Race around condition is associated with ______.

Explanation:

1. Practically, we don’t get toggling in sequential circuits. Since clock pulse is more than the propagation delay, so within one clock pulse the output will keep on toggling again and again and it may become indeterminate. This is known as the race-around condition.

2. Race Around condition occurs because of the feedback connection.

Race around condition (RAC)

• Race around condition occurs only in level-triggered flip flop
• Level triggered is transparent.
• Even though input is constant, output continuously toggles. Changes for some time continuously.

• RAC is when J = 1 and K = 1 [flip flop in toggling mode] and tp > tff
• Output toggles many times instead of once in one clock pulse. It is undesirable and called as “Race Around Condition”

Race around condition can further be explained with SR latch example:

A clocked latch is shown below

• When S = R = CLK = 1
• The outputs Q and Q’ are maintained at logic 0
• There is no race around condition

• However, when clocked SR latch is converted to JK flip flop by providing feedback as shown below

• Then when J = K = CLK = 1, then the output Q and Q’ keeps toggling between 0 and 1, thus, there is a race around condition there

So we can conclude that racing condition occurs in sequential circuits with the level-triggered clock.

Hence option (2) is the correct answer.

Important Points

The race around condition can be eliminated by using the following methods:

• Increasing the delay of flip-flop
• Use of edge-triggered flip-flop
• Use of master-slave JK flip flop

The Master-slave configuration is used in a flipflop to eliminate the race-around condition but not to store two bits of information.