
2–26 Chapter 2: Board Components
Clock Circuitry
100G Development Kit, Stratix IV GT Edition Reference Manual September 2010 Altera Corporation
Two PLL/buffer devices (Si5338) drive the DDR3 and QDR II interfaces clocks
directly to the FPGA clock pins (as shown in the Figure 2–9).
Table 2–14 lists the clock signal names, board references, and functional descriptions.
Figure 2–9. Memory Clocks
PLL
25 MHz
Stratix IV GT
DDR3 Clocks
Si5338
PLL
25 MHz
QDR II Clocks
Si5338
Stratix IV GT
Table 2–14. Spread Spectrum Configuration DIP Switch Pin-Out (SW2) (Part 1 of 3)
Board
Reference Description
Schematic
Signal Name
I/O
Standard
Stratix IV
GT Device
Pin Name
Other
Connections
U21.9 XCVR PLL clock for differential clock
buffer A
BUFFA1_DIFF_CLK_P
LVDS
— U19.6
U21.10 XCVR PLL clock for differential clock
buffer A
BUFFA1_DIFF_CLK_N — U19.7
U21.13 XCVR PLL clock for reference clock
buffer A
BUFFA2_REF_CLK_P — U15.6
U21.14 XCVR PLL clock for reference clock
buffer A
BUFFA2_REF_CLK_N — U15.7
U21.17 XCVR PLL clock for differential clock
buffer B
BUFFB1_DIFF_CLK_P — U18.6
U21.18 XCVR PLL clock for differential clock
buffer B
BUFFB1_DIFF_CLK_N — U18.7
U21.21 XCVR PLL clock for reference clock
buffer B
BUFFB2_REF_CLK_P — U20.16
U21.22 XCVR PLL clock for reference clock
buffer B
BUFFB2_REF_CLK_N — U20.15
U22.9 DDR3 PLL clock A DDR3_CLKA_P J21 —
U22.10 DDR3 PLL clock A DDR3_CLKA_N J20 —
U22.13 DDR3 PLL clock B DDR3_CLKB_P N24 —
U22.14 DDR3 PLL clock B DDR3_CLKB_N N23 —
U22.17 DDR3 PLL clock C DDR3_CLKC_P M22 —
U22.18 DDR3 PLL clock C DDR3_CLKC_N M21 —
U22.21 DDR3 PLL clock D DDR3_CLKD_P R23 —
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