XRT83SL314IB datasheet(40/83 Pages) EXAR

40 / 83 page

XRT83SL314

REV. 1.0.1

14-CHANNEL T1/E1/J1 SHORT-HAUL LINE INTERFACE UNIT

4.3

Transmit Jitter Attenuator

The XRT83SL314 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 11.

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.

4.4

TAOS (Transmit All Ones)

The XRT83SL314 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 32 is a diagram showing the all ones signal at TTIP and TRING.

FIGURE 32. TAOS (TRANSMIT ALL ONES)

4.5

Transmit Diagnostic Features

In addition to TAOS, the XRT83SL314 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.

TABLE 11: MAXIMUM GAP WIDTH FOR MULTIPLEXER/MAPPER APPLICATIONS

FIFO DEPTH

MAXIMUM GAP WIDTH

32-Bit

20 UI

64-Bit

50 UI

TAOS

XRT83SL314IB Datasheet(PDF) 40 Page - Exar Corporation