Hi everyone,
I'm having trouble nailing down what the difference is with comparators in regards to propagation delay vs. response time. The definitions that I have found for both say the same thing in many cases, and when they differ, they seem contradictory. - At this point if I am understanding correctly the response time seems to be measured with a sharp stepped input, while the propagation delay looks like it is measured more on a linear input. -- Is this correct?? and if not, can anyone explain the difference between the two??

thank you much for your time,
Mike

 

Do you have a particular comparator in mind? A Datasheet?

The ones I've looked briefly only have a response time.

propagation is usually the delay from input to output of a digital logic gate switch, while response time is how quickly a comparator changes output based on an input change.

 

http://ww1.microchip.com/downloads/en/DeviceDoc/21696f.pdf

Something like this. It is more of a general question I guess. I just am not catching the difference between the two....or if it just a matter of a few manufacturers calling out the same spec a little different.

 

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1004,C1013,P37595,D24967

same thing...

 

When you look at other comparators, the spec with 100mV overdrive is also called response time.

So, I'd have to say "different word for same thing", as the same aspect of the device is being measured.

 

Show us a datasheet, or even separate datasheets, that are contradictory. The one you posted has no mention of a response time spec.

 

LM339 uses "response time" for the same measurement.

 

http://www.national.com/ds/LM/LMV761.pdf

On page 7 they are showing Response vs Input Overdrives Positive Transistion and also propogation delay vs overdrive.....

 

http://www.national.com/ds/LM/LMV761.pdf

On page 7 they are showing Response vs Input Overdrives Positive Transistion and also propogation delay vs overdrive.....

That is a little confusing to the uninitiated (I would have never noticed the use of 2 terms to describe the same phenomenon), but I don't see any contradictory values.