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Teilenummer | DM74S251 |
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Beschreibung | TRI-STATE 1 of 8 Line Data Selector/Multiplexer | |
Hersteller | National Semiconductor | |
Logo | ||
Gesamt 6 Seiten www.DataSheet4U.com
June 1989
DM54S251 DM74S251 TRI-STATE 1 of 8 Line
Data Selector Multiplexer
General Description
These data selectors multiplexers contain full on-chip bina-
ry decoding to select one-of-eight data sources and feature
a strobe-controlled TRI-STATE output The strobe must be
at a low logic level to enable these devices The TRI-STATE
outputs permit direct connection to a common bus When
the strobe input is high both outputs are in a high-imped-
ance state in which both the upper and lower transistors of
each totem pole output are off and the output neither drives
nor loads the bus significantly When the strobe is low the
outputs are activated and operate as standard TTL totem-
pole outputs
To minimize the possibility that two outputs will attempt to
take a common bus to opposite logic levels the output con-
trol circuitry is designed so that the average output disable
time is shorter than the average output enable time
Features
Y TRI-STATE version of S151
Y Interface directly with system bus
Y Perform parallel-to-serial conversion
Y Permit multiplexing from N-lines to one line
Y Complementary outputs provide true and inverted data
Y Max no of common outputs
54S 39
74S 129
Y Typical propagation delay time (D to Y) 8 ns
Y Typical power dissipation 275 mW
Connection Diagram
Function Table
TL F 6480 – 1
Order Number DM54S251J or DM74S251N
See NS Package Number J16A or N16E
Inputs
Outputs
Select
C BA
Strobe
S
Y
W
X XX
L LL
L LH
L HL
L HH
H LL
H LH
H HL
H HH
H
L
L
L
L
L
L
L
L
ZZ
D0 D0
D1 D1
D2 D2
D3 D3
D4 D4
D5 D5
D6 D6
D7 D7
H e High Logic Level L e Low Logic Level
X e Don’t Care Z e High Impedance (Off)
D0 D1 D7 e The Level of the respective D input
TRI-STATE is a registered trademark of National Semiconductor Corporation
C1995 National Semiconductor Corporation TL F 6480
RRD-B30M105 Printed in U S A
Physical Dimensions inches (millimeters) (Continued)
16-Lead Molded Dual-In-Line Package (N)
Order Number DM74S251N
NS Package Number N16E
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION As used herein
1 Life support devices or systems are devices or
systems which (a) are intended for surgical implant
into the body or (b) support or sustain life and whose
failure to perform when properly used in accordance
with instructions for use provided in the labeling can
be reasonably expected to result in a significant injury
to the user
2 A critical component is any component of a life
support device or system whose failure to perform can
be reasonably expected to cause the failure of the life
support device or system or to affect its safety or
effectiveness
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National does not assume any responsibility for use of any circuitry described no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications
6 Page | ||
Seiten | Gesamt 6 Seiten | |
PDF Download | [ DM74S251 Schematic.PDF ] |
Teilenummer | Beschreibung | Hersteller |
DM74S251 | TRI-STATE 1 of 8 Line Data Selector/Multiplexer | National Semiconductor |
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