DM74LS251 Datasheet by ON Semiconductor

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© 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
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DM74LS251
Logic Diagram
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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 VCC = 5V, TA = 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: ICC1 is measured with the outputs open, STROBE grounded, and all other inputs at 4.5V.
Note 5: ICC2 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
VCC Supply Voltage 4.75 5 5.25 V
VIH HIGH Level Input Voltage 2 V
VIL LOW Level Input Voltage 0.8 V
IOH HIGH Level Output Current 2.6 mA
IOL LOW Level Output Current 24 mA
TAFree Air Operating Temperature 0 70 °C
Symbol Parameter Conditions Min Typ Max Units
(Note 2)
VIInput Clamp Voltage VCC = Min, II = 18 mA 1.5 V
VOH HIGH Level VCC = Min, IOH = Max 2.4 3.1 V
Output Voltage VIL = Max, VIH = Min
VOL LOW Level VCC = Min, IOL = Max 0.35 0.5
Output Voltage VIL = Max, VIH = Min V
IOL = 12 mA, VCC = Min 0.25 0.4
IIInput Current @ Max Input Voltage VCC = Max, VI = 7V 0.1 mA
IIH HIGH Level Input Current VCC = Max, VI = 2.7V 20 µA
IIL LOW Level Input Current VCC = Max, VI = 0.4V 0.4 mA
IOZH Off-State Output Current with VCC = Max, VO = 2.7V 20 µA
HIGH Level Output Voltage Applied VIH = Min, VIL = Max
IOZL Off-State Output Current with VCC = Max, VO = 0.4V 20 µA
LOW Level Output Voltage Applied VIH = Min, VIL = Max
IOS Short Circuit Output Current VCC = Max (Note 3) 20 100 mA
ICC1 Supply Current VCC = Max (Note 4) 6.1 10 mA
ICC2 Supply Current VCC = Max (Note 5) 7.1 12 mA
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DM74LS251
Switching Characteristics
at VCC = 5V and TA = 25°C
Note 6: CL = 5 pF
From (Input) RL = 667
Symbol Parameter to (Output) CL = 45 pF CL = 150 pF Units
Min Max Min Max
tPLH Propagation Delay Time A, B, C 45 53 ns
LOW-to-HIGH Level Output (4 Levels) to Y
tPHL Propagation Delay Time A, B, C 45 53 ns
HIGH-to-LOW Level Output (4 Levels) to Y
tPLH Propagation Delay Time A, B, C 33 38 ns
LOW-to-HIGH Level Output (3 Levels) to W
tPHL Propagation Delay Time A, B, C 33 42 ns
HIGH-to-LOW Level Output (3 Levels) to W
tPLH Propagation Delay Time D to Y 28 35 ns
LOW-to-HIGH Level Output
tPHL Propagation Delay Time D to Y 28 38 ns
HIGH-to-LOW Level Output
tPLH Propagation Delay Time D to W 15 25 ns
LOW-to-HIGH Level Output
tPHL Propagation Delay Time D to W 15 25 ns
HIGH-to-LOW Level Output
tPZH Output Enable Time to Strobe to Y 45 60 ns
HIGH Level Output
tPZL Output Enable Time to Strobe to Y 40 51 ns
LOW Level Output
tPHZ Output Disable Time from Strobe to Y 45 ns
HIGH Level Output (Note 6)
tPLZ Output Disable Time from Strobe to Y 25 ns
LOW Level Output (Note 6)
tPZH Output Enable Time to Strobe to W 27 40 ns
HIGH Level Output
tPZL Output Enable Time to Strobe to W 40 47 ns
LOW Level Output
tPHZ Output Disable Time from Strobe to W 55 ns
HIGH Level Output (Note 6)
tPLZ Output Disable Time from Strobe to W 25 ns
LOW Level Output (Note 6)
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DM74LS251
Physical Dimensions inches (millimeters) unless otherwise noted
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
Package Number M16A
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DM74LS251 3-STATE 1-of-8 Line Data Selector/Multiplexer
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Package Number N16E
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and
Fairchild reserves the right at any time without notice to change said circuitry and specifications.
LIFE SUPPORT POLICY
FAIRCHILD’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 FAIRCHILD
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 (c) whose failure
to perform when properly used in accordance with
instructions for use provided in the labeling, can be rea-
sonably expected to result in a significant injury to the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be rea-
sonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
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