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DM74LS251N

Part # DM74LS251N
Description Encoders, Decoders, Multiplexers & Demultiplexers 3-STATE
Category IC
Availability In Stock
Qty 7
Qty Price
1 + $0.42771
Manufacturer Available Qty
National Semiconductor Corp
Date Code: 7428
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Technical Document


DISCLAIMER: The information provided herein is solely for informational purposes. Customers must be aware of the suitability of this product for their application, and consider that variable factors such as Manufacturer, Product Category, Date Codes, Pictures and Descriptions may differ from available inventory.

© 2000 Fairchild Semiconductor Corporation DS006415 www.fairchildsemi.com
August 1986
Revised March 2000
DM74LS251 3-STATE 1-of-8 Line Data Selector/Multiplexer
DM74LS251
3-STATE 1-of-8 Line Data Selector/Multiplexer
General Description
These data selectors/multiplexers contain full on-chip
binary decoding to select one-of-eight data sources, and
feature a strobe-controlled 3-STATE output. The strobe
must be at a low logic level to enable these devices. The 3-
STATE outputs permit direct connection to a common bus.
When the strobe input is HIGH, both outputs are in a high-
impedance state in which both the upper and lower transis-
tors of each totem-pole output are OFF, and the output nei-
ther 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
3-STATE version of DM74LS151
Interface directly with system bus
Perform parallel-to-serial conversion
Permit multiplexing from N-lines to one line
Complementary outputs provide true and inverted data
Maximum number of common outputs: 129
Typical propagation delay time (D to Y): 17 ns
Typical power dissipation: 35 mW
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram Function Table
H = HIGH Logic Level
L = LOW Logic Level
X = Don't Care
Z = High Impedance (OFF)
D0, D1…D7 = The level of the respective D input
Order Number Package Number Package Description
DM74LS251M M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS251N N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Inputs Outputs
Select Strobe
YW
CBA S
XXX H Z Z
LLL L D0D0
LLH L D1D1
LHL L D2D2
LHH L D3D3
HLL L D4D4
HLH L D5D5
HHL L D6D6
HHH L D7D7
www.fairchildsemi.com 2
DM74LS251
Logic Diagram
3 www.fairchildsemi.com
DM74LS251
Absolute Maximum Ratings(Note 1)
Note 1: The “Absolute Maximum Ratings” are those values beyond which
the safety of the device cannot be guaranteed. The device should not be
operated at these limits. The parametric values defined in the “Electrical
Characteristics” table are not guaranteed at the absolute maximum ratings.
The “Recommended Operating Conditions” table will define the conditions
for actual device operation.
Recommended Operating Conditions
Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Note 2: All typicals are at V
CC
= 5V, T
A
= 25°C.
Note 3: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 4: I
CC1
is measured with the outputs open, STROBE grounded, and all other inputs at 4.5V.
Note 5: I
CC2
is measured with the outputs open and all inputs at 4.5V.
Supply Voltage 7V
Input Voltage 7V
Operating Free Air Temperature Range 0°C to +70°C
Storage Temperature Range 65°C to +150°C
Symbol Parameter Min Nom Max Units
V
CC
Supply Voltage 4.75 5 5.25 V
V
IH
HIGH Level Input Voltage 2 V
V
IL
LOW Level Input Voltage 0.8 V
I
OH
HIGH Level Output Current 2.6 mA
I
OL
LOW Level Output Current 24 mA
T
A
Free Air Operating Temperature 0 70 °C
Symbol Parameter Conditions Min
Typ
Max Units
(Note 2)
V
I
Input Clamp Voltage V
CC
= Min, I
I
= 18 mA 1.5 V
V
OH
HIGH Level V
CC
= Min, I
OH
= Max
2.4 3.1 V
Output Voltage V
IL
= Max, V
IH
= Min
V
OL
LOW Level V
CC
= Min, I
OL
= Max
0.35 0.5
Output Voltage V
IL
= Max, V
IH
= Min V
I
OL
= 12 mA, V
CC
= Min 0.25 0.4
I
I
Input Current @ Max Input Voltage V
CC
= Max, V
I
= 7V 0.1 mA
I
IH
HIGH Level Input Current V
CC
= Max, V
I
= 2.7V 20 µA
I
IL
LOW Level Input Current V
CC
= Max, V
I
= 0.4V 0.4 mA
I
OZH
Off-State Output Current with V
CC
= Max, V
O
= 2.7V
20 µA
HIGH Level Output Voltage Applied V
IH
= Min, V
IL
= Max
I
OZL
Off-State Output Current with V
CC
= Max, V
O
= 0.4V
20 µA
LOW Level Output Voltage Applied V
IH
= Min, V
IL
= Max
I
OS
Short Circuit Output Current V
CC
= Max (Note 3) 20 100 mA
I
CC1
Supply Current V
CC
= Max (Note 4) 6.1 10 mA
I
CC2
Supply Current V
CC
= Max (Note 5) 7.1 12 mA
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