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 74LS266 is comprised of four independent 2-input exclusive-NOR gates with open-collector outputs. The open-collector outputs permit tying outputs together for multiple-bit comparisons.

74LS266 Features

  • Four Independent Two Input exclusive NOR Gates
  • Open Collector Outputs
  • Fast Switching Speeds
  • Operating Temperature to 70°C
  • Standard TTL Switching Voltages

74LS266 Specifications

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

74LS266 Pinout Diagram

74LS266 Pin Description

Pin NoPin NameDescription
1A1Exclusive -NOR Gate 1 Input 1
2B1Exclusive -NOR Gate 1 Input 2
3Y1Exclusive -NOR Gate 1 Output
4Y2Exclusive -NOR Gate 2 Output
5A2Exclusive -NOR Gate 2 Input 1
6B2Exclusive -NOR Gate 2 Input 2
8A3Exclusive -NOR Gate 3 Input 1
9B3Exclusive -NOR Gate 3 Input 2
10Y3Exclusive -NOR Gate 3 Output
11Y4Exclusive -NOR Gate 4 Output
12A4Exclusive -NOR Gate 4 Input 1
13B4Exclusive -NOR Gate 4 Input 2
14VCCPositive Supply


  • Used in error-detecting circuits to detect odd/even parity bits in digital transmission circuits

74LS266 Alternative Equivalent

Download 74LS266 Quad EXCLUSIVE-NOR Gate Datasheet from the link given below.