# What is the exact difference between a latch & a flipflop?

From what I have understood :

1. A Flip Flop is a clocked latch i.e. flip flop = latch + clock
2. Latch continuously checks for inputs & changes the output whenever there is a change in input
3. Flip Flop also continuously checks input, but changes the output time determined by clock. [so, even though if inputs are changed, it may not change the output at the same time]
4. A latch with enable [i.e. gated latch], is different from that of clocked latch.

I am reading from Digital Logic by Morris Mano & Wikipedia.

As far as I understand, the difference is indeed the clock/enable.

A flip-flop samples the inputs only at a clock event (rising edge, etc.)

A Latch samples the inputs continuously whenever it is enabled, that is, only when the enable signal is on. (or otherwise, it would be a wire, not a latch).

• Yet, sometimes (depends on who and where), people may use those terms interchangeably. – Ran G. Apr 7 '13 at 7:33
• but most textbooks explain latch without enable ? – avi Apr 7 '13 at 7:49
• this can make sense for SR-latch, but think about an ungated D-latch -- this is nothing but a wire! The SR is a bit unique since the two inputs (S/R) serve in some sense both as (D/enable), so having S=R=0 is equivalent to having Enable=0. – Ran G. Apr 7 '13 at 7:53
• Oh yes, you are absolutely right. Now it makes sense. So, in textbook they mention ungated SR because it is easy to understand, but in practice gated/enabled latches are used. Right ? – avi Apr 7 '13 at 10:08
• and one more thing, when I say FlipFlop it means it is always clocked & when I say Latch, then it is always with enable. [so, FlipFlop without clock & latch without enable doesn't make any sense] – avi Apr 7 '13 at 12:29

## protected by Community♦Aug 29 '14 at 10:33

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).