XRT83L30 Datasheet, PDF (35/78 Pages) Exar Corporation – SINGLE-CHANNEL T1/E1/J1 LH/SH TRANSCEIVER WITH CLOCK RECOVERY AND JITTER ATTENUATOR

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XRT83L30
ONE-CHANNEL T1/E1/J1 LH/SH TRANSCEIVER WITH CLOCK RECOVERY AND JITTER ATTENUATOR
PRELIMINARY
REV. P1.3.0
FIGURE 16. SIMPLIFIED BLOCK DIAGRAM OF THE TRANSMIT SECTION FOR 1:1 & 1+1 REDUNDANCY
Backplane Interface
Line Interface Card
Primary Card
XRT83L30
Tx
TxTSEL=1, Internal
0.68µF
1:2
T1/E1 Line
Backup Card
XRT83L30
Tx
TxTSEL=1, Internal
0.68µF
RECEIVE 1:1 & 1+1 REDUNDANCY
For 1:1 and 1+1 redundancy, the receivers on the primary card should be programmed for Internal Impedance
mode. The receivers on the backup card should be programmed for External Impedance mode. Since there is
no external resistor in the circuit, the receivers on the backup card will be high impedance. This key design
feature eliminates the need for relays and provides one bill of materials for all interface modes of operation.
Select the impedance for the desired mode of operation, T1/E1/J1. To swap the primary card, set the backup
card to Internal Impedance mode, then the primary card to External Impedance mode. See Figure 17 for a
simplified block diagram of the receive section for a 1:1 and 1+1 redundancy scheme.
NOTE: For simplification, the over voltage protection circuitry was omitted.
FIGURE 17. SIMPLIFIED BLOCK DIAGRAM - RECEIVE SECTION FOR 1:1 AND 1+1 REDUNDANCY
Backplane Interface
Line Interface Card
Primary Card
XRT83L30
Rx
RxTSEL=1, Internal
1:1
T1/E1 Line
Backup Card
XRT83L30
Rx
RxTSEL=0, External
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