XC3S50A Xilinx Corp., XC3S50A Datasheet - Page 47

• Manufacturer Part Number: XC3S50A
• Description: Spartan-3a Fpga Family Data Sheet
• Manufacturer: Xilinx Corp.

Digital Frequency Synthesizer (DFS)
Table 37: Recommended Operating Conditions for the DFS
Table 38: Switching Characteristics for the DFS
DS529-3 (v1.5) July 10, 2007
Product Specification
Notes:
1.
2.
3.
Output Frequency Ranges
CLKOUT_FREQ_FX
Output Clock Jitter
CLKOUT_PER_JITT_FX
Duty Cycle
CLKOUT_DUTY_CYCLE_FX
Phase Alignment
CLKOUT_PHASE_FX
CLKOUT_PHASE_FX180
Input Frequency Ranges
F
Input Clock Jitter Tolerance
CLKIN_CYC_JITT_FX_LF
CLKIN_CYC_JITT_FX_HF
CLKIN_PER_JITT_FX
CLKIN
DFS specifications apply when either of the DFS outputs (CLKFX or CLKFX180) are used.
If both DFS and DLL outputs are used on the same DCM, follow the more restrictive CLKIN_FREQ_DLL specifications in
CLKIN input jitter beyond these limits may cause the DCM to lose lock.
Symbol
(5,6)
CLKIN_FREQ_FX
Symbol
R
(6)
(3,4)
(2)
(2)
(3)
Frequency for the CLKFX and CLKFX180 outputs
Period jitter at the CLKFX and CLKFX180
outputs.
Duty cycle precision for the CLKFX and CLKFX180 outputs,
including the BUFGMUX and clock tree duty-cycle distortion
Phase offset between the DFS CLKFX output and the DLL CLK0
output when both the DFS and DLL are used
Phase offset between the DFS CLKFX180 output and the DLL
CLK0 output when both the DFS and DLL are used
Frequency for the CLKIN input
input, based on CLKFX output
frequency
Period jitter at the CLKIN input
Cycle-to-cycle jitter at the CLKIN
Description
Description
www.xilinx.com
F
F
CLKFX
CLKFX
> 20 MHz
≤
CLKIN
20 MHz
CLKIN
< 150 MHz
> 150 MHz
Device
All
All
All
All
All
0.200
Min
–
–
–
±[1% of
Use the Spartan-3A Jitter Calculator:
www.xilinx.com/bvdocs/publications/
CLKFX
+ 100]
DC and Switching Characteristics
period
Min
Typ
-5
5
–
–
–
±300
±150
Max
Speed Grade
333
±1
-5
s3a_jitter_calc.zip
±[1% of
±[1% of
±[1% of
CLKFX
CLKFX
CLKFX
period
+ 200]
period
+ 350]
period
+ 200]
±200
Max
Max
Speed Grade
350
0.200
Min
–
–
–
±[1% of
CLKFX
period
+ 100]
Min
Typ
–
–
–
5
-4
Table
-4
±300
±150
Max
333
±1
±[1% of
±[1% of
±[1% of
CLKFX
CLKFX
CLKFX
period
+ 200]
period
+ 350]
period
+ 200]
±200
Max
Max
320
35.
Units
MHz
Units
ps
ps
ns
MHz
ps
ps
ps
ps
ps
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