3. What are Counters?
Counter is a sequential circuit
A digital circuit which is used for a counting pulses is known counter
Conter is widest application of flip-flops. It is a group of flip-flops with a clock
signal applied
4. Types of counters
There are two types of counters which way of they are clocked . They are
synchronous counters and asynchronous counters or ripple counters
In synchronous counters there are continuous clock input signals with flip-
flops used to produce the output
In asynchronous counters there are different clock signals to produce the
output
5.
6. Asynchronous counters
There are several types of asynchronous counters
Some of them are two bit asynchronous counters, three bit asynchronous
counters, asynchronous decade counters etc
11. Delay of asynchronous counters
Unfortunately one of the main disadvantages with asynchronous counter is
that there is a small delay between the arrival of the clock pulse at its input
and it being presents at its output
It happens because each flip flop does not changed at the same time
The propagation delay of each flip-flop adds together to give a total
propagation delay for the counter
Total propagation delay of asynchronous counter should be less than period of
external clock pulse
