Spartan-3 FPGA Family: DC and Switching Characteristics
DS099 (v3.1) June 27, 2013
Product Specification
95
Digital Frequency Synthesizer (DFS)
Lock Time
LOCK_DLL
When using the DLL alone:
The time from deassertion at
the DCM’s Reset input to the
rising transition at its
LOCKED output. When the
DCM is locked, the CLKIN and
CLKFB signals are in phase
18 MHz
≤ FCLKIN ≤ 30 MHz
All
–
2.88
–
2.88
ms
30 MHz
< FCLKIN ≤ 40 MHz
–
2.16
–
2.16
ms
40 MHz
< FCLKIN ≤ 50 MHz
–
1.20
–
1.20
ms
50 MHz
< FCLKIN ≤ 60 MHz
–
0.60
–
0.60
ms
FCLKIN > 60 MHz
–
0.48
–
0.48
ms
Delay Lines
DCM_TAP
Delay tap resolution
All
30.0
60.0
30.0
60.0
ps
Notes:
1.
The numbers in this table are based on the operating conditions set forth in
Table 32 and
Table 58.2.
DLL specifications apply when any of the DLL outputs (CLK0, CLK90, CLK180, CLK270, CLK2X, CLK2X180, or CLKDV) are in use.
3.
DLL feedback using the CLK2X output. For all other Spartan-3 devices, use feedback from the CLK0 output (instead of the CLK2X output)
and set the CLK_FEEDBACK attribute to 1X.
4.
Indicates the maximum amount of output jitter that the DCM adds to the jitter on the CLKIN input.
5.
This specification only applies if the attribute DUTY_CYCLE_CORRECTION = TRUE.
Table 60: Recommended Operating Conditions for the DFS
Symbol
Description
Frequency
Mode
Speed Grade
Units
-5
-4
MinMax
Input Frequency Ranges(2) FCLKIN
CLKIN_FREQ_FX
Frequency for the CLKIN input
All
1
280
1
280
MHz
Input Clock Jitter Tolerance(3)
CLKIN_CYC_JITT_FX_LF
Cycle-to-cycle jitter at the CLKIN
input
Low
–
±300
–
±300
ps
CLKIN_CYC_JITT_FX_HF
High
–
±150
–
±150
ps
CLKIN_PER_JITT_FX
Period jitter at the CLKIN input
All
–
±1
–
±1ns
Notes:
1.
DFS specifications apply when either of the DFS outputs (CLKFX or CLKFX180) are used.
2.
If both DFS and DLL outputs are used on the same DCM, follow the more restrictive CLKIN_FREQ_DLL specifications in
Table 58.
3.
CLKIN input jitter beyond these limits may cause the DCM to lose lock.
Table 59: Switching Characteristics for the DLL (Cont’d)
Symbol
Description
Frequency Mode /
FCLKIN Range
Device
Speed Grade
Units
-5
-4
Min
Max
Min
Max