28 www.xilinx.com Virtex-5 FPGA ML561 User Guide
UG199 (v1.2.1) June 15, 2009
Chapter 3: Hardware Description
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200 MHz LVPECL Clock
The 200 MHz LVPECL clock source is an Epson EG-2121CA200M-PCHS oscillator (Y1)
with a differential output. The oscillator runs at 200 MHz ± 100 PPM with an operating
voltage of 2.5V ±5%. This output is fed into an ICS853006 LVPECL buffer for generating a
separate differential copy for each FPGA as well as a test point (P59).
SMA Clock
Two SMA connectors are provided for the input of an off-board differential clock (J19 and
J20). A differential clock buffer (ICS853006) is used on the board (U17 and U18) to generate
four LVPECL copies of the differential clock signal, one for each FPGA along with a probe
point (P40) for testing. The traces from the buffer are routed as a differential pair to each
FPGA where they are terminated with 100Ω differential termination.
33 MHz Clock
A single-ended 33 MHz Epson SG-8002CA oscillator is provided on the board (Y2) for
testing purposes. Four copies of this clock are generated using a clock buffer (ICS8304) on
the board, one per FPGA along with a probe point for testing (P41).
The application using this clock source as an input to the PLL on the Virtex-5 device has
not yet been fully verified.
Table 3-10: FPGA 200 MHz IDELAY Reference Clock Source
FPGA # Signal Name
1 DIRECT_CLK_TO_FPGA1_P
1 DIRECT_CLK_TO_FPGA1_N
2 DIRECT_CLK_TO_FPGA2_P
2 DIRECT_CLK_TO_FPGA2_N
3 DIRECT_CLK_TO_FPGA3_P
3 DIRECT_CLK_TO_FPGA3_N
Table 3-11: FPGA External Clock Sources
FPGA # Signal Name
1 EXT_CLK_TO_FPGA1_P
1 EXT_CLK_TO_FPGA1_N
2 EXT_CLK_TO_FPGA2_P
2 EXT_CLK_TO_FPGA2_N
3 EXT_CLK_TO_FPGA3_P
3 EXT_CLK_TO_FPGA3_N
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