XRT73LC04A
4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
REV. 1.0.1
2.0 THE TRANSMIT SECTION
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 T
HE
T
RANSMIT
L
OGIC
B
LOCK
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)
mission of data in a Dual-Rail Format between the
Terminal Equipment and the Transmit Section of the
XRT73LC04A.
F
IGURE
14. T
HE TYPICAL INTERFACE FOR THE
T
RANSMISSION OF
D
ATA IN A
D
UAL
-R
AIL
F
OR
-
MAT FROM THE
T
RANSMITTING
T
ERMINAL
E
QUIPMENT TO THE
T
RANSMIT
S
ECTION OF A CHANNEL
TxPOS
Terminal
Equipment
(E3/DS3 or STS-1
Framer)
TxNEG
TPData
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).
F
IGURE
15. T
HE
XRT73LC04A S
AMPLES THE DATA ON THE
TPD
ATA AND
TND
ATA INPUT PINS
Data
1
1
0
TPData
TNData
TxClk
28
EXAR [ EXAR CORPORATION ]
