R
February 11, 2000 (Version 1.8)
6-115
XC4000E and XC4000X Series Field Programmable Gate Arrays
6
XC4000E IOB Output Switching Characteristic Guidelines
Testing of switching parameters is modeled after testing methods specied by MIL-M-38510/605. All devices are 100%
functionally tested. Internal timing parameters are derived from measuring internal test patterns. Listed below are
representative values. For more specic, more precise, and worst-case guaranteed data, use the values reported by the
static timing analyzer (TRCE in the Xilinx Development System) and back-annotated to the simulation net list. These path
delays, provided as a guideline, have been extracted from the static timing analyzer report. All timing parameters assume
worst-case operating conditions (supply voltage and junction temperature). Values apply to all XC4000E devices unless
otherwise noted.
Speed Grade
-4
-3
-2
-1
Units
Description
Symbol
Min
Max
Min
Max
Min
Max
Min
Max
Propagation Delays (TTL Output Levels)
Clock (OK) to Pad, fast
slew-rate limited
Output (O) to Pad, fast
slew-rate limited
3-state to Pad hi-Z
(slew-rate independent)
3-state to Pad active
and valid, fast
slew-rate limited
TOKPOF
TOKPOS
TOPF
TOPS
TTSHZ
TTSONF
TTSONS
7.5
11.5
8.0
12.0
5.0
9.7
13.7
6.5
9.5
5.5
8.5
4.2
8.1
11.1
4.5
7.0
4.8
7.3
3.8
7.3
9.8
3.0
5.0
3.2
5.2
3.0
6.8
8.8
ns
Propagation Delays (CMOS Output Levels)
Clock (OK) to Pad, fast
slew-rate limited
Output (O) to Pad, fast
slew-rate limited
3-state to Pad hi-Z
(slew-rate independent)
3-state to Pad active
and valid, fast
slew-rate limited
TOKPOFC
TOKPOSC
TOPFC
TOPSC
TTSHZC
TTSONFC
TTSONSC
9.5
13.5
10.0
14.0
5.2
9.1
13.1
7.8
11.6
9.7
13.4
4.3
7.6
11.4
7.0
10.4
8.7
12.1
3.9
6.8
10.2
4.0
7.0
4.0
6.0
3.9
6.8
8.8
ns
Note 1:
Output timing is measured at pin threshold, with 50pF external capacitive loads (incl. test xture). Slew-rate limited output
rise/fall times are approximately two times longer than fast output rise/fall times. For the effect of capacitive loads on ground
bounce, see the “Additional XC4000 Data” section of the Programmable Logic Data Book.
Note 2:
Voltage levels of unused pads, bonded or unbonded, must be valid logic levels. Each can be congured with the internal
pull-up (default) or pull-down resistor, or congured as a driven output, or can be driven from an external source.