TIBPLS506AC Datasheet, PDF (11/16 Pages) Texas Instruments – 13 × 97 × 8 FIELD-PROGRAMMABLE LOGIC SEQUENCER

TIBPLS506AC
13 × 97 × 8 FIELD-PROGRAMMABLE LOGIC SEQUENCER
SRPS003C – D3090, DECEMBER 1987 – REVISED NOVEMBER 1995
OR term loading
As shown in Figure 3 and by the f_max calculations, f_max is affected by the number of terms connected to each
OR array line. Theoretically, f_max is calculated as:
) ^{fmax =} tsu
1
tpd CLK to Q
Since the setup time (input or feedback to S/R↓) varies with the number of terms connected to each OR array
line, (due to capacitance loading) f_maxwill also vary. Figure 3 illustrates the relationship between the number of
terms connected per OR line and the setup time.
Use Figure 3 to determine the worst-case setup time for a particular application. Identify the OR array line with
the maximum number of terms connected. Count the number of terms and use the graph to determine the setup
time.
WORST-CASE SETUP TIME
(input or feedback to SR↓)
vs
”OR” TERM LOAD
20
VCC = 4.75 V
19 ^{TA = 75°C}
18
17
16
15
14
13
12
11
10
0
20
40
60
80
100
Maximum Number of OR Terms Connected
Figure 3
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