XRT73LC00A_08 Datasheet, PDF (29/63 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT

XRT73LC00A
E3/DS3/STS-1 LINE INTERFACE UNIT
REV. 1.0.1
Figure 9 illustrates the typical interface for the transmission of data in a Dual-Rail Format between the Terminal
Equipment and the Transmit Section of the XRT73LC00A.
FIGURE 9. 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 XRT73LC00A
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 10. HOW THE XRT73LC00A SAMPLES THE DATA ON THE TPDATA AND TNDATA INPUT PINS
Data
TPDATA
TNDATA
TCLK
1
1
0
0
The manner that the LIU handles Dual-Rail data is described below and illustrated in Figure 10. The
XRT73LC00A typically samples the data on the TPDATA and TNDATA input pins on the falling edge of TCLK.
TCLK is typically a clock signal that is of the selected data rate frequency. For the E3 data rate, TCLK is
34.368 MHz. For the DS3 data rate, TCLK is 44.736 MHz and for the SONET STS-1 rate, TCLK is 51.84 MHz.
In general, if the XRT73LC00A samples a “1” on the TPDATA input pin, the Transmit Section of the device
ultimately generates a positive polarity pulse via the TTIP and TRING output pins across a 1:1 transformer. If
the XRT73LC00A samples a “1” on the TNDATA input pin, the Transmit Section of the device ultimately
generates a negative polarity pulse via the TTIP and TRING output pins across a 1:1 transformer.
2.1.1 Accepting Single-Rail Data from the Terminal Equipment
Do the following if data is to be transmited from the Terminal Equipment to the XRT73LC00A in Single-Rail
format (a binary data stream) without having to convert it into a Dual-Rail format.
A. Configure the XRT73LC00A to operate in the HOST Mode or,
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