XRT81L27 Datasheet, PDF (24/30 Pages) Exar Corporation – SEVEN CHANNEL E1 LINE INTERFACE UNIT WITH CLOCK RECOVERY

XRT81L27
SEVEN CHANNEL E1 LINE INTERFACE UNIT WITH CLOCK RECOVERY
REV. 1.1.0
FIGURE 11. ITU-T G.703 PULSE TEMPLATE
269 ns
(244 + 25)
áç
V = 100%
194 ns
(244 – 50)
Nominal pulse
50%
0%
244 ns
219 ns
(244 – 25)
488 ns
(244 + 244)
Note – V corresponds to the nominal peak value.
2.5 THE LINE DRIVER BLOCK
The driver block will take the TP and TN pulses out of
the Pulse Shaping circuit and apply these to the TTIP
and TRING pins. Output drive control is available
from either a dedicated signal or (in Host mode) from
one of register control bits to turn the channel “off” by
placing the drivers in a high impedance state.
2.6 INTERFACING THE TRANSMIT SECTIONS OF THE
XRT81L27 TO THE LINE
In both (75Ω or 120Ω) applications, the user is ad-
vised to interface the Transmitter to the Line, using
the termination as shown in Figure 12. This includes
1:2 transformer with the intrinsic impedance of the
line used as a termination resistance.
The configuration differs only in the type of line con-
nects, The internal circuit adjusts to the load imped-
ance
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