Question

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Master-slave J-K flip-flop is free from race around condition. Reason (R): Master-slave uses two J-K flip-flops. In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Race-around condition occurs in JK flip-flops when: \[ J=K=1 \] Master-slave configuration removes this problem by using two cascaded flip-flops operating on opposite clock phases.

Answer 1

The Correct Option is A

Concept: Race around condition occurs in level-triggered JK flip-flops when: \[ J=K=1 \] and the clock pulse width is larger than the propagation delay. In such a situation:
• Output toggles repeatedly
• Final state becomes uncertain A master-slave JK flip-flop eliminates this problem using:
• One master flip-flop
• One slave flip-flop These operate on opposite clock phases, preventing multiple toggling during a single clock pulse.

Step 1: Analyze Assertion (A). Assertion states: Master-slave JK flip-flop is free from race around condition. This statement is correct. The master section captures input during one clock phase, while:
• Slave remains disabled During the opposite clock phase:
• Slave updates output
• Master becomes inactive Thus repeated toggling is prevented. Hence: \[ (A)\text{ is correct} \]

Step 2: Analyze Reason (R). Reason states: Master-slave uses two JK flip-flops. This statement is also correct. A master-slave configuration indeed contains:
• Master JK flip-flop
• Slave JK flip-flop connected in cascade. Hence: \[ (R)\text{ is correct} \]

Step 3: Determine whether Reason explains Assertion. The reason correctly explains the assertion because:
• Using two cascaded JK stages operating on opposite clock phases prevents continuous toggling.
• Therefore race-around condition is eliminated. Hence:
• Both Assertion and Reason are correct.
• Reason correctly explains Assertion.

Step 4: Write the final answer. Therefore, the correct option is: \[ \boxed{(A)\ \text{Both (A) and (R) are correct and (R) is the correct explanation of (A)}} \]