DM74LS257BN

DM74LS257BN Datasheet

DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers

Part	Datasheet
DM74LS257BN	DM74LS257BN (pdf)

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DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers These Schottky-clamped high-performance multiplexers feature 3-STATE outputs that can interface directly with data lines of bus-organized systems. With all but one of the common outputs disabled at a high impedance state , the low impedance of the single enabled output will drive the bus line to a HIGH or LOW logic level. To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output enable circuitry is designed such that the output disable times are shorter than the output enable times. This 3-STATE output feature means that n-bit paralleled data selectors with up to 258 sources can be implemented for data buses. It also permits the use of standard TTL registers for data retention throughout the system. s 3-STATE versions LS157 and LS158 with same pinouts s Schottky-clamped for significant improvement in A-C performance s Provides bus interface from multiple sources in high-performance systems s Average propagation delay from data input 12 ns s Typical power dissipation 50 mW Ordering Code: Order Number Package Number Package Description DM74LS257BM M16A 16-Lead Small Outline Integrated Circuit SOIC , JEDEC MS-012, Narrow DM74LS257BN N16E 16-Lead Plastic Dual-In-Line Package PDIP , JEDEC MS-001, Wide Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code. Connection Diagram Logic Diagram Function Table Output Control H = HIGH Level L = LOW Level Inputs Select A X = Don’t Care Z = High Impedance off Output Y LS257 Z L H L H 1999 Fairchild Semiconductor Corporation DS006417 DM74LS257B Absolute Maximum Ratings Note 1 Supply Voltage Input Voltage Operating Free Air Temperature Range 0°C to +70°C Storage Temperature Range −65°C to +150°C 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 tables are not guaranteed at the absolute maximum ratings. The Recommended Operating Conditions table will define the conditions for actual device operation. Recommended Operating Conditions VCC VIH VIL IOH IOL TA Parameter Supply Voltage HIGH Level Input Voltage LOW Level Input Voltage HIGH Level Output Current LOW Level Output Current Free Air Operating Temperature DC Electrical Characteristics Parameter Conditions Typ Min Note 2 Input Clamp Voltage VCC = Min, II = −18 mA HIGH Level Output Voltage VIL = Max, VIH = Min LOW Level Output VIL = Max, VIH = Min Voltage IOL = 12 mA, VCC = Min Input Current Max VCC = Max, Select Input Voltage

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DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers

DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers

These Schottky-clamped high-performance multiplexers feature 3-STATE outputs that can interface directly with data lines of bus-organized systems. With all but one of the common outputs disabled at a high impedance state , the low impedance of the single enabled output will drive the bus line to a HIGH or LOW logic level. To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output enable circuitry is designed such that the output disable times are shorter than the output enable times.

This 3-STATE output feature means that n-bit paralleled data selectors with up to 258 sources can be implemented
for data buses. It also permits the use of standard TTL registers for data retention throughout the system.
s 3-STATE versions LS157 and LS158 with same pinouts s Schottky-clamped for significant improvement in A-C
performance s Provides bus interface from multiple sources in
high-performance systems s Average propagation delay from data input 12 ns s Typical power dissipation 50 mW
Ordering Code:

Order Number Package Number

Package Description

DM74LS257BM

M16A
16-Lead Small Outline Integrated Circuit SOIC , JEDEC MS-012, Narrow

DM74LS257BN

N16E
16-Lead Plastic Dual-In-Line Package PDIP , JEDEC MS-001, Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.

Connection Diagram

Logic Diagram

Function Table

Output Control

H = HIGH Level L = LOW Level

Inputs

Select A

X = Don’t Care Z = High Impedance off

Output Y

LS257

Z L H L H
1999 Fairchild Semiconductor Corporation DS006417

DM74LS257B

Absolute Maximum Ratings Note 1

Supply Voltage

Input Voltage

Operating Free Air Temperature Range 0°C to +70°C

Storage Temperature Range
−65°C to +150°C

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 tables are not guaranteed at the absolute maximum ratings. The Recommended Operating Conditions table will define the conditions for actual device operation.

Recommended Operating Conditions

VCC VIH VIL IOH IOL TA

Parameter Supply Voltage HIGH Level Input Voltage LOW Level Input Voltage HIGH Level Output Current LOW Level Output Current Free Air Operating Temperature

DC Electrical Characteristics

Parameter

Conditions

Typ Min

Note 2

Input Clamp Voltage

VCC = Min, II = −18 mA

HIGH Level Output Voltage

VIL = Max, VIH = Min

LOW Level Output

VIL = Max, VIH = Min

Voltage

IOL = 12 mA, VCC = Min

Input Current Max

VCC = Max,

Select

Input Voltage

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Datasheet ID: DM74LS257BN 513785