCLK
RPOS
RNEG
1
HDB3/B3ZS
DECODER
DATA &
CLOCK
Rx
RECOVERY
1 _{if enabled}
2 _{if enabled and selected in either Receive or}
Transmit path
RTIP
RRING
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