Clocking; Pcie Reference Clocks; Fabric Clock; Programming Clock (Emcclk) - Alpha Data ADM-PCIE-8V3 User Manual

3.2 Clocking

The ADM-PCIE-8V3 provides reference clocks for the DDR4 SDRAM banks and the I/O interfaces available to
the user. After a clock is programmed to a certain frequency, that frequency will become the default on power-up.
Any clock out of an Si5338 Clock Synthesizer is re-configurable over I2C. This allows the user to configure
almost any arbitrary clock frequencies during application run time. Please see the Alpha Data API functions for
examples of how this is done.
Note: use "set_property BITSTREAM.CONFIG.UNUSEDPIN {Pullnone} [current_design]" to ensure the user
design does not interfere with the I2C interface to the reprogramable clock generator.
Card Edge PCIe Ref Clock (100MHz)
25MHz
30ppm
Source

3.2.1 PCIe Reference Clocks

The 16 MGT lanes connected to the PCIe card edge use MGT tiles 224 through 227 and use the system 100
MHz clock (PCIE_REFCLK).
PCIE_REFCLK

3.2.2 Fabric Clock

The design offers a fabric clock called FABRIC_CLK which is permanently fixed at 300 MHz. This clock is
intended to be used for IDELAY elements in FPGA designs. The fabric clock is connected to a Global Clock (GC)
pin.
FABRIC_CLK

3.2.3 Programming Clock (EMCCLK)

An 100MHz clock is fed into the EMCCLK pin to drive the BPI flash device during configuration of the FPGA.
Page 8
NB6L11S
Fanout
NB6L11S
Fanout
Si5338
Clock
NB6L11S
Synth Fanout
Figure 7 : Clock Topology
Signal Target FPGA Input
MGTREFCLK0_226
Table 5 : PCIe Reference Clocks
Signal Target FPGA Input
IO_L12P_T1U_GC_94
PCIe Ref Clock (MGTREFCLK0_226)
QSFP28 161.1328125MHz Factory Default (MGTREFCLK0_128)
QSFP28 161.1328125MHz Factory Default (MGTREFCLK0_129)
FireFly 161.1328125MHz Factory Default (MGTREFCLK0_125)
FireFly 161.1328125MHz Factory Default (MGTREFCLK0_126)
Memory Interface Clock 300Mhz (IO Bank 44)
Memory Interface Clock 300Mhz (IO Bank 94)
FABRIC_CLK 300MHz (IO Bank 94)
I/O Standard
I/O Standard
DIFF_HSTL_I_18
Table 6 : Fabric Clock
ADM-PCIE-8V3 User Manual
"P" pin
HCSL AA7
"P" pin
AP26
Functional Description
"N" pin
AA6
"N" pin
AP27
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