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. 74LS12 3-INPUT NAND GATE (OPEN COLLECTOR) containing three independent 3-input NAND gates with open-collector outputs. The open-collector outputs require pull-up resistors to perform correctly. They may be connected to other open-collector outputs to implement active-low wired-OR or active-high wired-AND functions. Open-collector devices are often used to generate higher VOH levels.

74LS12 Features

  • Three Independent NAND Gates
  • Standard Pin Configuration
  • Fast Switching Times
  • Operating Temperature up to 70°C
  • Standard TTL Switching Voltages

74LS12 Specifications

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

74LS12 Pinout Diagram

74LS12 Pin Description

Pin NoPin NameDescription
1A1NAND Gate 1 Input 1
2B1 NAND Gate 1 Input 2
3A2 NAND Gate 2 Input 1
4B2 NAND Gate 2 Input 2
5C2 NAND Gate 2 Input 3
6D2 NAND Gate 2 Output
8D3 NAND Gate 3 Output
9A3 NAND Gate 3 Input 1
10B3 NAND Gate 3 Input 2
11C3 NAND Gate 3 Input 3
12D1 NAND Gate 1 Output
13C1 NAND Gate 1 Input 3
14VCCPositive Supply

74LS12 Circuit


  • LDR
  • Freezer warning buzzer circuits
  • Automatic temperature control circuits

74LS12 Alternative Equivalent

74LS03, 74LS10,74LS01

Download 74LS12 3-INPUT NAND GATE (OPEN COLLECTOR) Datasheet from the link given below.