lxt351 Intel Corporation, lxt351 Datasheet - Page 19

• Manufacturer Part Number: lxt351
• Description: T1/e1 Short Haul Transceiver With Crystal-less Jitter Attenuation
• Manufacturer: Intel Corporation

2.5.1.4
2.5.2
2.5.2.1
Datasheet
Figure 7. Remote Loopback
Figure 8. Dual Loopback
Dual Loopback
See
DLOOP mode, the transmit clock and data inputs (TCLK and TPOS/TNEG or TDATA) loop back
through the Jitter Attenuator (unless disabled) to RCLK and RPOS/RNEG or RDATA. The data
and clock recovered from the twisted-pair line loop back through the transmit circuits to TTIP and
TRING without jitter attenuation.
Internal Pattern Generation
Transmit All Ones
See
inputs and transmits a continuous stream of 1s at the TCLK frequency. (With no TCLK, the TAOS
output clock is MCLK.) This can be used as the Alarm Indication Signal (AIS–also called the Blue
Alarm). TAOS is commanded by writing a 1 to bit CR2.ETAOS. Both TAOS and Local loopback
can occur simultaneously as shown in
both TAOS and LLOOP are active, TCLK and TPOS/TNEG loop back to RCLK and RPOS/RNEG
through the jitter attenuator (if enabled), and an all ones pattern goes to TTIP/TRING.
Figure
Figure
T1/E1 Short Haul Transceiver with Crystal-less Jitter Attenuation — LXT351
8. To select Dual loopback (DLOOP) set bits CR2.ERLOOP and CR2.ELLOOP to 1. In
9. In Transmit All Ones (TAOS) mode, the transceiver ignores the TPOS and TNEG
Figure
4, however, Remote loopback inhibits TAOS. When
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