XRT73LC04A_08 Datasheet, PDF (32/64 Pages) Exar Corporation – 4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT

XRT73LC04A
4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
REV. 1.0.2
2.0 THE TRANSMIT SECTION
Figure 13 indicates that the Transmit Section within
each Channel of the XRT73LC04A consists of the fol-
lowing blocks:
• Transmit Logic Block
• TxClk_(n) Duty Cycle Adjust Block
• HDB3/(B3ZS) Encoder
• Pulse Shaping Block
The purpose of the Transmit Section is to take TTL/
CMOS level data from the terminal equipment and
encode it into a format such that it can:
1. Be efficiently transmitted over coaxial cable at
E3, DS3, or STS-1 data rates.
2. Be reliably received by the Remote Terminal
Equipment at the other end of the E3, DS3, or
STS-1 data link.
3. Comply with the applicable pulse template
requirements.
2.1 THE TRANSMIT LOGIC BLOCK
The purpose of the Transmit Logic Block is to accept
either Dual-Rail or Single-Rail (e.g., a binary data
stream) TTL/CMOS level data and timing information
from the Terminal Equipment.
2.1.1 Accepting Dual-Rail Data from the Termi-
nal Equipment
Whenever the XRT73LC04A accepts Dual-Rail data
from the Terminal Equipment, it does so via the fol-
lowing input signals:
• TPData_(n)
• TNData_(n)
• TxClk_(n)
Figure 14 illustrates the typical interface for the trans-
mission of data in a Dual-Rail Format between the
Terminal Equipment and the Transmit Section of the
XRT73LC04A.
FIGURE 14. THE TYPICAL INTERFACE FOR THE TRANSMISSION OF DATA IN A DUAL-RAIL FOR-
MAT FROM THE TRANSMITTING TERMINAL EQUIPMENT TO THE TRANSMIT SECTION OF A CHANNEL
TxPOS TPData
Terminal
Equipment
(E3/DS3 or STS-1
Framer)
TxNEG TNData
TxLineClk TxClk
Transmit
Logic
Block
Exar E3/DS3/STS-1 LIU
The manner that the LIU handles Dual-Rail data is
described below and illustrated in Figure 15. The
Transmit Section (of a Channel) typically samples the
data on the TPData_(n) and TNData_(n) input pins
on the falling edge of TxClk_(n).
FIGURE 15. THE XRT73LC04A SAMPLES THE DATA ON THE TPDATA AND TNDATA INPUT PINS
Data
0
TPData
TNData
TxClk
1
1
0
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