confusion between latch and flipflop

[kaustubh]

level triggered latch

On one hand it is said a latch is non dependent on clock , or a latch doesnt have clock as input(read SR latch) .. but on the other hand it is said a latch is level trigerred .. hows that possible ?

thanks

 

[vlsi_freak]

level triggered flip flop

Dear Kaustubh

Latch is level triggered and FF is edge triggered. But in many text books they start discussing lathes without clocks and later they come to design with clocks. I guess this what confused you.

Basically in many text books lathes are discussed with simple SR latch. After wards discussion goes to SR latch with clock.

But in reality latches are designs with output changing in levels but FF are designs with output changing in rising or falling edges of the clocks.

Hope it helps

Thanks

 

[salma ali bakr]

why latch is level triggered

The output of a latch takes its value as soon as inputs are present (level triggered)...it doesn't need a clock to synchronize its operation like the case of the FlipFlop...which only changes its output when there's a clock edge (edge triggered)...
so a latch senses the 0 or the 1
but not the transition from 0 to 1 or vice versa...

 

[rania_hassan]

positive level triggered latch

Hi,
as Salma said,
The FF is edge triggered & the latch is level triggered
The FF also consists of two latches one is master working with the high level on the clock & another one is slave working with the low level of the clock
it can be vise versa
best regards,
Rania

 

[kaustubh]

what is level triggered latch

Thanks everyone for the reply.. that clears my doubt
But I have another question..flipflops by default are master-slave ? because we have D flip flops(edge trigerred) without this master and slave arraangement

 

[rania_hassan]

latch is level triggered?

kaustubh,
Could you please, send the DFF schematics you used to explain where are the master & slave on it?
best regards,
Rania

 

[vlsitechnology]

latch is level triggered

Level sensitive means it passes the whole data for that particular clock level like for example if u have a bit as 10101010 so it passes the whole date in either high level or low level of the clock................

 

[kaustubh]

latch level triggered

Here it is :
Also you might want to have a look at this link too http://en.wikipedia.org/wiki/Flip-flop_(electronics)
The link above says that the figure below is an "edge-trigerred Flip Flop" without master-slave arrangement.
Regards
Kaustubh

 

[renee_xu]

latch and flip flop

I think master slave structure will reduce the racing risk. i don't think it is related to edge or level sensitive consideration. latch is faster than ffs by nature and time borrowing can be implemented on latch. There is a lot of definition confusion about latch and ffs. Some textbook refer all the clock storage elements as "register" but some call them flipflop.

 

[xlxlyu]

advantage of level triggered latch

u can treat flipflop as two latch,
the first latch is high level sensitive,the 2nd is low level sensitive,then flipflop is negetive

 

[sekapr]

a latch is level triggered

understanding the difference between latch and flop is critical for timing fix