Philips Semiconductors
74HC244; 74HCT244
Octal buffer/line driver; 3-state
Table 10: Dynamic characteristics type 74HCT244
…continued
GND = 0 V; t
r
= t
f
= 6 ns; C
L
= 50 pF unless otherwise specified; for test circuit see
Figure 8.
Symbol Parameter
T
amb
=
−40 °C
to +85
°C
t
PHL
,
t
PLH
t
PZH
,
t
PZL
t
PHZ
,
t
PLZ
t
THL
,
t
TLH
t
PHL
,
t
PLH
t
PZH
,
t
PZL
t
PHZ
,
t
PLZ
t
THL
,
t
TLH
[1]
Conditions
Min
-
-
-
-
Typ
-
-
-
-
Max
28
38
31
15
Unit
ns
ns
ns
ns
propagation delay nAn to nYn V
CC
= 4.5 V; see
3-state output enable time
nOE to nYn
3-state output disable time
nOE to nYn
output transition time
V
CC
= 4.5 V; see
V
CC
= 4.5 V; see
V
CC
= 4.5 V; see
T
amb
=
−40 °C
to +125
°C
propagation delay nAn to nYn V
CC
= 4.5 V; see
3-state output enable time
nOE to nYn
3-state output disable time
nOE to nYn
output transition time
V
CC
= 4.5 V; see
V
CC
= 4.5 V; see
V
CC
= 4.5 V; see
-
-
-
-
-
-
-
-
33
45
38
18
ns
ns
ns
ns
C
PD
is used to determine the dynamic power dissipation (P
D
in
µW):
P
D
= C
PD
×
V
CC2
×
f
i
×
N +
∑(C
L
×
V
CC2
×
f
o
) where:
f
i
= input frequency in MHz;
f
o
= output frequency in MHz;
C
L
= output load capacitance in pF;
V
CC
= supply voltage in V;
N = number of inputs switching;
∑(C
L
×
V
CC2
×
f
o
) = sum of outputs.
12. Waveforms
V
I
nAn input
GND
t
PHL
V
OH
nYn output
V
OL
t
THL
90 %
V
M
10 %
t
TLH
001aae013
V
M
V
M
t
PLH
V
M
Measurement points are given in
V
OL
and V
OH
are typical voltage output drop that occur with the output load.
Fig 6. Propagation delay input (1An, 2An) to output (1Yn, 2Yn) and transition time output
(nYn)
74HC_HCT244_3
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
Product data sheet
Rev. 03 — 22 December 2005
12 of 22
PHILIPS [ NXP SEMICONDUCTORS ]
