DS162 Datasheet, PDF (68/73 Pages) Xilinx, Inc – Advance Product Specification

Spartan-6 FPGA Data Sheet: DC and Switching Characteristics
Source-Synchronous Switching Characteristics
The parameters in this section provide the necessary values for calculating timing budgets for Spartan-6 FPGA
source-synchronous transmitter and receiver data-valid windows.
Table 75: Duty Cycle Distortion and Clock-Tree Skew
Symbol
T_{DCD_CLK}
T_CKSKEW
T_{DCD_BUFIO2}
T_BUFIOSKEW
Description
Device⁽¹⁾
-4
Global Clock Tree Duty Cycle Distortion⁽²⁾ LX Family
N/A
Global Clock Tree Skew⁽³⁾
LXT Family
0.20
XC6SLX4
N/A
XC6SLX9
N/A
XC6SLX16
N/A
XC6SLX25
N/A
XC6SLX25T
0.26
XC6SLX45
N/A
XC6SLX45T
0.20
XC6SLX75
N/A
XC6SLX75T
0.56
XC6SLX100
N/A
XC6SLX100T
0.22
XC6SLX150
N/A
XC6SLX150T
0.39
I/O clock tree duty cycle distortion
LX Family
N/A
LXT Family
0.25
I/O clock tree skew across one clock
region
LX Family
LXT Family
N/A
0.06
Speed Grade
-3
-2
0.20
0.20
0.20
0.20
0.16
0.16
0.16
0.16
0.15
0.15
0.26
0.26
0.26
0.26
0.20
0.20
0.20
0.20
0.56
0.56
0.56
0.56
0.22
0.22
0.22
0.22
0.48
0.48
0.48
0.48
0.25
0.25
0.25
0.25
0.06
0.06
0.06
0.06
Units
-1L
ns
N/A
ns
ns
ns
ns
N/A
ns
ns
N/A
ns
ns
N/A
ns
ns
N/A
ns
ns
N/A
ns
ns
N/A
ns
N/A
ns
Notes:
1. LX devices are not available with a -4 speed grade; LXT devices are not available with a -1L speed grade.
2. These parameters represent the worst-case duty cycle distortion observable at the pins of the device using LVDS output buffers. For cases where
other I/O standards are used, IBIS can be used to calculate any additional duty cycle distortion that might be caused by asymmetrical rise/fall times.
3. The T_CKSKEW value represents the worst-case clock-tree skew observable between sequential I/O elements. Significantly less clock-tree skew exists
for I/O registers that are close to each other and fed by the same or adjacent clock-tree branches. Use the Xilinx FPGA Editor and Timing Analyzer
tools to evaluate clock skew specific to your application.
DS162 (v1.9) August 23, 2010
www.xilinx.com
Advance Product Specification
68