XC2V8000-5BF957C Xilinx, Inc., XC2V8000-5BF957C Datasheet - Page 35

• Manufacturer Part Number: XC2V8000-5BF957C
• Description: Virtex-II 1.5V Field-Programmable Gate Array
• Manufacturer: Xilinx, Inc.

Virtex-II 1.5V Field-Programmable Gate Arrays
Global Clock Multiplexer Buffers
Virtex-II devices have 16 clock input pins that can also be
used as regular user I/Os. Eight clock pads are on the top
edge of the device, in the middle of the array, and eight are
on the bottom edge, as illustrated in
The global clock multiplexer buffer represents the input to
dedicated low-skew clock tree distribution in Virtex-II
devices. Like the clock pads, eight global clock multiplexer
buffers are on the top edge of the device and eight are on
the bottom edge.
Each global clock buffer can either be driven by the clock
pad to distribute a clock directly to the device, or driven by
the Digital Clock Manager (DCM), discussed in
Clock Manager (DCM), page
Module 2 of 4
28
Figure 37: Virtex-II Clock Pads
Virtex-II
Device
8 clock pads
8 clock pads
NW
SW
30. Each global clock buffer
8 BUFGMUX
16 Clocks
8 BUFGMUX
Figure
Figure 39: Virtex-II Clock Distribution
37.
DS031_42_101000
SE
NE
Digital
www.xilinx.com
1-800-255-7778
NW
SW
can also be driven by local interconnects. The DCM has
clock output(s) that can be connected to global clock buffer
inputs, as shown in
Global clock buffers are used to distribute the clock to some
or all synchronous logic elements (such as registers in
CLBs and IOBs, and SelectRAM blocks.
Eight global clocks can be used in each quadrant of the
Virtex-II device. Designers should consider the clock distri-
bution detail of the device prior to pin-locking and floorplan-
ning (see the Virtex-II User Guide).
Figure 39
8
8
Figure 38: Virtex-II Clock Distribution Configurations
8 BUFGMUX
8 BUFGMUX
16 Clocks
Clock Distribution
shows clock distribution in Virtex-II devices.
Buffer
Clock
Clock
Pad
I
0
Figure
8
8
38.
DS031-2 (v1.8) October 12, 2001
Advance Product Specification
DS031_45_120200
Clock Distribution
8 max
SE
NE
CLKOUT
CLKIN
Buffer
DS031_43_101000
DCM
Clock
Clock
Pad
I
0
R