Types Of Counter || Registers and Counters || Bcis Notes

Types Of Counter

The main purpose of the counter is to record the number of occurrence of some input. There are many types of counter both binary and decimal.

Counter

The counter is a sequential circuit. A digital circuit which is used for counting pulse is known as a counter. It is the widest application of flip-flops. It is a group of a flip-flop with clock signal applied. Counter are two types.
– Asynchronous counter
– Synchronous counter

Difference between Asynchronous and Synchronous

Asynchronous counter OR Ripple counter	Synchronous counter
Flip-flips are connected in a such a way that the output of first flip-flop drives the clock of next flip-flop.	There is no connection between the output of the first flip-flop and clock of next flip-flop.
Flip-flops are not clocked simultaneously.	All the flip-flops are clocked simultaneously.
Less number of logic gates are required.	A large number of logic gates are required.
Speed is slow as the clock is propagated though no: of the stage.	Speed is high as the clock is given at the same time.
It is slow in operation.	It is faster than a ripple counter in operation.
Low cost	High cost

Features of Asynchronous counter.

These are very simple in design.
As it’s designed is simple they use less number of logic gates to construct asynchronous counter.
Operation of the asynchronous counter is very low as compare to synchronous counter.

Types of Asynchronous counter.

UP counter.
Down counter.
Equal Up-down counter.
Ripple BCD counter.

Two-bit asynchronous counter

The figure shows that the two-bit counter connected for the asynchronous counter. Notice that the clock is applied to the clock input of only first flip-flop, which is always the less significant bit. The second flip-flop triggered by the (Ǭ0) output of the first flip-flop edge of (Ǭ0) output of the flip-flop. Because of inherent propagation delay time through a flip-flop. A transition of the input clock pulse and transition of Ǭ0 output can never exactly occur at the same time. Therefore two flip-flops are simultaneously triggered, so the counter operation is asynchronous which is also called ripple counter.

Binary state sequence table for the counter