Minimum number of flip flops required for mod-12 ripple counter is

Concept:

For a counter with ‘n’ flip flops:

• The total number of states = 2ⁿ (0 to 2ⁿ – 1)
• The largest number that can be stored in the counter = 2ⁿ – 1

To construct a counter with any MOD number, the minimum number flip flops required must satisfy:

Modulus ≤ 2ⁿ

Where n is the number of flip-flops and is the minimum value satisfying the above condition.

Note: A MOD-N counter is also called as a divide by N counter as the input frequency is divided by the number of states of the counter.

Calculation:

Number no. of flip – flops are required to construct mod-12 counter, must satisfy:

2ⁿ ≥  12

The minimum value of n satisfying the above is:

n = 4