Page 1
74VHC238
3 TO 8 LINE DECODER
■ HIGH SPEED: t
■ LOW POWER DISSIPATION:
I
= 4 µA (MAX.) at TA=25°C
CC
■ HIGH NOISE IMMUNITY:
V
= V
NIH
■ POWER DOWN PROTECTION ON INPUTS
■ SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
■ BALANCED PROPAGATION DELAYS:
t
PLH
■ OPERATING VOLTAGE RANGE:
V
CC
■ PIN AND FUNCTION COMPATIBLE WITH
NIL
| = IOL = 8 mA (MIN)
≅ t
PHL
(OPR) = 2V to 5.5V
= 5.5 ns (TYP.) at VCC = 5V
PD
= 28% VCC (MIN.)
74 SERIES 238
■ IMPROVED LATCH-UP IMMUNITY
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 in put G1 is held low or either
G2A
or G2B is held high, decoding function is
inhibited and all the 8 outputs go to low.
TSSOPSOP
Table 1: Order Codes
PACKAGE T & R
SOP 74VHC238MTR
TSSOP 74VHC238TTR
Tree enable inpu ts 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 disc harge, giving
them 2KV ESD immunity and transient excess
voltage.
Figure 1: Pin Connection And IEC Logic Symbols
Rev. 4
1/12November 2004
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74VHC238
Figure 2: Input Equivalent Circuit Table 2: Pin Description
PIN N° SYMBOL NAME AND FUNCTION
1, 2, 3 A, B, C Address Inputs
4, 5 G2A
6 G1 Enable Input
15, 14, 13,
12, 1 1, 10, 9,
7
8 GND Ground (0V)
16 V
Table 3: Truth Table
, G2B Enable Inputs
Y0 to Y7 Outputs
CC
Positive Supply Voltage
INPUTS
ENABLE SELECT
G2B
X : Don’t ca re
G2A G1 C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
XXLXXXLLLLLLLL
XHXXXXLLLLLLLL
HXXXXXLLLLLLLL
LLHLLLHLLLLLLL
LLHLLHLHLLLLLL
LLHLHLLLHLLLLL
LLHLHHLLLHLLLL
LLHHLLLLLLHLLL
LLHHLHLLLLLHLL
LLHHHLLLLLLLHL
LLHHHHLLLLLLLH
OUTPUTS
Figure 3: Logic Diagram
This logi c di agram has not be used to est i m ate propaga tion delays
2/12
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74VHC238
Table 4: Absolute Maximum Ratings
Symbol Parameter Value Unit
V
V
V
I
I
OK
I
or I
I
CC
T
T
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 Parameter Value Unit
V
V
V
T
dt/dv
Supply Voltage
CC
DC Input Voltage
I
DC Output Voltage -0.5 to VCC + 0.5
O
DC Input Diode Current
IK
DC Output Diode Current
DC Output Current
O
DC VCC or Ground Current
GND
Storage Temperature
stg
Lead Temperature (10 sec)
L
Supply Voltage
CC
Input Voltage
I
Output Voltage 0 to V
O
Operating Temperature
op
Input Rise and Fall Time (note 1) (V
(V
= 3.3 ± 0.3V)
CC
= 5.0 ± 0.5V)
CC
-0.5 to +7.0 V
-0.5 to +7.0 V
- 20 mA
± 20 mA
± 25 mA
± 75 mA
-65 to +150 °C
300 °C
2 to 5.5 V
0 to 5.5 V
CC
-55 to 125 °C
0 to 100
0 to 20
ns/V
V
V
1) VIN from 30 % t o 70% of V
CC
3/12
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74VHC238
Table 6: DC Specifications
Symbol Parameter
V
V
V
High Level Input
IH
Voltage
V
Low Level Input
IL
Voltage
High Level Output
OH
Voltage
Low Level Output
OL
Voltage
I
Input Leakage
I
Current
I
Quiescent Supply
CC
Current
3.0 to
3.0 to
Test Condition Value
V
(V)
CC
T
A
Min. Typ. Max. Min. Max. Min. Max.
-40 to 85°C -55 to 125°C
= 25°C
2.0 1.5 1.5 1.5
5.5
0.7V
CC
0.7V
CC
0.7V
CC
2.0 0.5 0.5 0.5
5.5
2.0
3.0
4.5
3.0
4.5
2.0
3.0
4.5
3.0
4.5
0 to
VI = 5.5V or GND
5.5
V
5.5
IO=-50 µA
I
=-50 µA
O
=-50 µA
I
O
=-4 mA
I
O
=-8 mA
I
O
IO=50 µA
=50 µA
I
O
=50 µA
I
O
=4 mA
I
O
=8 mA
I
O
= VCC or GND
I
0.3V
CC
1.9 2.0 1.9 1.9
2.9 3.0 2.9 2.9
4.4 4.5 4.4 4.4
2.58 2.48 2.4
3.94 3.8 3.7
0.0 0.1 0.1 0.1
0.0 0.1 0.1 0.1
0.0 0.1 0.1 0.1
0.36 0.44 0.55
0.36 0.44 0.55
± 0.1 ± 1 ± 1 µA
44040µA
0.3V
CC
0.3V
CC
Unit
V
V
V
V
Table 7: AC Electrical Characteristics (Input t
Test Condition Value
Symbol Parameter
t
Propagation Delay
PLH
t
t
t
t
t
(*) Voltage range is 3.3V ± 0.3V
(**) Volt age range is 5.0V ±
Time
PHL
A, B, C, to Y
Propagation Delay
PLH
Time
PHL
G1 to Y
Propagation Delay
PLH
Time
PHL
G2A
, G2B to Y
0.5V
V
3.3
3.3
5.0
5.0
3.3
3.3
5.0
5.0
3.3
3.3
5.0
5.0
C
CC
(V)
L
(pF)
(*)
15 8.0 12.3 1.0 14.5 1.0 14.5
(*)
50 10.5 15.8 1.0 18.0 1.0 18.0
(**)
15 5.5 8.1 1.0 9.5 1.0 9.5
(**)
50 7.0 10.1 1.0 11.5 1.0 11.5
(*)
15 8.1 12.8 1.0 15.0 1.0 15.0
(*)
50 10.6 16.3 1.0 18.5 1.0 18.5
(**)
15 5.4 8.1 1.0 9.5 1.0 9.5
(**)
50 6.9 10.1 1.0 11.5 1.0 11.5
(*)
15 8.1 12.3 1.0 14.5 1.0 14.5
(*)
50 10.6 15.8 1.0 18.0 1.0 18.0
(**)
15 5.7 8.1 1.0 9.5 1.0 9.5
(**)
50 7.2 10.1 1.0 11.5 1.0 11.5
= tf = 3ns)
r
= 25°C
T
A
-40 to 85°C -55 to 125°C
Min. Typ. Max. Min. Max. Min. Max.
