Texas Instruments MuxIt-EVM Evaluation Module MUXIT-EVM MUXIT-EVM Datenbogen
Produktcode
MUXIT-EVM
Terminations and Multidrop Configurations
5-6
Figure 5–4. Deserializer LCI Trace Routing
SN65LVDS150 (U1)
Layer1
Stub
TP2
LCI
Fly-by Routing
SN65LVDS151 (U2)
Layer6
Deserializer Board
SN65LVDS151 (U3)
LCI Termination
Resistor
SN65LVDS151 (U4)
R4
Stub
5.2
Terminations and Multidrop Configurations
Designers should notice that an internal termination resistor is provided on the
CI input of the SN65LVDS151 serializer-transmitter. All other LVDS inputs are
not internally terminated. The reason for this is to allow multiple receivers to
be connected in a multidrop configuration. This is illustrated in Figure 5–5.
CI input of the SN65LVDS151 serializer-transmitter. All other LVDS inputs are
not internally terminated. The reason for this is to allow multiple receivers to
be connected in a multidrop configuration. This is illustrated in Figure 5–5.
If a user has more than one MuxIt EVM, then multidrop operation can be
evaluated. System designers can use multiple drops of an LVDS link as long
as there is only one termination, located at the end of the transmission line. As
described earlier, the multiple drops from the LVDS signals are stubs, and
these stub lengths need to be kept as short as possible to minimize reflections
on the LVDS lines. Using the multiple EVMs in multidrop operation would
create stubs that are equivalent to the trace length from the input connector
(A2:J2) to the device input. Such stub lengths may impact the evaluation of
MuxIt in a multidrop configuration. Also note that one or more of the
terminations on the EVMs must be removed so that only one termination exists
at the end of each transmission line. In the example depicted in Figure 5–5,
the removal of terminations for LCI/CRI and CASCADE_DI (resistors R5 and
R1) on A2–2 is recommended.
evaluated. System designers can use multiple drops of an LVDS link as long
as there is only one termination, located at the end of the transmission line. As
described earlier, the multiple drops from the LVDS signals are stubs, and
these stub lengths need to be kept as short as possible to minimize reflections
on the LVDS lines. Using the multiple EVMs in multidrop operation would
create stubs that are equivalent to the trace length from the input connector
(A2:J2) to the device input. Such stub lengths may impact the evaluation of
MuxIt in a multidrop configuration. Also note that one or more of the
terminations on the EVMs must be removed so that only one termination exists
at the end of each transmission line. In the example depicted in Figure 5–5,
the removal of terminations for LCI/CRI and CASCADE_DI (resistors R5 and
R1) on A2–2 is recommended.