XRT73L03 View Datasheet(PDF) - Exar Corporation
Part Name
Description
MFG CO.
'XRT73L03' PDF : 62 Pages View PDF
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PRELIMINARY
3 CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT XRT73L03
REV. P1.0.13
TABLE 3: SELECTING THE DATA RATE FOR CHANNEL(N) OF THE XRT73L03, VIA THE E3_CH(N) AND STS-1/
DS3_CH(N) INPUT PINS (HARDWARE MODE)
DATA RATE
STATE OF E3_CH(N) PIN
(PIN 64, 92, 102)
STATE OF STS-1/DS3_CH(N)
PIN
(PIN 65, 95, 101)
MODE OF B3ZS/HDB3 ENCODER/
DECODER BLOCKS
E3 (34.368 Mbps)
1
X (Don't Care)
HDB3
DS3 (44.736 Mbps)
0
0
B3ZS
STS-1 (51.84 Mbps)
0
1
B3ZS
b. Operating in the HOST Mode.
To configure the Data Rate of a Channel, write the
appropriate values into the STS-1/DS3_Ch(n) and
E3_Ch(n) bit-fields in Command Register CR4-(n).
NOTE: Reference Table 2 for the correct address of each
channel.
COMMAND REGISTER CR4-(N)
D4
D3
D2
D1
D0
X STS-1/(DS3)_(n)) E3_Ch(n) LLB(n) RLB(n)
x
x
x
x
x
Table 4 relates the values of these two bit-fields to the
selected data rates.
TABLE 4: SELECTING THE DATA RATE FOR CHANNEL(N)
OF THE XRT73L03 VIA THE STS-1/DS3_CH(N) AND
THE E3_CH(N) BIT-FIELDS IN THE APPROPRIATE
COMMAND REGISTER (HOST MODE)
SELECTED DATA
RATE
E3
DS3
STS-1
STS-1/DS3_(N)
(D3)
X (Don't Care)
0
1
E3_CH(N)
(D2)
1
0
0
2.0 THE TRANSMIT SECTION
Figure 8 shows the Transmit Section in each Channel
of the XRT73L03 consists of the following blocks:
• Transmit Logic Block
• TxClk(n) Duty Cycle Adjust Block
• HDB3/(B3ZS) Encoder
• Pulse Shaping Block
The purpose of the Transmit Section in each Channel
of the XRT73L03 is to take TTL/CMOS level data
from the Terminal Equipment and encode it into a for-
mat 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
Equipment at the other end of the E3, DS3 or
STS-1 data link, and
3. comply with the applicable pulse template
requirements.
The circuitry that the Transmit Section in each Chan-
nel of the XRT73L03 takes to accomplish this goal is
discussed below.
2.1 THE TRANSMIT LOGIC BLOCK
The purpose of the Transmit Logic Block is to accept
either Dual-Rail or Single-Rail (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 XRT73L03 accepts Dual-Rail data
from the Terminal Equipment, it does so via the fol-
lowing input signals:
• TPData(n)
• TNData(n)
• TxClk(n)
Figure 9 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
XRT73L03.
26
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