datasheetbank_Logo
Integrated circuits, Transistor, Semiconductors Search and Datasheet PDF Download Site

54LS257 View Datasheet(PDF) - Motorola => Freescale

Part Name
Description
View to exact match
54LS257
Motorola
Motorola => Freescale Motorola
54LS257 Datasheet PDF : 6 Pages
1 2 3 4 5 6
SN54/74LS257B D SN54/74LS258B
FUNCTIONAL DESCRIPTION
The LS257B and LS258B are Quad 2-Input Multiplexers
with 3-state outputs. They select four bits of data from two
sources each under control of a Common Data Select Input.
When the Select Input is LOW, the I0 inputs are selected and
when Select is HIGH, the I1 inputs are selected. The data on
the selected inputs appears at the outputs in true (non-
inverted) form for the LS257B and in the inverted form for the
LS258B.
The LS257B and LS258B are the logic implementation of a
4-pole, 2-position switch where the position of the switch is
determined by the logic levels supplied to the Select Input. The
logic equations for the outputs are shown below:
LS257B
Za = E0 (I1a S + I0a S) Zb = E0 (I1b S + I0b S)
Zc = E0 (I1c S + I0c S) Zd = E0 (I1d S + I0d S)
When the Output Enable Input (E0) is HIGH, the outputs are
forced to a high impedance “off” state. If the outputs are tied
together, all but one device must be in the high impedance
state to avoid high currents that would exceed the maximum
ratings. Designers should ensure that Output Enable signals
to 3-state devices whose outputs are tied together are
designed so there is no overlap.
LS258B
Za = E0 (I1a S + I0a S) Zb = E0 (I1b S + I0b S)
Zc = E0 (I1c S + I0c S) Zd = E0 (I1d S + I0d S)
TRUTH TABLE
OUTPUT SELECT
ENABLE INPUT
EO
S
H
X
L
H
L
H
L
L
L
L
H = HIGH Voltage Level
L = LOW Voltage Level
X = Don’t Care
(Z) = High Impedance (off)
DATA OUTPUTS OUTPUTS
INPUTS LS257B LS258B
I0 I1
Z
Z
XX
(Z)
(Z)
XL
L
H
XH
H
L
LX
L
H
HX
H
L
GUARANTEED OPERATING RANGES
Symbol
Parameter
VCC
Supply Voltage
TA
Operating Ambient Temperature Range
IOH
Output Current — High
IOL
Output Current — Low
Min
Typ
Max
Unit
54
4.5
5.0
5.5
V
74
4.75
5.0
5.25
54
– 55
25
125
°C
74
0
25
70
54
– 1.0
mA
74
– 2.6
54
12
mA
74
24
FAST AND LS TTL DATA
5-429
 

Share Link: 

datasheetbank.com [ Privacy Policy ] [ Request Datasheet ] [ Contact Us ]