R
Functional Description
Left-/Right-Half BUFGMUX
Top/Bottom (Global) BUFGMUX
CLK Switch
Matrix
CLK Switch
Matrix
BUFGMUX
O
BUFGMUX
O
S
S
I0
I0
0
1
0
1
I1
I1
I0
I1
I0
I1
0
1
0
1
O
O
S
S
LHCLK or
RHCLK input
1st GCLK pin
1st DCM output
Double Line
Double Line
DCM output*
*(XC3S1200E and
and XC3S1600E only)
2nd DCM output
2nd GCLK pin
DS312-2_16_022505
Figure 43: Clock Switch Matrix to BUFGMUX Pair Connectivity
The four quadrants of the device are:
Quadrant Clock Routing
•
•
•
•
Top Right (TR)
Bottom Right (BR)
Bottom Left (BL)
Top Left (TL)
The clock routing within the FPGA is quadrant-based, as
shown in Figure 42. Each clock quadrant supports eight
total clock signals, labeled ‘A’ through ‘H’ in Table 36 and
Figure 44. The clock source for an individual clock line orig-
inates either from a global BUFGMUX element along the
top and bottom edges or from a BUFGMUX element along
the associated edge, as shown in Figure 44. The clock lines
feed the synchronous resource elements (CLBs, IOBs,
block RAM, multipliers, and DCMs) within the quadrant.
Note that the quadrant clock notation (TR, BR, BL, TL) is
separate from that used for similar IOB placement con-
straints.
DS312-2 (v1.1) March 21, 2005
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Advance Product Specification
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