A3PE1500-2FG676 Datasheet, PDF (62/164 Pages) Microsemi Corporation – ProASIC3E Flash Family FPGAs

ProASIC3E DC and Switching Characteristics
Differential I/O Characteristics
Physical Implementation
Configuration of the I/O modules as a differential pair is handled by the Designer software when the user
instantiates a differential I/O macro in the design.
Differential I/Os can also be used in conjunction with the embedded Input Register (InReg), Output
Register (OutReg), Enable Register (EnReg), and DDR. However, there is no support for bidirectional
I/Os or tristates with the LVPECL standards.
LVDS
Low-Voltage Differential Signaling (ANSI/TIA/EIA-644) is a high-speed, differential I/O standard. It
requires that one data bit be carried through two signal lines, so two pins are needed. It also requires
external resistor termination.
The full implementation of the LVDS transmitter and receiver is shown in an example in Figure 2-22. The
building blocks of the LVDS transmitter-receiver are one transmitter macro, one receiver macro, three
board resistors at the transmitter end, and one resistor at the receiver end. The values for the three driver
resistors are different from those used in the LVPECL implementation because the output standard
specifications are different.
Along with LVDS I/O, ProASIC3E also supports Bus LVDS structure and Multipoint LVDS (M-LVDS)
configuration (up to 40 nodes).
OUTBUF_LVDS ^FPGA
Bourns Part Number: CAT16-LV4F12
P
165 
P
Z₀ = 50 
140 
100 
N
165 
Z₀ = 50 
N
FPGA
+
INBUF_LVDS
–
Figure 2-22 • LVDS Circuit Diagram and Board-Level Implementation
2-48
Revision 12