Datasheet
____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
134 of 366
10.13
Line Interface Units (LIU)
Each TDM port of the device has an on-chip line interface unit (LIU). The LIU contains three sections: the
transmitter, which drives pulses with standards-compliant waveshapes onto the outbound cable; the receiver,
which recovers clock and data from the inbound cable; and the jitter attenuator. The LIU can switch between T1
and E1 operation without changing any external components on either the transmit or Rx side. Figure 10-68 sho
ws
a recommended circuitry for software-selectable termination with protection. In this configuration the device can
connect to 100 T1 twisted pair, 110 J1 twisted pair, 120 E1 twisted pair or 75 E1 coax without component
changes. Table 10-59 li
sts recommended values and part numbers for the components in Figure 10-68. Table
10-60 lists the performance requirements for the transmit and Rx transformers.
Figure 10-68. LIU External Components, Longitudinal Protection
Table 10-59. LIU External Components
NAME DESCRIPTION PART MANUFACTURER NOTES
1.25A Slow Blow Fuse SMP 1.25 Bel Fuse 5
F1 to F4
1.25A Slow Blow Fuse F1250T Teccor Electronics 5
S1, S2 25V (max) Transient Suppressor P0080SA MC Teccor Electronics 1, 5
S3, S4,
S5, S6
180V (max) Transient Suppressor P1800SC MC Teccor Electronics 1, 4, 5
S7, S8 40V (max) Transient Suppressor P0300SC MC Teccor Electronics 1, 5
T1 and T2 Transformer 1:1CT and 1:2CT (3.3V, SMT) PE-68678 Pulse Engineering 2, 3, 5
T3 and T4 Dual Common-Mode Choke (SMT) PE-65857 Pulse Engineering 5
R
T
Termination Resistor (120, 110, 100, or 75)
— — 8
Note 1: Changing S7 and S8 to P1800SC devices provides symmetrical voltage suppression between tip, ring, and ground.
Note 2: The layout from the transformers to the network interface is critical. Traces should be at least 25 mils wide and separated from
other circuit lines by at least 150 mils. The area under this portion of the circuit should not contain power planes.
Note 3: Some T1 (never in E1) applications source or sink power from the network-side center taps of the Rx/Tx transformers.
Note 4: The ground trace connected to the S3/S4 pair and the S5/S6 pair should be at least 50 mils wide to conduct the extra current
from a longitudinal power-cross event.
Note 5: Alternative component recommendations and line interface circuits can be found in Application Note 324, which is available at
www.maxim-ic.com/AN324 o
r by contacting tech support at www.maxim-ic.com/support.
DS34T10x
TTIPn
TRINGn
RTIPn
RRINGn
S1
S2
S3
S4
S5
S6
S7
S8
T1
T2
T3
T4
2:1
1:1
F1
F2
F3
F4
TX
TIP
TX
RING
RX
TIP
RX
RING
560 pF
R
T
1 uF