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Sequential Circuits
Author of this note Mr. K. Prasad BSc from University of Calicut, MSc from university of Delhi, and M.B.A from IGNOU Delhi, These notes were prepared during my teaching session for under graduate students (11th and 12th class) of my school Physics department. This note is helpful for under graduate students and junior level graduates I declare that these notes are my original works based on my knowledge in physics and the books mentioned below are the reference books I used for preparing these notes.
Table of contents, (1)Sequential circuits, (2)Overview of Flip Flops, (3)Flip flop v/s Latch, (4)SR Flip Flop, (5)JK Flip-flop, (6)D Flip Flop, (7)T Flip Flop, (8)Applications of Flip-Flops, (9)Preset and clear, (10)Race around condition in JK flip flop, (11)M/S JK Flip-Flop, Reference Books: Digital Principles and Applications, A.P.Malvino, D.P.Leach and Saha, 7 th^ Ed., 2011, Tata McGraw Fundamentals of Digital Circuits, Anand Kumar, 2 nd Edn, 2009, PHI Learning Pvt. Ltd Digital Circuits and systems, Venugopal, 2011, Tata McGraw Hill Digital Electronics G K Kharate ,2010, Oxford
The most commonly used sequential circuits are synchronous —their action is controlled by a sequence of clock pulses. The clock pulses are created by a clock generator circuit. The clock pulses are applied to all the sequential elements, thus causing them to operate in synchrony. Overview of Flip Flops, A flip flop is an electronic circuit with two stable states that can be utilized to store paired information. The put away information can be changed by applying shifting data inputs. Flip- flops and latches are major structure blocks of computerized gadgets systems utilized in PCs, correspondences, and numerous different kinds of systems. Both are utilized as information data storage components. It is the essential storage component in consecutive rationale. On the whole, we should explain the contrast between a latch and a flip-flop. Flip flop v/s Latch, The essential contrast between a latch and a flip-flop is a gating or timing system. In basic words. Flip flop is edge-set off and a lock is level set off, For instance, let us discuss SR lock and SR flip-flops. In this circuit when you Set S as dynamic the result Q would be high and Q' will be Low. This is regardless of whatever else. (This is a functioning low circuit so dynamic here implies low, however for a functioning high circuit dynamic would mean high)
A flip-flop, on the other hand, is synchronous and is also known as a gated or clocked SR latch. In this circuit diagram, the output is changed (i.e. the stored data is changed) only when you give an active clock signal. Otherwise, even if the S or R is active the data will not change. Let’s look at the types of flip-flops to understand better. SR Flip Flop, There are significantly 4 sorts of flip-flops, with the most well-known one being SR flip-flop. This basic flip-flop circuit has set information (S) and a reset input (R). In this system, when you Set "S" as dynamic the result "Q" would be high and "Q'" will be low. When the results are laid out, the wiring of the circuit is kept up with until "S" or "R" go high, or power is switched off. As displayed above, it is the least complex and most simple to explain. The two results, as displayed above, are the
takes the worth of J at the following clock edge. In the event that J and K are both low, no change happens. In the event that J and K are both high at the clock edge, the result will flip from one state to the next. JK Goes back and forth can work as Set or Reset Goes back and forth. J K Q Q’ 0 0 0 0 0 1 0 0 1 0 0 1 1 1 0 1 0 0 1 1 0 1 1 0 1 0 1 1 1 1 1 0 D Flip Flop, D flip-flop is a superior elective that is extremely well known with computerized gadgets. They are normally utilized for counters and shift-registers and information synchronization. In this, the output can be only changed at the clock edge, and if the input changes at other times, the output will be unaffected.
Clock D Q Q’ ↓ » 0 (^0 0 ) ↑ » 1 (^0 0 ) ↓ » 0 (^1 0 ) ↑ » 1 (^1 1 ) The change of state of the output is dependent on the rising edge of the clock. The output (Q) is same as the input and can only change at the rising edge of the clock. T Flip Flop, A T flip-flop resembles a JK flip-flop. These are essentially a solitary input variant of JK flip flops. This adjusted type of JK flip-flop is gotten by interfacing the two data sources J and K together. It has just a single contribution alongside the clock input. These flip-flops are called T flip-flops because of their ability to complement its state (i.e.) Toggle, hence the name Toggle flip-flop.
Race around condition in JK flip flop, Race Around Condition In JK Flip-flop – For J-K flip-flop, if J=K=1, and if clk=1 for a long period of time, then Q output will toggle as long as CLK is high, which makes the output of the flip-flop unstable or uncertain. This problem is called race around condition in J-K flip-flop. Race around condition can be eliminated using the master-slave flip- flop. Master-Slave flip-flop is the cascaded combination of two flip-flops among which the first is designated as master flip-flop while the next is called slave flip-flop. M/S JK Flip-Flop, The Master-Slave Flip-Flop is basically a combination of two JK flip-flops connected together in a series configuration. Out of these, one acts as the “master” and the other as a “slave”.
