![]() All sequential circuits are operated with clock signal. The reciprocal of the time period of clock signal is known as the frequency of the clock signal. In this case, the time period will be equal to sum of ON time and OFF time. ![]() This pattern repeats with some time period. This signal stays at logic High (5V) for some time and stays at logic Low (0V) for some other time. In the above figure, train of pulses is considered as clock signal. This clock signal is shown in the following figure. We can represent the clock signal as train of pulses, when ON time and OFF time are not same. In this case, the time period will be equal to either twice of ON time or twice of OFF time. This signal stays at logic High (5V) for some time and stays at logic Low (0V) for equal amount of time. N the above figure, square wave is considered as clock signal. We can represent the clock signal as a square wave, when both its ON time and OFF time are same. Clock signalĬlock signal is a periodic signal and its ON time and OFF time need not be the same. In this section, let us discuss about the clock signal and types of triggering one by one. Therefore, the outputs of synchronous sequential circuits are in synchronous with either only positive edges or only negative edges of clock signal. That means, all the outputs of synchronous sequential circuits change (affect) at the same time. If all the outputs of a sequential circuit change (affect) with respect to active transition of clock signal, then that sequential circuit is called as Synchronous sequential circuit. Therefore, most of the outputs of asynchronous sequential circuits are not in synchronous with either only positive edges or only negative edges of clock signal. That means, all the outputs of asynchronous sequential circuits do not change (affect) at the same time. If some or all the outputs of a sequential circuit do not change (affect) with respect to active transition of clock signal, then that sequential circuit is called as Asynchronous sequential circuit. Outputs depend on both present inputs and present state.įollowing are the two types of sequential circuits − Some sequential circuits may not contain combinational circuits, but only memory elements.įollowing table shows the differences between combinational circuits and sequential circuits. Therefore, sequential circuits contain combinational circuits along with memory (storage) elements. Previous output is nothing but the present state. The output(s) of sequential circuit depends not only on the combination of present inputs but also on the previous output(s). This sequential circuit contains a set of inputs and output(s). The following figure shows the block diagram of sequential circuit. All these circuits have a set of output(s), which depends only on the combination of present inputs. We discussed various combinational circuits in earlier chapters. They are reliable and efficient, and can be used in a variety of applications. Sequ ential circuits are essential components of digital devices and are used to control the logic of a system. Sequ ential circuits are also used to create state machines, which are used to control the behavior of a digital device in response to its inputs. They can be used to create counters and shift registers, which enable a device to store and manipulate data. Join the vibrant Electrical & Electronics Engineers community This information is then used to determine the state of the circuit and to control the output. The memory element of a sequential circuit is typically a flip – fl op, which stores one bit of information. Sequential circuits are used to control the operation of devices such as computers, televisions, and other digital systems. ![]() ![]() They are used to store data or instructions, to perform logical operations, and to control the flow of data within a system. Sequential circuits are often used to control operations in digital systems. ![]()
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