NXP Semiconductors
74HC238; 74HCT238
3-to-8 line decoder/demultiplexer
Table 7.
Dynamic characteristics
GND = 0 V; test circuit see
Figure 8.
Symbol Parameter
Conditions
Min
74HCT238
t
pd
propagation delay An to Yn; see
V
CC
= 4.5 V
V
CC
= 5.0 V; C
L
= 15 pF
E3 to Yn; see
V
CC
= 4.5 V
V
CC
= 5.0 V; C
L
= 15 pF
En to Yn or see
V
CC
= 4.5 V
V
CC
= 5.0 V; C
L
= 15 pF
t
t
C
PD
transition time
power dissipation
capacitance
V
CC
= 4.5 V;
see
and
per package;
V
I
= GND to V
CC
−
1.5 V
25
°C
Typ
Max
−40 °C
to +125
°C
Max
(85
°C)
Max
Unit
(125
°C)
-
-
-
-
-
-
-
-
19
18
20
20
20
21
7
76
35
-
37
-
35
-
15
-
44
-
46
-
44
-
19
-
53
-
56
-
53
-
22
-
ns
ns
ns
ns
ns
ns
ns
pF
[1]
[2]
[3]
t
pd
is the same as t
PHL
and t
PLH
.
t
t
is the same as t
THL
and t
TLH
.
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.
11. Waveforms
An, E3 input
V
M
t
PHL
V
Y
t
PLH
V
M
V
X
t
THL
t
TLH
001aag757
Yn output
Measurement points are given in
V
OL
and V
OH
are typical voltage output levels that occur with the output load.
Fig 6. Input (An, E3) to output (Yn) propagation delays and output transition times
74HC_HCT238_3
© NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 03 — 16 July 2007
8 of 18
PHILIPS [ NXP SEMICONDUCTORS ]
