74ALS257N Ver la hoja de datos (PDF) - Philips Electronics
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Fabricante
74ALS257N Datasheet PDF : 11 Pages
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Philips Semiconductors
Data selector/multiplexer
Product specification
74ALS257/74ALS258
74ALS257 Quad 2-input data selector, non-inverting (3-State)
74ALS258 Quad 2-input data selector, inverting (3-State)
DESCRIPTION
The 74ALS257 is a quad 2-input multiplexer which selects 4 bits of
data from one of two sources under the control of a common select
input (S). The output enable input (OE) is active when Low. When
OE is High, all of the outputs (Yn) are forced to a High impedance
state (3-State) regardless of all other input conditions.
Moving data from two registers to a common output bus is a typical
use of the 74ALS257. The state of the select input determines the
particular register from which data comes.
The device is the logic implementation of 4-pole, 2-position switch
where the position of the switch is determined by the logic levels
supplied to the select input. The 74ALS258 is similar but has
inverting outputs (Yn).
TYPE
TYPICAL
PROPAGATION DELAY
74ALS257
74ALS258
7.0ns
7.0ns
TYPICAL
SUPPLY CURRENT
(TOTAL)
7mA
7mA
ORDERING INFORMATION
ORDER CODE
DESCRIPTION
16-pin plastic DIP
COMMERCIAL RANGE
VCC = 5V ±10%,
Tamb = 0°C to +70°C
74ALS257N, 74ALS258
16-pin plastic SO
74ALS257D, 74ALS258D
16-pin plastic SSOP
Type II
74ALS257DB, 74ALS258DB
DRAWING
NUMBER
SOT38-4
SOT109-1
SOT338-1
INPUT AND OUTPUT LOADING AND FAN-OUT TABLE
PINS
DESCRIPTION
74ALS (U.L.)
HIGH/LOW
Ina, Inb, Inc, Ind
Data inputs
1.0/1.0
S
Select input
1.0/1.0
OE
Enable input
1.0/1.0
Ya – Yd, Ya – Yd
Data outputs
20/240
NOTE: One (1.0) ALS unit load is defined as: 20µA in the High state and 0.1mA in the Low state.
LOAD VALUE
HIGH/LOW
20µA/0.1mA
20µA/0.1mA
20µA/0.1mA
0.4mA/24mA
PIN CONFIGURATION – 74ALS257
PIN CONFIGURATION – 74ALS258
S1
I0a 2
I1a 3
Ya 4
I0b 5
I1b 6
Yb 7
GND 8
16 VCC
15 OE
14 I0d
13 I1d
12 Yd
11 I0c
10 I1c
9 Yc
SF00673
S1
I0a 2
I1a 3
Ya 4
I0b 5
I1b 6
Yb 7
GND 8
16 VCC
15 OE
14 I0d
13 I1d
12 Yd
11 I0c
10 I1c
9 Yc
SC00079
1991 Feb 08
2
853–1130 01670
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