XRT75R12D_06 Datasheet, PDF (32/134 Pages) Exar Corporation – TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET

XRT75R12D
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER REV. 1.0.1
4.0 THE TRANSMITTER SECTION
The transmitter is designed so that the LIU can accept serial data from a local device, encode the data
properly, and then output an analog pulse according to the pulse shape chosen in the appropriate registers.
This section describes the detailed operation of various blocks within the transmit path. A simplified block
diagram of the transmit path is shown in Figure 13.
FIGURE 13. TRANSMIT PATH BLOCK DIAGRAM
TTIP_n
TRing_n
MTIP_n
MRing_n
DMO_n
Line
Driver
Device
Monitor
Tx
Pulse
Shaping
Tx
Control
Timing
Control
Jitter
Attenuator
MUX
HDB3/
B3ZS
Encoder
Channel n
TxClk_n
TxPOS_n
TxNEG_n
TxON
Transmit Digital Input Interface
The method for applying data to the transmit inputs of the LIU is a serial interface consisting of TxClk, TxPOS,
and TxNEG. For single rail mode, only TxClk and TxPOS are necessary for providing the local data from a
Framer device or ASIC. Data can be sampled on either edge of the input clock signal by programming the
appropriate register. A typical interface is shown in Figure 14.
FIGURE 14. TYPICAL INTERFACE BETWEEN TERMINAL EQUIPMENT AND THE XRT75R12D (DUAL-RAIL DATA)
TxPOS
TPData
Terminal
Equipment
(E3/DS3 or STS-1
Framer)
TxNEG
TxLineClk
TNData
TxClk
Transmit
Logic
Block
Exar E3/DS3/STS-1 LIU
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