74LS181 Arithmetic Logic Unit/Function Generator


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. The 74LS181 is an arithmetic logic unit (ALU} function generator that has a complexity of 75 equivalent gates on a monolithic chip. These circuits perform 16 binary arithmetic operations on two 4-bit words

74LS181 Features

  • Full Look-Ahead for High-Speed Operations on Long Words
  • Input Clamping Diodes Minimize Transmission-Line Effects
  • Darlington Outputs Reduce Turn-Off Time

74LS181 Specifications

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

74LS181 Pinout Diagram

74LS181 Pin Description

Pin NoPin NameDescription
1B0Active low Operand Input B0
2A0Active low Operand Input
3S3Function Select Input S3
4S2Function Select Input S2
5S1Function Select Input S1
6S0Function Select Input S0
7CnCarry Input
8MMode Control Input
9F0Function Output F0
10F1Function Output F1
11F2Function Output F2
12GNDGround Pin
13F’3Function Output F’3
14A=BComparator Output
15P’Active low carry propagate
16Cn+4Carry Output
17G’Active low-carry generator
18B’3Active low Operand Input B’3
19A’3Active low Operand Input A’3
20B’2Active low Operand Input B’2
21A’2Active low Operand Input A’2
22B’1Active low Operand Input B’1
23A’1Active low Operand Input A’1
24VCCChip Supply Voltage


  • Enables computers to perform mathematical operations on binary numbers

Download the 74LS181 Arithmetic Logic Unit/Function Generator Datasheet from the link given below.