Triggering Of Flip-Flops
We already know that a flip-flop has two stable states. A flip-flop changes from one state to another and comes back to its original state. Now how can we change the state of the flip-flop? The state of the flip-flop can be changed by applying a momentary change to the Input signal. This momentary change is called triggering of a flip-flop. There are clocked flip-flops which are triggered by the pulse generated by clocking signal. A clock pulse is usually a square wave which has 0 as its initial value and goes momentarily to 1 and returns back to 0.
Triggering of flip-flops can be classified into:
• Level Triggering
• Edge Triggering
Level triggered flip-flops are dependent on the period of the pulse applied to it. It is further classified into two types.
• Positive Level Triggering
• Negative Level Triggering
If a flip-flop changes its state when the clock pulse applied is positive then it is called as positive level triggering.
On the contrary, if the flip-flop changes its state when the clock pulse applied is negative then it is called negative level triggering.
The edge triggered flip flops changes state either at positive edges or negative edges of the clock pulse applied and accordingly they are classified into Positive edge triggered Flip flops and Negative edge triggered flip flops. A positive or rising transition is achieved from positive edge flip flops and negative or falling transition is achieved from negative edge flip flops. In the next article let us discuss the basic circuit of flip-flop and types of flip-flops that are being used in digital circuits for various applications.