SN74LS109 Dual J-Kbar Positive-Edge-Triggered Flip-Flop with Preset and Clear – 16-Pin DIP

The SN74LS109 is a specialized dual flip-flop that provides high-speed logic and versatile control options. Its defining characteristic is the J-Kbar input configuration. In a standard J-K flip-flop, you must pull both pins high to toggle; in the 74LS109, you pull J high and Kbar low to achieve the same result. This makes the chip particularly useful for interfacing with sensors or logic gates that output inverted signals. This IC is a staple in sequential logic design, used for building counters, shift registers, and synchronization circuits. Because it includes both Preset and Clear inputs, it is incredibly easy to "start" a system at a known state (either 0 or 1). Its positive-edge triggering ensures that the output only changes when the clock signal transitions from low to high, preventing accidental triggers from unstable signals. The 16-pin DIP through-hole package is rugged and industry-standard, making it perfect for repairing legacy computer hardware, building educational logic trainers, or designing custom industrial timing controllers. Whether you need a simple toggle switch or a complex frequency divider, the SN74LS109 offers a professional and robust logic solution.

Key Features:

Unique J-Kbar Logic Unlike standard J-K flip-flops, the second input is active-low (Kbar). This allows the chip to act as a D-type flip-flop by simply tying the J and Kbar inputs together.

Positive-Edge Triggering Data is transferred from the inputs to the outputs on the rising edge of the clock pulse, ensuring high timing precision.

Direct Preset and Clear Inputs Features asynchronous active-low Set and Reset pins that override the clock, allowing for immediate initialization of the flip-flop state.

Low-Power Schottky (LS) Technology Offers a professional balance between high-speed switching and low power consumption for 5V systems.

High Noise Immunity Specifically designed to maintain stable logic states in environments with electrical noise, such as industrial control panels.