www.fairchildsemi.com 4
74F251A
AC Electrical Characteristics
Symbol Parameter
T
A
= +25°CT
A
= −55°C to +125°CT
A
= 0°C to +70°C
Units
V
CC
= +5.0V V
CC
= 5.0V V
CC
= 5.0V
C
L
= 50 pF C
L
= 50 pF C
L
= 50 pF
Min Typ Max Min Max Min Max
t
PLH
Propagation Delay 3.5 6.0 9.0 3.5 11.5 3.5 9.5
ns
t
PHL
S
n
to Z 3.25.07.53.28.03.27.5
t
PLH
Propagation Delay 4.5 7.5 10.5 3.5 14.0 4.5 12.5
ns
t
PHL
S
n
to Z 4.0 6.0 8.5 3.0 10.5 4.0 9.0
t
PLH
Propagation Delay 3.0 5.0 6.5 2.5 8.0 3.0 7.0
ns
t
PHL
I
n
to Z 1.52.54.01.56.01.55.0
t
PLH
Propagation Delay 3.5 5.0 7.0 2.5 9.0 2.5 8.0
ns
t
PHL
I
n
to Z 3.5 5.5 7.0 3.5 9.0 3.5 7.5
t
PZH
Output Enable Time 2.5 4.3 6.0 2.0 7.0 2.5 7.0
ns
t
PZL
OE to Z 2.54.36.02.57.52.56.5
t
PHZ
Output Disable Time 2.5 4.0 5.5 2.5 6.0 2.5 6.0
t
PLZ
OE to Z 1.53.04.51.55.01.54.5
t
PZH
Output Enable Time 3.5 5.0 7.0 3.0 8.5 3.0 7.5
ns
t
PZL
OE to Z 3.5 5.5 7.5 3.5 9.0 3.5 8.0
t
PHZ
Output Disable Time 2.0 3.8 5.5 2.0 5.5 2.0 5.5
t
PLZ
OE to Z 1.5 3.0 4.5 1.5 5.5 1.5 4.5
