Texas Instruments SN65LVDS386EVM, Руководство пользователя

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SN65LVDS387 16-Channel LVDS Line Driver
2-3
The Evaluation Boards
2.1 SN65LVDS387 16-Channel LVDS Line Driver
This 16-channel LVDS driver accepts 16 low-voltage TTL (LVTTL) inputs and
generates 16 LVDS differential outputs (please refer to the schematic in
Appendix I). Connectors P1/P2 are the LVTTL I/O connectors. Connectors P3
through P7 are the LVDS I/O connectors. The LVTTL inputs can be provided
by any suitable source. As shipped, the SN65LVDS387EVM has 50-
Ω
termination resistors (R33 through R48) installed on each LVTTL input line to
accommodate inputs from a pattern generator or other instrumentation that
has a 50-
Ω
source impedance. If the LVTTL source and cable being used is
not a 50-
Ω
source, then these resistors (resistors R33 through R48) need to
be removed. They are required to match the characteristic impedance of the
cable (and the source impedance of most pattern generators). These resistors
are located on the back (under) side of the SN65LVDS386EVM, next to the
P1/P2 connector row.
The other optional components are resistors R1 through R32. Resistors R1
through R16 are left open on the SN65LVDS387EVM. These are used in the
LVDS output circuit and, since LVDS lines are normally terminated at the input
to the receiver, these 100-
Ω
resistors are not installed on the EVM. If users
want to measure specific performance parameters on the ’387, then they are
responsible for installing 100-ohm resistors in R1 through R16. Zero-ohm
resistors are installed in R17 through R32, which are in series with the LVTTL
inputs to the SN65LVDS387. The remaining components are connectors for
Vcc and Gnd connections, and decoupling capacitors for the LVDS device.
These components are the same for both configurations of the EVM.
There are also four jumpers (JMP1 through JMP4 ) located next to the P1/P2
connector row. These jumpers control the enable and disable for each four-
channel (quad) section of the device. Each of these jumpers consist of three
pins and a jumper short. The center pin is connected to the device and the out-
er pins (top and bottom) are V
CC
and GND. The jumper short can be moved
so contact is made between V
CC
and the enable/disable pin, or between GND
and the enable/disable pin. As shipped, the four jumper shorts are installed to
V
CC
so that all four sections of the device are enabled. A photograph of the
SN65LVDS387EVM is shown is Figure 2–2.