Figure 13. Point-to-Point Broadcast Using MAX9150 Repeater
A point-to-point version of the multidrop bus is shown in
Figure 13. The low-jitter MAX9150 10-port repeater is
used to reproduce and transmit the serializer output
over 10 double-terminated point-to-point links.
Compared to the multidrop bus, more interconnect is
traded for more robust hot-plug capability.
The repeater eliminates nine serializers compared to 10
individual point-to-point serializer-to-deserializer con-
nections. Since repeater jitter subtracts from the serial-
izer-deserializer timing margin, a low-jitter repeater is
essential in most high data rate applications.
Multiple serializers and deserializers bused over a dif-
ferential serial connection on a backplane are shown in
Figure 14. The second serializer can be a backup to
the primary serializer. The typical close spacing (1in or
less) of cards on a backplane reduces the characteris-
tic impedance by as much as half the initial, unloaded
value. Termination resistors that match the loaded char-
acteristic impedance are required at each end of the
bus. The total loaded seen by the serializer is 27Ω in
this case.
Board Layout
For bus LVDS applications, a four-layer PCB that pro-
vides separate power, ground, and input/output signals
is recommended. Separate LVTTL/LVCMOS and bus
LVDS signals from each other to prevent coupling into
the bus LVDS lines.
