
Spartan-3 FPGA Family: DC and Switching Characteristics
DS099 (v3.1) June 27, 2013
Product Specification
76
Table 46: Timing for the IOB Three-State Path
Symbol
Description
Conditions
Device
Speed Grade
Units
-5
-4
Synchronous Output Enable/Disable Times
TIOCKHZ
Time from the active transition at the
OTCLK input of the Three-state Flip-Flop
(TFF) to when the Output pin enters the
high-impedance state
LVCMOS25, 12 mA
output drive, Fast slew
rate
All
0.74
0.85
ns
Time from the active transition at TFF’s
OTCLK input to when the Output pin drives
valid data
All
0.72
0.82
ns
Asynchronous Output Enable/Disable Times
TGTS
Time from asserting the Global Three State
(GTS) net to when the Output pin enters the
high-impedance state
LVCMOS25, 12 mA
output drive, Fast slew
rate
XC3S200
XC3S400
7.71
8.87
ns
XC3S50
XC3S1000
XC3S1500
XC3S2000
XC3S4000
XC3S5000
8.38
9.63
ns
Set/Reset Times
TIOSRHZ
Time from asserting TFF’s SR input to when
the Output pin enters a high-impedance
state
LVCMOS25, 12 mA
output drive, Fast slew
rate
All
1.55
1.78
ns
Time from asserting TFF’s SR input at TFF
to when the Output pin drives valid data
XC3S200
XC3S400
2.24
2.57
ns
XC3S50
XC3S1000
XC3S1500
XC3S2000
XC3S4000
XC3S5000
2.91
3.34
ns
Notes:
1.
The numbers in this table are tested using the methodology presented in
Table 48 and are based on the operating conditions set forth in
2.
This time requires adjustment whenever a signal standard other than LVCMOS25 with 12 mA drive and Fast slew rate is assigned to the data
Output. When this is true, add the appropriate Output adjustment from
Table 47.
3.
For minimums, use the values reported by the Xilinx timing analyzer.
Table 47: Output Timing Adjustments for IOB
Convert Output Time from LVCMOS25 with 12mA Drive and Fast Slew Rate to the
Following Signal Standard (IOSTANDARD)
Add the Adjustment Below
Units
Speed Grade
-5
-4
Single-Ended Standards
GTL
00.02
ns
GTL_DCI
0.13
0.15
ns
GTLP
0.03
0.04
ns
GTLP_DCI
0.23
0.27
ns
HSLVDCI_15
1.51
1.74
ns
HSLVDCI_18
0.81
0.94
ns