74LS251 8-Channel Multiplexer Tri-State


The 74LS series of integrated circuits (ICs) was one of the most popular logic families of transistor-transistor logic (TTL) logic chips. 74LS series is a bipolar, low-power Schottky IC. 74LS251 data selectors/multiplexers contain full on-chip binary decoding to select one-of-eight data sources and feature a strobe-controlled 3-STATE output.

74LS251 Features

  • Tri-State Version of the 74LS151
  • Interface Directly with the System Bus
  • Perform Parallel to Serial Conversion
  • Complementary Outputs Provide True and Inverted Data
  • Standard TTL Switching Voltages

74LS251 Specifications

Supply Voltage4.75 – 5.25Vdc
Maximum Clock Frequency40Mhz
Power Dissipation2mW/gate @100kHz
Minimum Output Current8mA
Propagation Delay10nS
Fan Out (TTL Loads)20

74LS251 Pinout Diagram

74LS251 Pin Description

Pin NoPin NameDescription
1I3Data Input 3 Of Multiplexer
2I2Data Input 2 Of Multiplexer
3I1Data Input 1 Of Multiplexer
4I0Data Input 0 Of Multiplexer
5Zoutput Pin Of Multiplexer
6Z’Invert Output Pin Of Multiplexer
7E0Enable Output
9S2Data Select Pin
10S1Data Select Pin
11S0Data Select Pin
12I7Data Input 7 Of Multiplexer
13I6Data Input 6 Of Multiplexer
14I5Data Input 5 Of Multiplexer
15I4Data Input 4 Of Multiplexer
16VCCPositive Supply


  • Multiple data can be transmitted using a single line.

74LS251 Alternative Equivalent

74LS253, 74LS257

Download 74LS251 8-Channel Multiplexer Tri-State Datasheet from the link given below.