Fairchild Semiconductor 74AC251SJX, 74AC251SJ, 74AC251SCX, 74AC251SC, 74AC251PC Datasheet

© 1999 Fairchild Semiconductor Corporation DS009945 www.fairchildsemi.com

November 1988
Revised November 1999

74AC251 • 74ACT251 8-Input Multiplexer with 3-STATE Output

74AC251 • 74ACT251
8-Input Multiplexer with 3-STATE Output

General Description

The AC/ACT251 is a high -speed 8-input digital mu l tipl ex er.
It provides, in one package, the ability to select on e bit of
data from up to eight sources. It can be used as universal
function generator t o generate any logic function of fo ur
variables. Both true and co mplementary outputs are pro­vided.

Features

■ ICC reduced by 50%

■ Multifunctional capability

■ On-chip select logic decoding

■ Inverting and noninverting 3-STATE outputs

■ Outputs source/sink 24 mA

■ ACT251 has TTL-compatible inputs

Ordering Code:

Device also available in Tape and Reel. Specify by appending su ffix le tter “X” to the ordering code.

Logic Symbols

IEEE/IEC

Connection Diagram

Pin Descriptions

FACT is a trademark of Fairchild Semiconductor Corporation.

Order Number Package Number Package Description

74AC251SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
74AC251SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
74AC251MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74AC251PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
74ACT251SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
74ACT251MTC MTC16 16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide
74ACT251PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide

Pin Names Description

S

0–S2

Select Inputs

OE

3-STATE Output Enable Input

I

0–I7

Multiplexer Inputs
Z 3-STATE Multiplexer Output
Z

Complementary 3-STATE Multiplexer Output

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74AC251 • 74ACT251

Functional Description

This device is a l ogical i mplementa tion of a sin gle-pol e, 8­position switch with the switch position controlled by the
state of three Select i npu ts, S

0

, S1, S2. Both true and com-

plementary outputs ar e provided. The Output Enab le input
(OE

) is active LOW. When it is activated, the logic functio n

provided at the output is:
Z = OE

• (I0 • S0 • S1 • S2 + I1• S0 • S1 • S2 +

I

2

• S0 • S1 • S2 + I3 • S0 • S1 • S2 +

I

4

• S0 • S1 • S2 + I5 • S0 • S1 • S2 +

I

6

• S0 • S1 • S2 + I7 • S0 • S1 • S2)

When the Output Ena ble is HIGH, both outpu ts are in the
high impedance (High Z) state. This feature allows multi­plexer expansion by tyi ng the outpu ts of up to 128 dev ices
together. When the outputs of the 3-STATE devices are
tied together, all but one device must b e i n th e h igh im ped ­ance state to avoi d high currents that would exceed the
maximum ratings. The Output Enable signals should be
designed to ensure there is no overlap in the active-LOW
portion of the enable voltages.

Tr uth Table

H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Z = High Impedance

Logic Diagram

Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.

Inputs Outputs

OE S

2

S

1

S

0

Z Z

H X X X Z Z
L L L LI

0

I

0

L L L HI1 I

1

L L H LI2 I

2

L L H HI3 I

3

L H L LI4 I

4

L H L HI5 I

5

L H H LI6 I

6

L H H HI7 I

7

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74AC251 • 74ACT251

Absolute Maximum Ratings(Note 1) Recommended Operating

Conditions

Note 1: Absolute max imum ratings are those values beyond w hich damage

to the device may occu r. The databook spe cificatio ns shou ld be met, wit h­out exception, to ensure that the system de sign is relia ble over its p ower
supply, temperature, and output/input loading variables. Fairchild does not
recommend operation of FACT circuits outside databook specif ic at ions.

DC Electrical Characteristics for AC

Note 2: All outputs loaded; thres holds on input associate d w it h output under test.
Note 3: Maximum test duration 2.0 ms, one output loaded at a time.
Note 4: I

IN

and ICC @ 3.0V are guaranteed to be less than or equa l t o th e respective limit @ 5.5V VCC.

Supply Voltage (VCC) −0.5V to +7.0V
DC Input Diode Current (I

IK

)

V

I

= −0.5V −20 mA

V

I

= VCC + 0.5V +20 mA

DC Input Voltage (V

I

) −0.5V to VCC + 0.5V

DC Output Diode Current (I

OK

)

V

O

= −0.5V −20 mA

V

O

= VCC + 0.5V +20 mA

DC Output Voltage (V

O

) −0.5V to VCC + 0.5V

DC Output Source

or Sink Current (I

O

) ±50 mA

DC V

CC

or Ground Current

per Output Pin (I

CC

or I

GND

) ±50 mA

Storage Temperature (T

STG

) −65°C to +150°C

Junction Temperature (T

J

)

PDIP 140°C

Supply Voltage (V

CC

)
AC 2.0V to 6.0V
ACT 4.5V to 5.5V

Input Voltage (V

I

) 0V to V

CC

Output Voltage (VO) 0V to V

CC

Operating Temperature (TA) −40°C to +85°C
Minimum Input Edge Rate (∆V/∆t)

AC Devices
V

IN

from 30% to 70% of V

CC

VCC @ 3.3V, 4.5V, 5.5V 125 mV/ns

Minimum Input Edge Rate (∆V/∆t)

ACT Devices
V

IN

from 0.8V to 2.0V

V

CC

@ 4.5V, 5.5V 125 mV/ns

Symbol Parameter

V

CC

(V)

T

A

= +25°C TA = −40°C to +85°C

Units Conditions

Typ Guaranteed Limits

V

IH

Minimum HIGH Level 3.0 1.5 2.1 2.1 V

OUT

= 0.1V

Input Voltage 4.5 2.25 3.15 3.15 V or VCC − 0.1V

5.5 2.75 3.85 3.85

V

IL

Maximum LOW Level 3.0 1.5 0.9 0.9 V

OUT

= 0.1V

Input Voltage 4.5 2.25 1.35 1.35 V or VCC − 0.1V

5.5 2.75 1.65 1.65

V

OH

Minimum HIGH Level 3.0 2.99 2.9 2.9
Output Voltage 4.5 4.49 4.4 4.4 V I

OUT

= −50 µA

5.5 5.49 5.4 5.4
VIN = VIL or V

IH

3.0 2.56 2.46 IOH = −12 mA

4.5 3.86 3.76 V I

OH

= −24 mA

5.5 4.86 4.76 I

OH

= −24 mA (Note 2)

V

OL

Maximum LOW Level 3.0 0.002 0.1 0.1
Output Voltage 4.5 0.001 0.1 0.1 V I

OUT

= 50 µA

5.5 0.001 0.1 0.1
VIN = VIL or V

IH

3.0 0.36 0.44 IOL = 12 mA

4.5 0.36 0.44 V IOL = 24 mA

5.5 0.36 0.44 IOL = 24 mA (Note 2)

IIN (Note 4) Maximum Input Leakage Current 5.5 ±0.1 ±1.0 µAVI = VCC, GND
I

OZ

Maximum 3-STATE VI (OE) = VIL, V

IH

Current 5.5 ±0.25 ±2.5 µAVI = VCC, V

GND

VO = VCC, GND

I

OLD

Minimum Dynamic 5.5 75 mA V

OLD

= 1.65V Max

I

OHD

Output Current (Note 3) 5.5 −75 mA V

OHD

= 3.85V Min

I

CC

(Note 4) Maximum Quiescent Supply Curent 5.5 4.0 40.0 µAVIN = VCC or GND