XRT83L314 Datasheet, PDF (32/84 Pages) Exar Corporation – 14-CHANNEL T1/E1/J1 LONG-HAUL/SHORT-HAUL LINE INTERFACE UNIT

XRT83L314
14-CHANNEL T1/E1/J1 LONG-HAUL/SHORT-HAUL LINE INTERFACE UNIT
REV. 1.0.0
3.3 Transmit Jitter Attenuator
The XRT83L314 LIU is ideal for multiplexer or mapper applications where the network data crosses multiple
timing domains. As the higher data rates are de-multiplexed down to T1 or E1 data, stuffing bits are typically
removed which can leave gaps in the incoming data stream. The transmit path has a dedicated jitter
attenuator with a 32-Bit or 64-Bit FIFO that is used to smooth the gapped clock into a steady T1 or E1 output.
The maximum gap width of the 14-Channel LIU is shown in Table 10.
TABLE 10: MAXIMUM GAP WIDTH FOR MULTIPLEXER/MAPPER APPLICATIONS
FIFO DEPTH
MAXIMUM GAP WIDTH
32-Bit
20 UI
64-Bit
50 UI
NOTE: If the LIU is used in a loop timing system, the receive path has a dedicated jitter attenuator. See the Receive
Section of this datasheet.
3.4 TAOS (Transmit All Ones)
The XRT83L314 has the ability to transmit all ones on a per channel basis by programming the appropriate
channel register. This function takes priority over the digital data present on the TPOS/TNEG inputs. For
example: If a fixed "0011" pattern is present on TPOS in single rail mode and TAOS is enabled, the transmitter
will output all ones. In addition, if digital or dual loopback is selected, the data on the RPOS output will be
equal to the data on the TPOS input. Figure 22 is a diagram showing the all ones signal at TTIP and TRING.
FIGURE 22. TAOS (TRANSMIT ALL ONES)
TAOS
1
1
1
3.5 Transmit Diagnostic Features
In addition to TAOS, the XRT83L314 offers multiple diagnostic features for analyzing network integrity such as
ATAOS, Network Loop Code generation, and QRSS on a per channel basis by programming the appropriate
registers. These diagnostic features take priority over the digital data present on TPOS/TNEG inputs. The
transmitters will send the diagnostic code to the line and will be maintained in the digital loopback if selected.
When the LIU is responsible for sending diagnostic patterns, the LIU is automatically placed in the single rail
mode.
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