25
Chapter 2 Installation Instructions
NF4K8AB Series User Manual
PEX PLL REFCLK Select Jumper: J3A1
This jumper is used to select the resource for PCI
Express PLL reference clock.
PEX REFCLK Jumper: J1G1
This jumper is used to select common-mode level
range for PCI Express external reference clock input
pins.
Internal clock
reference
(Default)
External
clock
reference
PE_REFCLK Select Jumper
below VDD/2
(Default)
above VDD/2
PEX REFCLK Jumper
Recovery Jumper: J1E1
This jumper is reserved for technology support,
please do not change the jumper.
1
2
Open
Closed
(Default)
1
2
Recovery Jumper