Xilinx SelectIO 7 Series User Manual

7 Series FPGAs SelectIO Resources User Guide www.xilinx.com 91
UG471 (v1.10) May 8, 2018
Supported I/O Standards and Terminations
LVDS and LVDS_25 (Low Voltage Differential Signaling)
Low-voltage differential signaling (LVDS) is a powerful high-speed interface in many
system applications. 7 series FPGA I/Os are designed to comply with the EIA/TIA
electrical specifications for LVDS to make system and board design easier. With the use of
an LVDS current-mode driver in the IOBs and the optional internal differential termination
feature, the need for external source termination in point-to-point applications is
eliminated. 7 series devices provide the most flexible solution for doing an LVDS design in
an FPGA.
The LVDS I/O standard is only available in the HP I/O banks. It requires a V
CCO
to be
powered at 1.8V for outputs and for inputs when the optional internal differential
termination is implemented (DIFF_TERM = TRUE).
The LVDS_25 I/O standard is only available in the HR I/O banks. It requires a V
CCO
to be
powered at 2.5V for outputs and for inputs when the optional internal differential
termination is implemented (DIFF_TERM = TRUE).
Transmitter Termination
The 7 series FPGA LVDS transmitter does not require any external termination. Table 1-44
lists the allowed attributes corresponding to the 7 series FPGA LVDS current-mode
drivers. 7 series FPGA LVDS current-mode drivers are a true current source and produce
the proper (EIA/TIA compliant) LVDS signal.
Receiver Termination
Figure 1-70 is an example of differential termination for an LVDS or LVDS_25 receiver on a
board with 50Ω transmission lines.
Table 1-42: SLEW Attribute for All Single-Ended and Differential HSTL, SSTL, HSUL, and Mobile_DDR
IOSTANDARDs
Attribute
Primitives
IBUF, IBUFG, IBUFDS, IBUFGDS,
IBUFDS_DIFF_OUT, or IBUFGDS_DIFF_OUT
OBUF, OBUFT, OBUFDS, or OBUFTDS, IOBUF,
IOBUFDS or IOBUFDS_DIFF_OUT
HP I/O Banks HR I/O Banks HP I/O Banks HR I/O Banks
SLEW N/A N/A {FAST, SLOW} {FAST, SLOW}
Table 1-43: Available I/O Bank Type
HR HP
Available for LVDS_25 only Available for LVDS only
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Xilinx SelectIO 7 Series Specifications

General

Brand	Xilinx
Model	SelectIO 7 Series
Category	Computer Hardware
Language	English