digital logic

Question

A ripple counter is made with three positive edge triggered flip-flops. If the output of previous lower significant bit flipflop is used as a triggering clock pulse of the next higher significant bit flip-flop, then the resultant counter is a

 A MOD 3 up counter

B MOD 3 down counter

C MOD 8 bit up counter

D MOD 8 down counter

 

since all are positive edge triggered flip flops ,so shouldn't the answer be mod 8 up counter??

Comments

Dharmendra Lodhi The basic flip flop that we used in Asynchronous counters is T  Flip Flops

If in the question nothing is mention then always we take T flip flop

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why not mod-3 counter??

given that it is ripple counter.

Ripple counter means it's mod number = 2ⁿ .

 

@Dharmendra Lodhi

here no information about which flip-flop e have to take either D or J-K  or T

Implementation of Ripple counter ( i mean FF's used ) is transparent to users,

∴ you can form a ripple counter using only D flipflops or using only T flipflops or using only J-K flipflops, but note that the circuit may differ by choosing FF.

Generally, Ripple counter is asynchronous counters ===> uses T- FF by default, therefore for given question, it is mod-8 down counter.

 

can you elaborate little bit more

with diagram

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thanks, got it!

i implemented it using d flip flops & got the following states:-

001-->000-->011-->010-->101-->100-->111-->110-->001

hence mod 8 down counter because of the same polarities.