Definition of a JK Flip-Flop

JK flip-flops are highly adaptable and widely used circuits in the domain of edge-triggered and master/slave multivibrators. These flip-flops are implemented in different modes and carry almost the same functions as SR flip-flops do, with tiny exceptions in architecture and functioning. Moreover, JK flip-flops have the benefit of their unambiguous state and can also be transformed into other flip-flop circuits. JK flip-flops are used in different digital, computational and control processes.

Architecture

A basic JK flip-flop has architecture based on four interconnected NAND (negative-AND) gates, with two of them being cross-attached to each other. Identical to the SR, the JK flip-flop has two inputs, a triggering clock-pulse input and two outputs. The only architectural difference between the SR and JK flip-flops is the connection of first and second outputs to the second and first input NAND gates, respectively. This difference serves as the basis for the toggling state in JK flip-flops.

Functions

The JK flip-flop is a clock-based circuit that needs a clock signal at input to get activated. With both inputs reset, there is no change in the state of a JK flip-flop. At first input reset and second input set, the state turns to reset. Similarly, at first input set and second input reset, the resulting state becomes set. With both first and second inputs turned set, the flip-flop goes into a closure or toggling state. The toggle stage refers to the switching of state from one level to another, continuously. Here, set and reset represents high and low--0 and 1 respectively.

Categories

There are two common categories of JK flip-flops: edge-triggered and pulse-triggered (master/slave) flip-flops. Pulse-triggered JK flip-flops are activated by the leading edge of the clock pulse and do not change their state until the trailing edge arrives. Edge-triggered flip-flops change their state at either the leading or trailing edge of the clock pulse. Due to the dynamic functionality of edge-triggered JK flip-flops, pulse-triggered JK flip-flops are now obsolete.

Operational Characteristics

Operational characteristics are the basic parameters and requirements defined for a JK flip-flop to work smoothly. These characteristics are either standard or variable, depending upon the manufacturer. For instance, a JK flip-flop requires a standard supply voltage ranging from -5 V to 5 V. But operational characteristics like propagation delay, operating current, hold time, setup time, clock frequency, power consumption, pulse width, sink current and source current vary in packages from different manufacturers.

Applications

Due to their versatility, JK flip-flops have a wide range of applications. They are most commonly used in making digital mod-x counters and frequency dividers. Other applications include shift registers, order detectors and serial and parallel data transmission. JK flip-flops can also be modified into D and T flip-flop circuits to perform required operations. These modifications are usually found in microcontroller and microprocessor circuits, which contain hundreds of these flip-flops.

Packages

JK flip-flops are mostly used within an integrated circuit package. Usually they come in the form of standard packages from different manufacturers. These packages are classified according to the negative and positive edge-triggered JK flip-flop families. Packages like the 74HCxx, 74LCxx and SN74xx series are the most common negative edge-triggered JK flip-flops available. Common positive edge-triggered packages include the 74LSxx and 74HCxx family series.

References

• HyperPhysics: J-K Flip Flop
• WearCam.org: Flip-Flops