Datasheet 74AC257 Datasheet (SGS Thomson Microelectronics)

74AC257

QUAD 2 CHANNEL MULTIPLEXER (3-STATE)

■ HIGH SPEED: t

■ LOW POWE RDISSIPATION:

=8 µA (MAX.)atTA=25oC

I

CC

■ HIGHNOISEIMMUNITY:

V

NIH=VNIL

■ 50Ω TRANSMISSION LINE DRIVING

=28%VCC(MIN.)

=4.5ns (TYP.) at VCC=5V

PD

CAPABILITY

■ SYMMETRICALOUTPUT IMPEDANCE:

|I

|=IOL=24mA(MIN)

OH

■ BALANCEDPROPAGAT IONDELAYS:

t

≅ t

PLH

PHL

■ OPERATINGVOLTAGERAN GE:

V

(OPR )= 2V to 6V

CC

■ PIN AND FUNCTION COMPATIBLE WITH

74 SERIES257

■ IMPROVEDLATCH-UP IMMUNITY

DESCRIPTION

The AC257 is an advanced high-speed CMOS
QUAD 2 CHANNEL MULTIPLEXER (3-STATE)
fabricated with sub-micron silicon gate and
double-layermetalwiring C

2

MOS technology.

It is ideal for low power applications mantaining
high speed operation similar to equivalent Bipolar
SchottkyTTL.

B

(Plastic Package)

(Micro Package)

M

ORDERCODES:

74AC257B

These IC’s are composed of an independent 2
channel multiplexer with common SELECT and
ENABLEINPUT.

TheAC257 is a noninverting multiplexer.
Whenthe ENABLE INPUT is held ”High”, outputs

of both IC’s become high impedance state. If
SELECT INPUT is held ”Low”, ”A” data is
selected, when SELECT INPUT is ”High”, ”B”
datais chosen.

All inputs and outputs are equipped with
protectioncircuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.

PINCONNECTION AND IEC LOGIC SYMBOLS

April 1997

1/10

74AC257

INPUTAND OUTPUTEQUIVALENTCIRCUIT

TRUTH TABLE

INPUTS OUTPUTS

OESELECTABY

HXXXZ

LLLXL
LLHXH
LHXLL
LHXHH

X = DON’TCARE Z = HIGHIMPEDANCE

PIN DESCRIPTION

PI N No SYM B O L NAME A ND FUNCTI ON

1 SELECT Common Data Select Input
2, 5, 14, 11 1A to 4A Data Input From Source A
3, 6, 13, 10 1B to 4B Data Inputs from Source B

4, 7, 12, 9 1Y to 4Y 3 State Multiplexer Outputs

15 OE 3 State Output Enable

Inputs (Active LOW)

8 GND Ground (0V)

16 V

CC

Positive Supply Voltage

LOGICDIAGRAM

This logic diagram has not be used to estimate propagation delays

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74AC257

ABSOLUTE MAXIMUMRATINGS

Symb o l Parame t er Val u e Uni t

V

V

V

I

I

OK

I

orI

I

CC

T

T

Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied.

RECOMMENDEDOPERATINGCONDITIONS

Symb o l Parame t er Value Un i t

V

V

V

T

dt/dv Input Rise and Fall Time V

1) VINfrom 30%to70%of V

Supply Voltage -0.5 to +7 V

CC

DC Input Voltage -0.5 to VCC+ 0.5 V

I

DC Output Voltage -0.5 to VCC+ 0.5 V

O

DC Input Diode Current ± 20 mA

IK

DC Output Diode Current ± 20 mA
DC Output Current ± 50 mA

O

DC VCCor Ground Current ± 200 mA

GND

Storage Temperature -65 to +150

stg

Lead Temperature (10 sec) 300

L

Supply Voltage 2 to 6 V

CC

Input Voltage 0 to V

I

Output Voltage 0 to V

O

Operating Temperature: -40 to +85

op

= 3.0, 4.5 or 5.5 V(note 1) 8 ns/V

CC

CC

CC
CC

o

C

o

C

V
V

o

C

3/10

74AC257

DC SPECIFICATIONS

Symbol Parameter Test Condition s Value Unit

V

CC

(V)

High Level Input Voltage 3.0 VO= 0.1 V or

V

IH

4.5 3.15 2.25 3.15

V

CC

- 0.1 V

T

=25oC-40to85

A

Min. Typ. Ma x. Min. Max.

