74LS136B

Updated: 2026-09-12

Overview

The 74LS136B is a member of the 74LS series of transistor-transistor logic (TTL) integrated circuits. It contains four independent 2-input exclusive-OR (XOR) gates with open-collector outputs, making it particularly useful in digital systems where wired-OR connections are required. The device operates with standard 5V TTL logic levels and is characterized by its low power consumption compared to earlier TTL generations. As part of the 74LS (Low-power Schottky) family, it offers improved speed-power product over basic 74 series devices.

Structure and Working Principle

Each XOR gate in the 74LS136B package implements the logical function Y = A ⊕ B, where the output is high only when the inputs are different. The open-collector outputs require external pull-up resistors when used in standard logic applications. The internal architecture uses Schottky clamped transistors to prevent saturation, providing faster switching times than standard TTL. The open-collector configuration allows for wired-AND connections between multiple outputs and provides flexibility in interfacing with different voltage levels.

Key Features

The 74LS136B offers several notable characteristics: four independent XOR gates in a single 14-pin package, typical propagation delay of 15ns, and power dissipation of about 10mW per gate. Open-collector outputs enable bus sharing and level shifting capabilities. The device features improved noise immunity compared to earlier TTL generations and operates across the industrial temperature range (-40°C to +85°C).

Application Areas

Common applications include arithmetic logic units (ALUs), parity generators/checkers, phase comparators, and error detection circuits in digital systems. The 74LS136B is frequently used in industrial control systems, computer interfaces, and communication equipment. Its open-collector outputs make it suitable for driving indicators, relays, or other higher-current devices beyond standard logic levels.

Maintenance and Precautions

When working with 74LS136B ICs, observe standard ESD precautions during handling and installation. Avoid exceeding the absolute maximum ratings (7V supply voltage, 5.5V input voltage). Ensure proper decoupling capacitors are installed near the power pins in actual circuits. When using open-collector outputs, select appropriate pull-up resistor values based on required switching speed and power consumption.

B2B Procurement Guide

When procuring 74LS136B ICs, verify the manufacturer's part number (SN74LS136B for Texas Instruments, DM74LS136B for National Semiconductor) and packaging options (DIP, SOIC). Consider ordering from authorized distributors for guaranteed authenticity, especially for critical applications. Minimum order quantities typically range from single units for prototyping to reels of 2,000 for production. Lead times vary from stock availability to 8-12 weeks for non-standard packaging.