XRT73L02M Datasheet, PDF (25/46 Pages) Exar Corporation – TWO CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT

xr
XRT73L02M
TWO CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT
REV. 1.0.0
FUNCTIONAL DESCRIPTION:
Figure 1 shows the functional block diagram of the device. Each channel can be independently configured ei-
ther by Hardware Mode or by Host Mode to support E3, DS3 or STS-1 modes. A detailed operation of each
section is described below.
Each channel consists of the following functional blocks:
4.0 THE TRANSMITTER SECTION:
The Transmitter Section, within each Channel, accepts TTL/CMOS level signals from the Terminal Equipment
in selectable data formats.
• Convert the CMOS level B3ZS or HDB3 encoded data into pulses with shapes that are compliant with the
various industry standard pulse template requirements. Figures 7, 8 and 9 illustrate the pulse template
requirements.
• Encode the un-encoded NRZ data into either B3ZS format (for DS3 or STS-1) or HDB3 format (for E3) and
convert to pulses with shapes and width that are compliant with industry standard pulse template require-
ments. Figures 7, 8 and 9 illustrate the pulse template requirements.
• In Single-Rail or un-encoded Non-Return-to-Zero (NRZ) mode, data is input via TPOS_n pins while TNEG_n
pins must be grounded. The NRZ or Single-Rail mode is selected when the SR/DR input pin is “High” (in
Hardware Mode) or bit 0 of channel control register is “1” (in Host Mode). Figure 12 illustrates the Single-Rail
or NRZ format.
FIGURE 12. SINGLE-RAIL OR NRZ DATA FORMAT (ENCODER AND DECODER ARE ENABLED)
Data
TPData
TxClk
1
1
0
• In Dual-Rail mode, data is input via TPOS_n and TNEG_n pins. TPOS_n contains positive data and
TNEG_n contains negative data. The SR/DR input pin = “Low” (in Hardware Mode) or bit 0 of channel regis-
ter = “0” (in Host Mode) enables the Dual-Rail mode. Figure 13 illustrates the Dual-Rail data format.
FIGURE 13. DUAL-RAIL DATA FORMAT (ENCODER AND DECODER ARE DISABLED)
Data
TPData
TNData
TxClk
1
1
0
23