Two types of edge triggered flip flop
In this chapter, we implemented various flip-flops by providing the cross coupling between NOR gates. Hence, T flip-flop can be used in counters. The output of T flip-flop always toggles for every positive transition of the clock signal, when input T remains at logic High (1). $$\Rightarrow Q\left ( t+1 \right )=T\oplus Q\left ( t \right )$$ Therefore, the simplified expression for next state Q(t + 1) is The maximum possible groupings of adjacent ones are already shown in the figure. The three variable K-Map for next state, Q(t + 1) is shown in the following figure. Present Inputsīy using three variable K-Map, we can get the simplified expression for next state, Q(t + 1). The following table shows the characteristic table of SR flip-flop. So, SR flip-flop can be used for one of these three functions such as Hold, Reset & Set based on the input conditions, when positive transition of clock signal is applied. Here, Q(t) & Q(t + 1) are present state & next state respectively. The following table shows the state table of SR flip-flop. But, this flip-flop affects the outputs only when positive transition of the clock signal is applied instead of active enable. The operation of SR flipflop is similar to SR Latch. DET flip-flop is considered as a device level. This circuit has two inputs S & R and two outputs Q(t) & Q(t)’. Parallelism can be applied at different levels of a design: system, architecture, circuit/logic, device, etc. The circuit diagram of SR flip-flop is shown in the following figure. Whereas, SR latch operates with enable signal. SR flip-flop operates with only positive clock transitions or negative clock transitions. In this chapter, let us discuss the following flip-flops using second method. In second method, we can directly implement the flip-flop, which is edge sensitive. So that the combination of these two latches become a flip-flop.
In first method, cascade two latches in such a way that the first latch is enabled for every positive clock pulse and second latch is enabled for every negative clock pulse. We can implement flip-flops in two methods. Let’s Look at the circuit of Active High SR Flip Flop and work at it in Proteus ISIS. We know that Q is always opposite to Q’ hence we get the output as expected. When the S is 0, the output Q is 1 and vise versa. Those are the basic building blocks of flip-flops. The Active High SR Flip Flops are the one in which the Set input and the output terminal Q collaborate with each other. In previous chapter, we discussed about Latches. SN74LVC2G74DCUT Datasheet(PDF) 2 Page - Texas Instruments: Part No.