xc3s1400an Xilinx Corp., xc3s1400an Datasheet - Page 49

• Manufacturer Part Number: xc3s1400an
• Description: Spartan-3an Fpga Family Data Sheet
• Manufacturer: Xilinx Corp.

Digital Frequency Synthesizer (DFS)
Table 39: Recommended Operating Conditions for the DFS
Table 40: Switching Characteristics for the DFS
DS557-3 (v3.1) June 2, 2008
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 Duty cycle precision for the CLKFX and CLKFX180 outputs,
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
(4,5)
CLKIN_FREQ_FX
Symbol
R
(5)
(2,3)
(2)
Frequency for the CLKFX and CLKFX180 outputs
Period jitter at 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
(3)
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
CLKIN
20 MHz
< 150 MHz
> 150 MHz
Device
All
All
All
All
All
0.200
Min
–
–
–
www.xilinx.com/support/documentation
±[1% of
CLKFX
period
+ 100]
Use the Spartan-3A Jitter Calculator:
Min
Typ
DC and Switching Characteristics
–
–
–
5
/data_sheets/s3a_jitter_calc.zip
-5
±300
±150
Max
Speed Grade
-5
333
±1
±[1% of
±[1% of
±[1% of
CLKFX
CLKFX
CLKFX
period
+ 200]
period
+ 350]
period
+ 200]
±200
Max
Max
350
Speed Grade
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
37.
Units
MHz
Units
ps
ps
ns
MHz
ps
ps
ps
ps
ps
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