Philips N74ALS251D, N74ALS251N Datasheet

INTEGRATED CIRCUITS

74ALS251

8±input multiplexer (3±State)

Product specification	1991 Feb 08
IC05 Data Handbook

m n r

Philips Semiconductors	Product specification
8-input multiplexer (3-State)	74ALS251

FEATURES

•8-to-1 multiplexing

•On chip decoding

•Multifunction capability

•Inverting and non-inverting outputs

•Both outputs are 3-State for further multiplexer expansion

DESCRIPTION

The 74ALS251 is a logic implementation of a single 8-position switch with the switch position controlled by the state of three select (S0, S1, S2) inputs. True (Y) and complementary (Y) outputs are both provided.

The output enable (OE) is active Low. When OE is High, both outputs are in High impedance state, allowing multiple connections to a common bus without driving nor loading the bus significantly.

When the outputs of more than one device are tied together, the user must ensure that there is no overlap in the active-Low portion of the output enable voltages in order to avoid high currents that could exceed the maximum current rating.

		TYPICAL	TYPICAL
	TYPE		SUPPLY CURRENT
		PROPAGATION DELAY
			(TOTAL)
	74ALS251	7.0ns	7.5mA

PIN CONFIGURATION

	I3			1		16	VCC
	I2						I4
				2		15
	I1						I5
				3		14
	I0						I6
				4		13
		Y					I7
				5		12
							S0
		Y		6		11
							S1
	OE			7		10
GND							S2
				8		9

			SC00066
	ORDERING INFORMATION
		ORDER CODE
			DRAWING
	DESCRIPTION	COMMERCIAL RANGE
			NUMBER
		VCC = 5V ±10%,
		Tamb = 0°C to +70°C
	16-pin plastic DIP	74ALS251N	SOT38-4
	16-pin plastic SO	74ALS251D	SOT109-1

INPUT AND OUTPUT LOADING AND FAN-OUT TABLE

PINS																		DESCRIPTION								74ALS (U.L.)						LOAD VALUE
																										HIGH/LOW						HIGH/LOW
I0 ± I7										Data inputs															1.0/1.0							20μA/0.1mA
S0 ± S2										Select inputs															1.0/1.0							20μA/0.1mA
										Output Enable input (active-Low)															1.0/1.0							20μA/0.1mA
	OE
Y,										Data outputs															130/240							2.5mA/24mA
			Y
NOTE: One (1.0) ALS unit load is defined as: 20μA in the High state and 0.1mA in the Low state.
LOGIC SYMBOL																								IEC/IEEE SYMBOL
																										7
																											EN		MUX
						4		3		2		1		15		14		13		12						11
																											0
																								10					G	0		5
						I0		I1		I2		I3		I4		I5		I6		I7						9	2			7
11						S0																		4
10						S1																		3
9						S2																				2
7						OE						Y		Y												1						6
																										15
																								14
												5		6										13
VCC = Pin 16																								12
GND = Pin 8																						SC00067										SC00068

1991 Feb 08

2

853±1377 01670

Philips Semiconductors	Product specification
8-input multiplexer (3-State)	74ALS251

LOGIC DIAGRAM
	I0	I1	I2	I3	I4	I5	I6		I7
	4	3	2		1	15	14	13	12
S2	9
S1	10
S0	11
OE	7

		5	6
VCC = Pin 16	Y
			Y
GND = Pin 8					SC00069

FUNCTION TABLE

INPUTS

OUTPUTS

S2

S1

S0

Y

OE

Y

X

X

X

H

Z

Z

L

L

L

L

I0

I0

L

L

H

L

I1

I1

L

H

L

L

I2

I2

L

H

H

L

I3

I3

H

L

L

L

I4

I4

H

L

H

L

I5

I5

H

H

L

L

I6

I6

H

H

H

L

I7

I7

H

=

High voltage level

L

=

Low voltage level

X

=

Don't care

Z

=

High impedance ªoffº state

ABSOLUTE MAXIMUM RATINGS

(Operation beyond the limit set forth in this table may impair the useful life of the device. Unless otherwise noted these limits are over the operating free air temperature range.)

SYMBOL	PARAMETER	RATING	UNIT
VCC	Supply voltage	±0.5 to +7.0	V
VIN	Input voltage	±0.5 to +7.0	V
IIN	Input current	±30 to +5	mA
VOUT	Voltage applied to output in High output state	±0.5 to VCC	V
IOUT	Current applied to output in Low output state	48	mA
Tamb	Operating free-air temperature range	0 to +70	°C
Tstg	Storage temperature range	±65 to +150	°C

RECOMMENDED OPERATING CONDITIONS

	SYMBOL	PARAMETER		LIMITS		UNIT
			MIN	NOM	MAX
	VCC	Supply voltage	4.5	5.0	5.5	V
	VIH	High-level input voltage	2.0			V
	VIL	Low-level input voltage			0.8	V
	IIK	Input clamp current			±18	mA
	IOH	High-level output current			±2.6	mA
	IOL	Low-level output current			24	mA
	Tamb	Operating free-air temperature range	0		+70	°C

1991 Feb 08

3