convert a flipflop to latch

[dalang92]

Anyone can tell me how to convert a flipflop to a latch? thanks!

 

[ebuddy]

You can do it with a FF and a mux.

 

[Milad-D]

I am wondering that ff already consists of 2 latches. In other words, you can say ff is an edge triggered latch.

 

[ebuddy]

In digital design, you may not have the access to the internal nodes of a FF. In some of the standard cell libs, there is no latch available. Occasionally, you'll need To do the conversion.

 

[Prototyp_V1.0]

What kind of flipflop?

If you have a SR flipflop, the common method is to ad a couple of aditional gates* in front that share a common hold input.

* AND-gates or OR-gates depends on the SR flipflop topology.

 

[dalang92]

You can do it with a FF and a mux.

how to do it? can u give me some details?

---------- Post added at 00:26 ---------- Previous post was at 00:24 ----------

What kind of flipflop?

If you have a SR flipflop, the common method is to ad a couple of aditional gates* in front that share a common hold input.

* AND-gates or OR-gates depends on the SR flipflop topology.

thank you for the reply, how about other flip flop? like DFF or JK flipflop?

 

[ebuddy]

how to do it? can u give me some details?

How do I do it? Give it a try on this.

ff i_ff (.clk(!CLK), .d(D), .q(Q));
mux i_mux (.inp0(Q), .inp1(D), .out(OUT), .s(CLK));

 

[dalang92]

how to do it? can u give me some details?

How do I do it? Give it a try on this.

ff i_ff (.clk(!CLK), .d(D), .q(Q));
mux i_mux (.inp0(Q), .inp1(D), .out(OUT), .s(CLK));

ok, thank u!

 

[qieda]

Hi,

can we use only the mux

mux i_mux (.inp0(OUT), .inp1(D), .out(OUT), .s(CLK));

??

regards

 

[Jack// ani]

Hi,

can we use only the mux

mux i_mux (.inp0(OUT), .inp1(D), .out(OUT), .s(CLK));

??

regards

Yes, as a matter of fact you can.

Check this out: https://www.asic-world.com/images/digital/mux_latch.gif

 

[dalang92]

Yes, as a matter of fact you can.

Check this out: https://www.asic-world.com/images/digital/mux_latch.gif

But I think it's mux to latch, not flipflop to latch...

 

[Jack// ani]

But I think it's mux to latch, not flipflop to latch...

That's right, his question was different from your.

 

[qieda]

How do I do it? Give it a try on this.

ff i_ff (.clk(!CLK), .d(D), .q(Q));
mux i_mux (.inp0(Q), .inp1(D), .out(OUT), .s(CLK));

to be honest
In the circuit from ebuddy the latch functionallity is comming from the mux.
The FF is more or less just in to fullfill your question,
but it isn't needed at all and you could also remove it

So for me this solution did not convert a FF into a Latch, you just add a latch to the FF.
;-)

regards

 

[ebuddy]

to be honest
In the circuit from ebuddy the latch functionallity is comming from the mux.
The FF is more or less just in to fullfill your question,
but it isn't needed at all and you could also remove it

So for me this solution did not convert a FF into a Latch, you just add a latch to the FF.
;-)

regards

Well, in the solution I proposed, the memory element is the FF, not the mux.

This kind of question is more an interview question than a practical question. The OP is asking for a latch from FF. So if the solution does not have FF, then the answer is most likely not the one expected by the interviewer.