Altera Arria II GX FPGA Development Board - Manual (Page 37)

Chapter 2: Board Components 2–29
Components and Interfaces
February 2011 Altera Corporation Arria II GX FPGA Development Board Reference Manual
The power for the board can be sourced entirely from the PCI Express edge connector
when installed into a PC motherboard. Although the board can also be powered by a
laptop power supply for use on a lab bench, it is not recommended to power from
both supplies at the same time. This board includes ideal diode power sharing devices
to prevent damages or back-current from one supply to the other.
The PCIE_REFCLK_P signal is a 100 MHz differential input that is driven from the PC
motherboard on to this board through the edge connector. This signal connects
directly to a Arria II GX REFCLK input pin pair using DC coupling. This clock is
terminated on the motherboard and therefore, no on-board termination is required.
This clock can have spread-spectrum properties that change its period between
9.847 ps to 10.203 ps. The I/O standard is HCSL.
Figure 2–8 shows the PCI Express reference clock levels.
The JTAG and SMB are optional signals in the PCI Express specification. Both types of
signals are wired to the Arria II GX device but are not required for normal operation.
The PCI Express control DIP switch allows the presence detect grounding to be
altered to enable a ×1, ×4, or ×8 width edge connector. The PCI Express control DIP
switch does not support auto-negotiation.
Table 2–34 summarizes the PCI Express pin assignments. The signal names and
directions are relative to the Arria II GX FPGA.
Figure 2–8. PCI Express Reference Clock Levels
V MAX = 1.15 V
V CROSS MAX = 550 mV
V CROSS MIN = 250 mV
V MIN = –0.30 V
REFCLK –
REFCLK +
Table 2–34. PCI Express Pin Assignments, Schematic Signal Names, and Functions (Part 1 of 2)
Board Reference Description Schematic Signal
Name
I/O Standard
Arria II GX Device
Pin Number
J14.B14 Add-in card receive bus PCIE_RX_P0
1.5-V PCML
AN33
J14.B15 Add-in card receive bus PCIE_RX_N0 AN34
J14.B19 Add-in card receive bus PCIE_RX_P1 AL33
J14.B20 Add-in card receive bus PCIE_RX_N1 AL34
J14.B23 Add-in card receive bus PCIE_RX_P2 AJ33
J14.B24 Add-in card receive bus PCIE_RX_N2 AJ34
J14.B27 Add-in card receive bus PCIE_RX_P3 AG33
J14.B28 Add-in card receive bus PCIE_RX_N3 AG34
J14.B33 Add-in card receive bus PCIE_RX_P4 AE33
J14.B34 Add-in card receive bus PCIE_RX_N4 AE34