FLIP-FLOP
Finite state machines, sequential logic circuits, timing and memory devices use a binary digit or 1 bit of data (either 0 or 1). Flip-flops are used to remember the previous state of the machine and this data is used by logic circuits to calculate the next state. Flip flops are basically synchronous bi-stable devices that work depending on the clock signal applied to them. The output changes based on the clock signal trigger hence the term synchronous.
How they work:
The working of a flip-flop can be mainly attributed to the clock. Much depends on the clock signal trigger for the desired output. The common elements of a flip-flop include a clock signal, input signals and an output signal. When a pulse is given to the clock, the flip-flop either changes or retains its output signal. A flip-flop uses square types of waveforms.
Flip-flops are generally categorized into four basic types like T flip-flop, S/R flip-flop, J/K flip-flop and D flip-flop.
§ The T type is a toggle flip-flop used in counting applications.
§ S-R flip-flop is a set/reset type that changes or resets its state based on the strobing.
§ J-K type is a universal flip-flop used as a counter.
§ D flip-flop is a delay type in which the data is sent to the output, one clock cycle after it is received at the input.
Other types of flip-flops include CMOS and Meta-stable flip-flops.
Some of the important operating characteristics to consider when selecting a flip-flop are listed below.
§ Propagation Delay Time - is the interval of time between the input and the output.
§ Set-Up Time - is the minimum interval required for the logic levels to be maintained constantly on the inputs.
§ Maximum Clock Frequency - is the highest rate at which a flip-flop can be triggered.
§ Power Dissipation - is the total power consumption of the device.
Flip-flops are profoundly used in applications where use of a counter is necessary. Other applications of flip-flops include frequency division, parallel data storage etc. ADF (aircraft automatic direction finder systems), PC, microprocessor and micro-controller-based kits, water-level sensor, electronic switching circuit etc also use flip-flops in their components.
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