User guide

56 www.xilinx.com Spartan-6 FPGA Configuration User Guide
UG380 (v2.7) October 29, 2014
Chapter 2: Configuration Interface Basics
Figure 2-23 shows the basic multi-drop flyby topology for one CCLK driver and two CCLK
receivers. The stub at CCLK input 1 has a length constraint.
Figure 2-24 shows the multi-drop flyby topology for one CCLK driver and more than two
CCLK receivers (four in this example). All CCLK inputs except input 4 have length
constraints.
X-Ref Target - Figure 2-23
Figure 2-23: Multi-Drop: One CCLK Output, Two CCLK Inputs
CCLK
Output
Z
0
(50Ω)
CCLK
Input 2
Z
0
(50Ω)
CCLK
Input 1
Z
0
(50Ω)
2 x Z
0
(100Ω)
2 x Z
0
(100Ω)
V
CCO_2
Z
0
(50Ω)
Length < 8 mm
UG380_c2_22_062510
X-Ref Target - Figure 2-24
Figure 2-24: Multi-Drop: One CCLK Output, More Than Two CCLK Inputs
CCLK
Output
Z
0
(50Ω)
CCLK
Input 4
Z
0
(50Ω)
2 x Z
0
(100Ω)
2 x Z
0
(100Ω)
V
CCO_2
Z
0
(50Ω)
Z
0
(50Ω)
CCLK
Input 2
length < 8 mm
Z
0
(50Ω)
Z
0
(50Ω)
CCLK
Input 3
length < 8 mm
Z
0
(50Ω)
Z
0
(50Ω)
CCLK
Input 1
Length < 8 mm
UG380_c2_23_062510