XRT83SL28
xr
8-CHANNEL E1 SHORT-HAUL LINE INTERFACE UNIT
REV.1.0.0
3.2.5
Transmit Interface with N+1 Redundancy
For N+1 redundancy, the transmitters on all cards can be programmed for internal impedance. The
transmitters on the backup card do not have to be tri-stated. To swap the primary card, close the desired
relays. A 0.68uF capacitor is used in series with TTIP for blocking DC bias. See Figure 23 for a simplified
block diagram of the transmit section for an N+1 redundancy scheme.
FIGURE 23. SIMPLIFIED BLOCK DIAGRAM OF THE TRANSMIT INTERFACE FOR N+1 REDUNDANCY
Backplane Interface
Line Interface Card
Primary Card
XRT83SL28
0.68uF
1:2
1:2
1:2
Tx
E1 Line
E1 Line
E1 Line
Internal Impedance
Primary Card
XRT83SL28
0.68uF
Tx
Tx
Tx
Internal Impedance
Primary Card
XRT83SL28
0.68uF
Internal Impedance
Backup Card
XRT83SL28
0.68uF
Internal Impedance
28
EXAR [ EXAR CORPORATION ]
