74VHCT238A
3 TO 8 LINE DECODER
s
s
s
s
s
s
s
s
s
HIGH SPEED: t
PD
= 5.5 ns (TYP.) at V
CC
= 5V
LOW POWER DISSIPATION:
I
CC
= 4
µA
(MAX.) at T
A
=25°C
COMPATIBLE WITH TTL OUTPUTS:
V
IH
= 2V (MIN.), V
IL
= 0.8V (MAX)
POWER DOWN PROTECTION ON INPUTS
& OUTPUTS
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 8 mA (MIN)
BALANCED PROPAGATION DELAYS:
t
PLH
≅
t
PHL
OPERATING VOLTAGE RANGE:
V
CC
(OPR) = 4.5V to 5.5V
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 238
IMPROVED LATCH-UP IMMUNITY
SOP
TSSOP
Table 1: Order Codes
PACKAGE
SOP
TSSOP
DESCRIPTION
The 74VHCT238A is an advanced high-speed
CMOS 3 TO 8 LINE DECODER fabricated with
sub-micron silicon gate and double-layer metal
wiring C
2
MOS technology.
When the device is enabled, 3 binary select inputs
(A, B, and C) determine which one of the outputs
will go high. If enable input G1 is held low or either
G2A or G2B is held high, decoding function is
inhibited and all the 8 outputs go to low.
Figure 1: Pin Connection And IEC Logic Symbols
te
le
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b
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ro
P
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t(
The three enable inputs are provided to ease
cascade connection and application of address
decoders for memory systems.
Power down protection is provided on all inputs
and outputs and 0 to 7V can be accepted on
inputs with no regard to the supply voltage. This
device can be used to interface 5V to 3V since all
inputs are equipped with TTL threshold.
All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
O
-
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b
t
le
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T&R
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74VHCT238AMTR
74VHCT238ATTR
December 2004
Rev. 3
1/12
74VHCT238A
Table 4: Absolute Maximum Ratings
Symbol
V
CC
V
I
V
O
V
O
I
IK
I
OK
I
O
Supply Voltage
DC Input Voltage
DC Output Voltage (see note 1)
DC Output Voltage (see note 2)
DC Input Diode Current
DC Output Diode Current
DC Output Current
Parameter
Value
-0.5 to +7.0
-0.5 to +7.0
-0.5 to +7.0
-0.5 to V
CC
+ 0.5
- 20
±
20
±
25
±
50
-65 to +150
300
Unit
V
V
V
V
mA
mA
mA
I
CC
or I
GND
DC V
CC
or Ground Current
Storage Temperature
T
stg
T
L
Lead Temperature (10 sec)
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is
not implied
1) V
CC
= 0V
2) High or Low State
Table 5: Recommended Operating Conditions
Symbol
V
CC
V
I
V
O
V
O
T
op
dt/dv
Supply Voltage
Input Voltage
Output Voltage (see note 1)
Output Voltage (see note 2)
Operating Temperature
Parameter
Input Rise and Fall Time (see note 3) (V
CC
= 5.0
±
0.5V)
1) V
CC
= 0V
2) High or Low State
3) V
IN
from 0.8V to 2V
te
le
so
b
O
ro
P
uc
d
)-
(s
t
b
O
so
t
le
r
P
e
Value
4.5 to 5.5
0 to 5.5
0 to 5.5
0 to V
CC
-55 to 125
0 to 20
du
o
s)
t(
c
mA
°C
°C
Unit
V
V
V
V
°C
ns/V
3/12
74VHCT238A
Table 6: DC Specifications
Test Condition
Symbol
Parameter
V
CC
(V)
4.5 to
5.5
4.5 to
5.5
4.5
4.5
4.5
4.5
0 to
5.5
5.5
5.5
0
I
O
=-50
µA
I
O
=-8 mA
I
O
=50
µA
I
O
=8 mA
V
I
= 5.5V or GND
V
I
= V
CC
or GND
One Input at 3.4V,
other input at V
CC
or GND
V
OUT
= 5.5V
T
A
= 25°C
Min.
2
0.8
4.4
3.94
0.0
0.1
0.36
±
0.1
4
1.35
4.5
4.4
3.8
0.1
0.44
±
1.0
Typ.
Max.
Value
-40 to 85°C
Min.
2
0.8
4.4
3.7
0.1
0.55
Max.
-55 to 125°C
Min.
2
0.8
Max.
V
V
V
Unit
V
IH
V
IL
V
OH
V
OL
I
I
I
CC
+I
CC
High Level Input
Voltage
Low Level Input
Voltage
High Level Output
Voltage
Low Level Output
Voltage
Input Leakage
Current
Quiescent Supply
Current
Additional Worst
Case Supply
Current
Output Leakage
Current
I
OPD
Table 7: AC Electrical Characteristics
(Input t
r
= t
f
= 3ns)
Test Condition
Symbol
Parameter
V
CC
(*)
C
L
(V)
(pF)
t
PLH
t
PHL
t
PLH
t
PHL
t
PLH
t
PHL
Propagation Delay
Time A,B,C to Y
Propagation Delay
Time G1 to Y
Propagation Delay
Time
G2A, G2B to Y
(*) Voltage range is 5.0V
±
0.5V
Table 8: Capacitive Characteristics
Test Condition
Symbol
Parameter
Min.
C
IN
C
PD
Input Capacitance
Power Dissipation
Capacitance
(note 1)
T
A
= 25°C
Typ.
6
37
Max.
10
Value
-40 to 85°C
Min.
Max.
10
-55 to 125°C
Min.
Max.
10
pF
pF
Unit
te
le
so
b
O
r
P
5.0
5.0
5.0
5.0
5.0
5.0
od
15
50
15
50
15
50
uc
)-
(s
t
b
O
Typ.
5.5
7.0
5.4
6.9
5.7
7.2
so
0.5
Max.
8.1
10.1
8.1
10.1
8.1
10.1
t
le
Min.
1.0
1.0
1.0
1.0
1.0
1.0
ro
P
e
40
1.5
5.0
du
±
1.0
40
1.5
5.0
s)
t(
c
V
µA
µA
mA
µA
Value
-40 to 85°C
Max.
9.5
11.5
9.5
11.5
9.5
11.5
-55 to 125°C
Min.
1.0
1.0
1.0
1.0
1.0
1.0
Max.
9.5
11.5
9.5
11.5
9.5
11.5
ns
ns
ns
Unit
T
A
= 25°C
Min.
1) C
PD
is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without
load. (Refer to Test Circuit). Average operating current can be obtained by the following equation. I
CC(opr)
= C
PD
x V
CC
x f
IN
+ I
CC
4/12
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