XRT73LC00 Datasheet, PDF (25/53 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT

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PRELIMINARY
XRT73LC00
E3/DS3/STS-1 LINE INTERFACE UNIT
REV. P1.0.1
4. The on-chip Pulse-Shaping circuitry is configured
to generate Transmit Output pulses of the correct
shape and width to meet the applicable pulse
template requirement.
5. The LOS Declaration/Clearance Criteria is estab-
lished.
2.0 THE TRANSMIT SECTION
Figure 1 indicates that the Transmit Section of the
XRT73LC00 consists of the following blocks:
• Transmit Logic Block
• Duty Cycle Adjust Block
• HDB3/B3ZS Encoder
• Pulse Shaping Block
The purpose of the Transmit Section in the
XRT73LC00 is to take TTL/CMOS level data from the
terminal equipment and encode it into a format that
can:
1. be efficiently transmitted over coaxial cable at E3,
DS3 or STS-1 data rates.
2. be reliably received by the Remote Terminal 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 (a binary data stream)
TTL/CMOS level data and timing information from the
Terminal Equipment.
Accepting Dual-Rail Data from the Terminal
Equipment
The XRT73LC00 accepts Dual-Rail data from the Ter-
minal Equipment via the following input signals:
• TPDATA
• TNDATA
• TCLK
Figure 11 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
XRT73LC00.
FIGURE 11. THE TYPICAL INTERFACE FOR THE TRANSMISSION OF DATA IN A DUAL-RAIL FORMAT FROM THE TRANS-
MITTING TERMINAL EQUIPMENT TO THE TRANSMIT SECTION OF THE XRT73LC00
TxPOS
TPDATA
Terminal
EquTipemrmeinntal
(E3/DSE3quoipr ^mSTeSnt-1
(E3F/DraSm3eor)r STS-1
Framer)
TxNEG
TxLineClk
TNDATA
TCLK
Transmit
LToragnicsmit
BloLcokgic
Block
Exar E3/DS3/STS-1 LIU
FIGURE 12. HOW THE XRT73LC00 SAMPLES THE DATA ON THE TPDATA AND TNDATA INPUT PINS
Data
TPDATA
TNDATA
TCLK
1
1
0
0
22