74VHC238

3 TO 8 LINE DECODER

■ HIGH SPEED: tPD = 5.5 ns (TYP.) at VCC = 5V

■ LOW POWER DISSIPATION:
ICC = 4 µA (MAX.) at TA=25°C
■ HIGH NOISE IMMUNITY:
VNIH = V NIL = 28% VCC (MIN.)
■ POWER DOWN PROTECTION ON INPUTS
■ SYMMETRICAL OUTPUT IMPEDANCE: SOP TSSOP
|IOH| = IOL = 8 mA (MIN)
■ BALANCED PROPAGATION DELAYS:
tPLH ≅ tPHL ORDER CODES
■ OPERATING VOLTAGE RANGE: PACKAGE TUBE T&R
VCC(OPR) = 2V to 5.5V
SOP 74VHC238M 74VHC238MTR
■ PIN AND FUNCTION COMPATIBLE WITH
TSSOP 74VHC238TTR
74 SERIES 238
■ IMPROVED LATCH-UP IMMUNITY
Tree enable inputs are provided to ease cascade
DESCRIPTION connection and application of address decoders
The 74VHC238 is an advanced high-speed for memory systems.
CMOS 3 TO 8 LINE DECODER fabricated with Power down protection is provided on all inputs
sub-micron silicon gate and double-layer metal and 0 to 7V can be accepted on inputs with no
wiring C2MOS technology. regard to the supply voltage. This device can be
If the device is enabled, 3 binary select inputs (A, used to interface 5V to 3V.
B, and C) determine which one of the outputs will All inputs and outputs are equipped with
go high. If enable input G1 is held low or either protection circuits against static discharge, giving
G2A or G2B is held high, decoding function is them 2KV ESD immunity and transient excess
inhibited and all the 8 outputs go to low. voltage.

PIN CONNECTION AND IEC LOGIC SYMBOLS

June 2001 1/9

74VHC238

INPUT EQUIVALENT CIRCUIT PIN DESCRIPTION

PIN No SYMBOL NAME AND FUNCTION

1, 2, 3 A, B, C Address Inputs
4, 5 G2A, G2B Enable Inputs
6 G1 Enable Input
15, 14, 13, Y0 to Y7 Outputs
12, 11, 10, 9,
7
8 GND Ground (0V)
16 VCC Positive Supply Voltage

TRUTH TABLE

INPUTS
OUTPUTS
ENABLE SELECT

G2B G2A G1 C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
X X L X X X L L L L L L L L
X H X X X X L L L L L L L L
H X X X X X L L L L L L L L
L L H L L L H L L L L L L L
L L H L L H L H L L L L L L
L L H L H L L L H L L L L L
L L H L H H L L L H L L L L
L L H H L L L L L L H L L L
L L H H L H L L L L L H L L
L L H H H L L L L L L L H L
L L H H H H L L L L L L L H
X : Don’t care

LOGIC DIAGRAM

This logic diagram has not be used to estimate propagation delays

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 74VHC238

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

VCC Supply Voltage -0.5 to +7.0 V
VI DC Input Voltage -0.5 to +7.0 V
VO DC Output Voltage -0.5 to VCC + 0.5 V
IIK DC Input Diode Current - 20 mA
IOK DC Output Diode Current ± 20 mA
IO DC Output Current ± 25 mA
ICC or IGND DC VCC or Ground Current ± 75 mA
Tstg Storage Temperature -65 to +150 °C
TL Lead Temperature (10 sec) 300 °C
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is
not implied

RECOMMENDED OPERATING CONDITIONS

Symbol Parameter Value Unit

VCC Supply Voltage 2 to 5.5 V
VI Input Voltage 0 to 5.5 V
VO Output Voltage 0 to VCC V
Top Operating Temperature -55 to 125 °C
Input Rise and Fall Time (note 1) (VCC = 3.3 ± 0.3V) 0 to 100
dt/dv ns/V
(VCC = 5.0 ± 0.5V) 0 to 20
1) VIN from 30% to 70% of V CC

