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[SOLVED] D type flip flop as a toggle

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mrinalmani

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Is it reliable to construct a toggle-switch from a D-type flip flop by feeding back Q' to the input? I mean will the hold time, setup time etc etc cause a reliability issue? Is this type of arrangement guaranteed to work as a toggle, regardless of any parameters?
I am not very experienced in sequential designs, please help.
 

regardless of any parameters
What is "any parameter"? Sounds pretty meaningless.

To answer the question for a given logic family, look at hold time and propagation time. You'll notice that it works for any usual logic family. No relation to setup time, by the way.

A parameter that must be observed to make the T-FF work correctly is maximum clock rise- and fall time.
 
Your setup time has to be less than clock cycle minus
CK-Q prop delay. You can pretty much count on that
delay taking care of the hold time and then some.

You could find a way to break it, but probably not before
other things in your design also fail to function. So
relax.
 
Yes, my main doubt was regarding hold and propagation delay. At times the two were critically close, with difference not exceeding 1 or 2 nano-seconds. This tight difference was the main reason for doubts regarding the reliability. By other parameters I meant some other parameter relating to timing requirements that could be a potential cause of trouble.
Thanks for the reply.
 

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