2.1 1.5 2.1

o

C

5.5 3.85 2.75 3.85

Low Level Input Voltage 3.0 VO= 0.1 V or

V

IL

4.5 2.25 1.35 1.35

V

CC

- 0.1 V

1.5 0.9 0.9

5.5 2.75 1.65 1.65

High Level Output

V

OH

Voltage

Low Level Output

V

OL

Voltage

Input Leakage Current

I

I

3 State Output Leakage

I

OZ

Current
Quiescent Supply

I

CC

3.0

4.5 I

5.5 I

V
V

3.0 I

4.5 I

5.5 I

3.0

4.5 I

5.5 I

V
V

3.0 I

4.5 I

5.5 I

5.5

5.5 VI=VIHor V

IO=-50 µA 2.9 2.99 2.9

(*)

I
IH

V

IL

=-50 µA 4.4 4.49 4.4

O

=

=-50 µA 5.4 5.49 5.4

or

O

=-12 mA 2.56 2.46

O

=-24 mA 3.86 3.76

O

=-24 mA 4.86 4.76

O

IO=50 µA 0.002 0.1 0.1

(*)

I
IH

V

IL

=50 µA 0.001 0.1 0.1

O

=

=50 µA 0.001 0.1 0.1

or

O

=12 mA 0.36 0.44

O

=24 mA 0.36 0.44

O

=24 mA 0.36 0.44

O

VI=VCCor GND ±0.1 ±1 µA

IL

±0.5 ±5 µA

VO=VCCor GND

5.5 VI=VCCor GND 8 80 µA

Current
Dynamic Output Current

I

OLD

(note 1, 2)

I

OHD

1) Maximum test duration 2ms, one output loaded at time

2) Incident wave switching is guaranteed on transmission lines with impedances as low as 50 Ω.
(*)All outputs loaded.

5.5 V

= 1.65 V max 75 mA

OLD

V

= 3.85 V min -75 mA

OHD

V

V

V

V

4/10

AC ELECTRICAL CHARACTERISTICS (CL= 50 pF, RL=500 Ω, Input tr=tf=3ns)

74AC257

Symbol Parameter Test Cond ition Value Unit

o

C

ns

ns

ns

ns

t

Propagation Delay Time

PLH

t

A,B to Y

PHL

Propagation Delay Time

t

PLH

t

SEL to Y

PHL

Output Enable Time 3.3

t

PZL

t

PZH

Output Disable Time 3.3

t

PLZ

t

PHZ

(*) Voltagerange is3.3V ± 0.3V
(**) Voltagerange is5V± 0.5V

V

3.3

5.0

3.3

5.0

5.0

5.0

(V)

CC

(**)

(**)

(**)

(**)

T

=25oC-40to85

A

Min. Typ. Ma x. Min. Max.

(*)

1.5 5.5 8.5 1.5 9

1.5 4.5 6 1.5 7

(*)

1.5 7 10.5 1.5 11.5

1.5 5.5 7.5 1.5 8.5

(*)

1.5 5.5 9 1.5 10

1.5 4.5 7.5 1.5 8.5

(*)

1.5 7 10 1.5 11

1.5 5.5 9 1.5 10

CAPACITIVE CHARACTERISTICS

Symbol Parameter Test Condition s Value Unit

=25oC-40to85

V

CC

(V)

C

Output Capacitance 5.0 8 pF

OUT

Input Capacitance 5.0 4 pF

C

IN

Power Dissipation

C

PD

5.0 20 pF

T

A

Min. Typ. Ma x. Min. Max.

Capacitance (note 1)

1) CPDis 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

(opr) =CPD• VCC•fIN+ICC/n (percircuit)

CC

o

C

TEST CIRCUIT

TEST SWITC H

t

PLH,tPHL

t

PZL,tPLZ

t

PZH,tPHZ

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

= 500Ω or equivalent

L=R1

R

of pulse generator (typically 50Ω)

T=ZOUT

Open

2V

CC

Open

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74AC257

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

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

cycle)

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WAVEFORM 3: OUTPUTENABLE AND DISABLE TIME (f=1MHz;50%duty cycle)

74AC257

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74AC257

Plastic DIP16 (0.25) MECHANICAL DATA

DIM.

MIN. TYP. MAX. MIN. TYP. MAX.

a1 0.51 0.020

B 0.77 1.65 0.030 0.065
b 0.5 0.020

b1 0.25 0.010

D 20 0.787
E 8.5 0.335
e 2.54 0.100

e3 17.78 0.700

F 7.1 0.280

I 5.1 0.201
L 3.3 0.130
Z 1.27 0.050

mm inch

8/10

P001C

SO16 MECHANICAL DATA

74AC257

DIM.

MIN. TYP. MAX. MIN. TYP. MAX.

A 1.75 0.068

a1 0.1 0.2 0.004 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.)

mm inch

P013H

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74AC257

Information furnished is believed to be accurate and reliable. However,SGS-THOMSON Microelectronicsassumesno responsability for the
consequencesof use ofsuch informationnorfor any infringement of patents or otherrights of third parties which may resultsfrom its use. No
licenseisgrantedby implicationor otherwise underany patentor patent rights ofSGS-THOMSON Microelectronics. Specificationsmentioned
in this publicationare subjectto change without notice.Thispublicationsupersedes and replacesall information previouslysupplied.
SGS-THOMSONMicroelectronics products are notauthorizedforuseas criticalcomponents in lifesupportdevicesor systemswithoutexpress
writtenapproval of SGS-THOMSONMicroelectonics.

 1997 SGS-THOMSONMicroelectronics- Printedin Italy - All Rights Reserved

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