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74VHC238

DC SPECIFICATIONS

Test Condition Value

Symbol Parameter TA = 25°C -40 to 85°C -55 to 125°C Unit

VCC
(V)
Min. Typ. Max. Min. Max. Min. Max.
VIH High Level Input 2.0 1.5 1.5 1.5
Voltage 3.0 to V
0.7VCC 0.7VCC 0.7VCC
5.5
VIL Low Level Input 2.0 0.5 0.5 0.5
Voltage 3.0 to V
0.3VCC 0.3VCC 0.3VCC
5.5
VOH High Level Output 2.0 IO=-50 µA 1.9 2.0 1.9 1.9
Voltage IO=-50 µA
3.0 2.9 3.0 2.9 2.9
4.5 IO=-50 µA 4.4 4.5 4.4 4.4 V
3.0 IO=-4 mA 2.58 2.48 2.4
4.5 IO=-8 mA 3.94 3.8 3.7
VOL Low Level Output 2.0 IO=50 µA 0.0 0.1 0.1 0.1
Voltage IO=50 µA
3.0 0.0 0.1 0.1 0.1
4.5 IO=50 µA 0.0 0.1 0.1 0.1 V
3.0 IO=4 mA 0.36 0.44 0.55
4.5 IO=8 mA 0.36 0.44 0.55
II Input Leakage 0 to VI = 5.5V or GND ± 0.1 ±1 ±1 µA
Current 5.5
ICC Quiescent Supply
5.5 VI = VCC or GND 4 40 40 µA
Current

AC ELECTRICAL CHARACTERISTICS (Input tr = tf = 3ns)

Test Condition Value

Symbol Parameter TA = 25°C -40 to 85°C -55 to 125°C Unit

VCC CL
(V) (pF) Min. Typ. Max. Min. Max. Min. Max.
tPLH Propagation Delay 3.3 (*) 15 8.0 12.3 1.0 14.5 1.0 14.5
tPHL Time
A, B, C, to Y 3.3(*) 50 10.5 15.8 1.0 18.0 1.0 18.0
ns
5.0(**) 15 5.5 8.1 1.0 9.5 1.0 9.5
5.0(**) 50 7.0 10.1 1.0 11.5 1.0 11.5
tPLH Propagation Delay 3.3 (*) 15 8.1 12.8 1.0 15.0 1.0 15.0
tPHL Time (*)
G1 to Y 3.3 50 10.6 16.3 1.0 18.5 1.0 18.5
ns
5.0(**) 15 5.4 8.1 1.0 9.5 1.0 9.5
5.0(**) 50 6.9 10.1 1.0 11.5 1.0 11.5
tPLH Propagation Delay 3.3 (*) 15 8.1 12.3 1.0 14.5 1.0 14.5
tPHL Time
G2A, G2B to Y 3.3(*) 50 10.6 15.8 1.0 18.0 1.0 18.0
ns
(**) 15 5.7 8.1 1.0 9.5 1.0 9.5
5.0
5.0(**) 50 7.2 10.1 1.0 11.5 1.0 11.5
(*) Voltage range is 3.3V ± 0.3V
(**) Voltage range is 5.0V ± 0.5V

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 74VHC238

CAPACITIVE CHARACTERISTICS

Test Condition Value

Symbol Parameter TA = 25°C -40 to 85°C -55 to 125°C Unit

Min. Typ. Max. Min. Max. Min. Max.

CIN Input Capacitance 4 10 10 10 pF
CPD Power Dissipation
Capacitance 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. (Refer to Test Circuit). Average operating current can be obtained by the following equation. ICC(opr) = CPD x VCC x fIN + ICC

TEST CIRCUIT

CL =15/50pF or equivalent (includes jig and probe capacitance)

RT = ZOUT of pulse generator (typically 50Ω)

WAVEFORM 1: PROPAGATION DELAYS FOR INVERTING OUTPUTS (f=1MHz; 50% duty cycle)

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74VHC238

WAVEFORM 2: PROPAGATION DELAYS FOR NON-INVERTING OUTPUTS (f=1MHz; 50% duty cycle)

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 74VHC238

SO-16 MECHANICAL DATA

mm. inch
DIM.
MIN. TYP MAX. MIN. TYP. MAX.
A 1.75 0.068
a1 0.1 0.2 0.003 0.007
a2 1.65 0.064
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
S 8° (max.)

PO13H

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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 0.0089

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

K 0° 8° 0° 8°

L 0.45 0.60 0.75 0.018 0.024 0.030

A A2
K L
A1 b e
c E

E1

PIN 1 IDENTIFICATION
1
0080338D

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 74VHC238

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