SGS Thomson Microelectronics 74VHCT238A Datasheet

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74VHCT238A

3 TO 8 LINEDECODER

■ HIGHSPEED:t

■ LOW POWER DISSIPATION:

=4 µA (MAX.)at TA=25oC

I

CC

■ COMPATIBLEWITHTTLOUTPUTS:

=2V(MIN),VIL=0.8V(MAX)

V

IH

■ POWERDOWNPROTECTIONON INPUTS&

=8ns (TYP.)atVCC=5V

PD

OUTPUTS

■ SYMMETRICALOUTPUTIMPEDANCE:

|I

|=IOL=8 mA(MIN)

OH

■ BALANCEDPROPAGATIONDELAYS:

t

≅ t

PLH

PHL

■ OPERATINGVOLTAGERANGE:

(OPR)= 4.5Vto 5.5V

V

CC

■ PINANDFUNCTIONCOMPATIBLEWITH

74SERIES238

■ IMPROVEDLATCH-UPIMMUNITY

DESCRIPTION

The 74VHCT238A is an advanced high-speed
CMOS 3 TO 8 LINE DECODER fabricated with
sub-micron silicon gate and double-layer metal
wiringC

2

MOStechnology.

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

SOP TSSOP

ORDER CODES

PACKAGE TUBE T & R

SOP 74VHCT238AM 74VHCT238AMTR

TSSOP 74VHCT238ATTR

G2A or G2B is held high, decoding function is
inhibitedand all the 8 outputsgo to low.

Three enable inputs are provided to ease
cascade connection and application of this
addressdecoders for memorysystems.

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
devicecan be usedto 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.

PIN CONNECTION AND IEC LOGICSYMBOLS

March 2000

1/8

74VHCT238A

INPUT EQUIVALENTCIRCUIT

PIN DESCRIPTION

PI N No SYM BO L NAM E AND FUNCT I O N

1, 2, 3 A, B, C Address Inputs

4, 5 G2A, G2B Enable Inputs

6 G1 Enable Input

15, 14, 13,
12, 11, 10,

9, 7

8 GND Ground (0V)

16 V

Y0 to Y7 Outputs

CC

Positive Supply Voltage

TRUTH TABLE

INPUTS OUTPUTS

ENABLE SELECT

G2BG2AG1 C B A Y0Y1Y2Y3Y4Y5Y6Y7

XXLXXXLLLLLLLL
XHXXXXLLLLLLLL
HXXXXXLLLLLLLL
LLHLLLHLLLLLLL
LLHLLHLHLLLLLL
LLHLHLLLHLLLLL
LLHLHHLLLHLLLL
LLHHLLLLLLHLLL
LLHHLHLLLLLHLL
LLHHHLLLLLLLHL
LLHHHHLLLLLLLH

X:Don’tCare

LOGICDIAGRAM

Thislogic diagram has notbeused to estimate propagation delays

2/8

74VHCT238A

ABSOLUTE MAXIMUM RATINGS

Symb o l Para met er Value U n i t

V

V
V
V

I

I

OK

I

or I

I

CC

T

T

AbsoluteMaximumRatingsarethosevaluesbeyondwhichdamageto thedevicemayoccur.Functionaloperationunderthesecondition isnotimplied.

1)V

=0

CC

2)HighorLowState

RECOMMENDED OPERATINGCONDITIONS

Symb o l Para met er Value Unit

V

V
V
V

T

dt/dv

1)VCC=0

2)HighorLowState
from0.8Vto 2V

3)V

IN

Supply Voltage -0.5 to +7.0 V

CC

DC Input Voltage -0.5 to +7.0 V

I

DC Output Voltage (see note 1) -0.5 to +7.0 V

O

DC Output Voltage (see note 2) -0.5 to VCC+ 0.5 V

O

DC Input Diode Current - 20 mA

IK

DC Output Diode Current
DC Output Current

O

DC VCCor Ground Current ±50 mA

GND

Storage Temperature -65 to +150

stg

Lead Temperature (10 sec) 300

L

Supply Voltage 4.5 to 5.5 V

CC

Input Voltage 0 to 5.5 V

I

Output Voltage (see note 1) 0 to 5.5 V

O

Output Voltage (see note 2) 0 to V

O

Operating Temperature -40 to +85

op

Input Rise and Fall Time (see note 3) (V

=5.0±0.5V)

CC

20 mA

±

25 mA

±

CC

0 to 20 ns/V

o

C

o

C

V

o

C

DC SPECIFICATIONS

Symb o l Para met er Test C o n dit io ns Val u e Uni t

T

=25oC -40 to 85oC

A

1.35 1.5 mA

µ

V

V

V

V

I

∆I

I

OPD

V

CC

High Level Input

IH

(V)

4.5 to 5.5 2 2 V

Min. Typ. Max. Min. Max.

Voltage
Low Level Input

IL

4.5 to 5.5 0.8 0.8 V

Voltage
High Level Output

OH

Voltage
Low Level Output

OL

Voltage
Input Leakage Current 0 to 5.5 VI= 5.5V or GND ±0.1 ±1.0 µA

I

I

Quiescent Supply

CC

4.5 IO=-50 µA 4.4 4.5 4.4

4.5 I

=-8 mA 3.94 3.8

O

4.5 IO=50 µ A 0.0 0.1 0.1

4.5 I

=8 mA 0.36 0.44

O

5.5 VI=VCCorGND 4 40

Current
Additional Worst Case

CC

Supply Current

5.5 One Input at 3.4V,
other input at V

CC

or

GND

Output Leakage

0V

= 5.5V 0.5 5.0 µA

OUT

Current

V

V

A

3/8