Unit
ns
ns
ns
4/12
Page 5
74VHC238
Table 8: Capacitive Characteristics
Test Condition Value
= 25°C
Symbol Parameter
T
A
Min. Typ. Max. Min. Max. Min. Max.
C
C
Input Capacitance
IN
Power Dissipation
PD
Capacitance
410 10 10pF
18 pF
(note 1)
1) CPD is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without
load. (R ef er to Test Circ ui t). Averag e operating current can be obtained by t he following equation. I
Figure 4: Test Circuit
-40 to 85°C -55 to 125°C
= CPD x VCC x fIN + I
CC(opr)
CC
Unit
CL =15/50pF or equivalent (i ncludes jig an d probe capac i tance)
= Z
R
of pulse generator (typically 50Ω)
T
OUT
Figure 5: Waveform - Propagation Delays For Inverting Outputs (f=1MHz; 50% duty cycle)
5/12
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74VHC238
Figure 6: Waveform 2: Propagation Delays For Non-inverting Outputs (f=1MHz; 50% duty cycle)
6/12
Page 7
SO-16 MECHANICAL DATA
74VHC238
DIM.
A 1.75 0.068
a1 0.1 0.25 0.004 0.010
a2 1.64 0.063
b 0.35 0.46 0.013 0.018
b1 0.19 0.25 0.007 0.010
C 0.5 0.019
c1 45° (typ.)
D 9.8 10 0.385 0.393
E 5.8 6.2 0.228 0.244
e 1.27 0.050
e3 8.89 0.350
F 3.8 4.0 0.149 0.157
G 4.6 5.3 0.181 0.208
L 0.5 1.27 0.019 0.050
M 0.62 0.024
S8° (max.)
MIN. TYP MAX. MIN. TYP. MAX.
mm. inch
0016020D
7/12
Page 8
74VHC238
TSSOP16 MECHANICAL DATA
mm. inch
DIM.
MIN. TYP MAX. MIN. TYP. MAX.
A 1.2 0.047
A1 0.05 0.15 0.002 0.004 0.006
A2 0.8 1 1.05 0.031 0.039 0.041
b 0.19 0.30 0.007 0.012
c 0.09 0.20 0.004 0.0079
D 4.9 5 5.1 0.193 0.197 0.201
E 6.2 6.4 6.6 0.244 0.252 0.260
E1 4.3 4.4 4.48 0.169 0.173 0.176
e 0.65 BSC 0.0256 BSC
K0˚ 8˚0˚ 8˚
L 0.45 0.60 0.75 0.018 0.024 0.030
A2
A
A1
b
e
c
K
L
E
D
E1
PIN 1 IDENTIFICATION
8/12
1
0080338D
Page 9
74VHC238
Tape & Reel SO-16 MECHANICAL DATA
mm. inch
DIM.
MIN. TYP MAX. MIN. TYP. MAX.
A 330 12.992
C 12.8 13.2 0.504 0.519
D 20.2 0.795
N 60 2.362
T 22.4 0.882
Ao 6.45 6.65 0.254 0.262
Bo 10.3 10.5 0.406 0.414
Ko 2.1 2.3 0.082 0.090
Po 3.9 4.1 0.153 0.161
P 7.9 8.1 0.311 0.319
9/12
Page 10
74VHC238
Tape & Reel TSSOP16 MECHANICAL DATA
mm. inch
DIM.
MIN. TYP MAX. MIN. TYP. MAX.
A 330 12.992
C 12.8 13.2 0.504 0.519
D 20.2 0.795
N 60 2.362
T 22.4 0.882
Ao 6.7 6.9 0.264 0.272
Bo 5.3 5.5 0.209 0.217
Ko 1.6 1.8 0.063 0.071
Po 3.9 4.1 0.153 0.161
P 7.9 8.1 0.311 0.319
10/12
Page 11
Table 9: Revision History
Date Revision Description of Change s
12-Nov-2004 4 Order Codes Revision - pag. 1.
74VHC238
11/12
Page 12
74VHC238
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of use of s uch inf ormati on nor for a ny infr ing eme nt o f p atent s or o ther ri ghts of third parties wh ich m ay res ult fr om it s us e. No li cens e i s gr an ted
by implication or otherwise under any patent or patent rights of STMicroelectronics. Speci fications mentioned in this publication are subject
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