74VHC238
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
HIGH NOISE IMMUNITY:
V
NIH
= V
NIL
= 28% V
CC
(MIN.)
POWER DOWN PROTECTION ON INPUTS
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 8 mA (MIN)
BALANCED PROPAGATION DELAYS:
t
PLH
≅
t
PHL
OPERATING VOLTAGE RANGE:
V
CC
(OPR) = 2V 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 74VHC238 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.
If 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
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Tree 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 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.
All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
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T&R
74VHC238MTR
74VHC238TTR
November 2004
Rev. 4
1/12
74VHC238
Table 4: Absolute Maximum Ratings
Symbol
V
CC
V
I
V
O
I
IK
I
OK
I
O
T
stg
T
L
Supply Voltage
DC Input Voltage
DC Output Voltage
DC Input Diode Current
DC Output Diode Current
DC Output Current
Storage Temperature
Lead Temperature (10 sec)
Parameter
Value
-0.5 to +7.0
-0.5 to +7.0
-0.5 to V
CC
+ 0.5
- 20
±
20
±
25
±
75
-65 to +150
300
Unit
V
V
V
mA
mA
mA
mA
°C
°C
I
CC
or I
GND
DC V
CC
or Ground Current
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is
not implied
Table 5: Recommended Operating Conditions
Symbol
V
CC
V
I
V
O
T
op
dt/dv
Supply Voltage
Input Voltage
Output Voltage
Operating Temperature
Input Rise and Fall Time (note 1) (V
CC
= 3.3
±
0.3V)
(V
CC
= 5.0
±
0.5V)
Parameter
1) V
IN
from 30% to 70% of V
CC
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t(
O
-
s
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Value
2 to 5.5
0 to 5.5
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Unit
V
V
V
°C
ns/V
0 to V
CC
0 to 100
0 to 20
-55 to 125
3/12
74VHC238
Table 6: DC Specifications
Test Condition
Symbol
Parameter
V
CC
(V)
2.0
3.0 to
5.5
2.0
3.0 to
5.5
2.0
3.0
4.5
3.0
4.5
V
OL
Low Level Output
Voltage
2.0
3.0
4.5
3.0
4.5
I
I
I
CC
Input Leakage
Current
Quiescent Supply
Current
0 to
5.5
5.5
I
O
=-50
µA
I
O
=-50
µA
I
O
=-50
µA
I
O
=-4 mA
I
O
=-8 mA
I
O
=50
µA
I
O
=50
µA
I
O
=50
µA
I
O
=4 mA
I
O
=8 mA
V
I
= 5.5V or GND
V
I
= V
CC
or GND
T
A
= 25°C
Min.
1.5
0.7V
CC
0.5
0.3V
CC
1.9
2.9
4.4
2.58
3.94
0.0
0.0
0.0
0.1
0.1
0.1
2.0
3.0
4.5
1.9
2.9
4.4
2.48
3.8
0.1
Typ.
Max.
Value
-40 to 85°C
Min.
1.5
0.7V
CC
0.5
0.3V
CC
1.9
2.9
4.4
2.4
Max.
-55 to 125°C
Min.
1.5
0.7V
CC
0.5
0.3V
CC
V
V
Max.
Unit
V
IH
High Level Input
Voltage
Low Level Input
Voltage
High Level Output
Voltage
V
IL
V
OH
Table 7: AC Electrical Characteristics
(Input t
r
= t
f
= 3ns)
Symbol
Parameter
t
PLH
t
PHL
t
PLH
t
PHL
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b
Propagation Delay
Time
A, B, C, to Y
ro
P
e
V
CC
(V)
3.3
(*)
3.3
(*)
5.0
(**)
5.0
(**)
3.3
(*)
3.3
(*)
5.0
(**)
5.0
(**)
Test Condition
C
L
(pF)
15
50
15
50
15
50
15
50
15
50
15
50
T
A
= 25°C
Min.
Typ.
8.0
10.5
5.5
7.0
8.1
10.6
5.4
6.9
8.1
10.6
5.7
7.2
Max.
12.3
15.8
8.1
10.1
12.8
16.3
8.1
10.1
12.3
15.8
8.1
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uc
d
)-
(s
t
b
O
so
0.36
0.36
±
0.1
4
te
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0.1
0.1
r
P
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V
V
0.1
0.1
0.1
0.44
0.44
±
1
40
0.55
0.55
±
1
40
µA
µA
Value
-40 to 85°C
Min.
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Max.
14.5
18.0
9.5
11.5
15.0
18.5
9.5
11.5
14.5
18.0
9.5
11.5
-55 to 125°C
Min.
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Max.
14.5
18.0
9.5
11.5
15.0
18.5
9.5
11.5
14.5
18.0
9.5
11.5
ns
ns
ns
Unit
Propagation Delay
Time
G1 to Y
t
PLH
t
PHL
Propagation Delay
Time
G2A, G2B to Y
3.3
(*)
3.3
(*)
5.0
(**)
5.0
(**)
(*) Voltage range is 3.3V
±
0.3V
(**) Voltage range is 5.0V
±
0.5V
4/12
74VHC238
Table 8: Capacitive Characteristics
Test Condition
Symbol
Parameter
T
A
= 25°C
Min.
C
IN
C
PD
Input Capacitance
Power Dissipation
Capacitance
(note 1)
Typ.
4
18
Max.
10
Value
-40 to 85°C
Min.
Max.
10
-55 to 125°C
Min.
Max.
10
pF
pF
Unit
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
Figure 4: Test Circuit
C
L
=15/50pF or equivalent (includes jig and probe capacitance)
R
T
= Z
OUT
of pulse generator (typically 50Ω)
Figure 5: Waveform - Propagation Delays For Inverting Outputs
(f=1MHz; 50% duty cycle)
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