# Which is slow among the two? Latches or Flip-Flops?

I have a question regarding latches and flip-flops. Which of them, is faster? Please explain me this with a suitable reason.

• Which of them would you guess is faster, and why? Commented Apr 21, 2020 at 17:52
• Please define what you mean by "faster". Commented Apr 21, 2020 at 18:18
• Well, I guest latches to be faster than flip flops.@Justin Commented Apr 21, 2020 at 18:19
• I am asking as a general overview of operation @ElliotAlderson Commented Apr 21, 2020 at 18:20
• I’m voting to close this question because it does not show any prior research effort. Commented Apr 21, 2020 at 18:43

Latch triggers have 5% efficiency, since it takes 95% of the time for the latch trigger to settle in a logic 0 or logic 1, before the fluctuating of the signal stops. This is do the technology with wich they are built. On latch triggers you detect the voltage level, which has transient processes and settles after 95% of the time.

Flip-flop triggers are switched by front, rising or falling, they have 100% efficiency based only on the time necessary for the front to rise or fall.

• Transparent D Latches, freeze the data immediately when E is low. And it's pretty fast. As soon as a logic low is seen on pin E, the latch is latched. If you fall time is 2ns, it's the same as an edge falling time of 2ns (+ propagation delay). I don't understand why it's less efficient. Commented Apr 21, 2020 at 21:02
• Lets consider the situation, 95% of 2nS to be wasted or the signal to change at the start of the 2nS? Commented Apr 21, 2020 at 21:15
• But why do you think it's triggered during the slope and not only after the logic asserted a passing between two states? Commented Apr 21, 2020 at 21:27
• But flip-flops are made from latches. This answer makes no sense to me. Commented Apr 21, 2020 at 21:58
• I am a hardware developer originally and I develop microprocessor systems. I don't want to quote the whole theory or spend my time in arguments. I see someone has downvoted my answer already. I have seen wrong answers with 13000 upvotes. Flip flops will always be faster, no matter what you see in the book. Commented Apr 21, 2020 at 23:16

You have to look at the propagation delay time in the datasheets of several models of latches and several models of flip-flops (care to check for D and J-K Flip-Flops).

Then put the values from the datasheets in an excell table and draw a statistic graph.