IBIS model dv/dt data , how does it deifine?

here is a part of the IBIS model of "DM9000C" IC

[Ramp]
| variable typ min max
dV/dt_r 1.72/0.86n 1.20/1.13n 1.96/0.66n
dV/dt_f 1.76/0.79n 1.36/1.01n 2.00/0.74n
R_load = 0.50k

does dV/dt 20% mean 80% transition time or 20% to 80% transition voltage ?
I search a lot of Chinese article , but no result, here for help ,thanks

I was going to try and explain! then realised wikki could do it better:
http://en.wikipedia.org/wiki/Rise_time
and these may be useful if you havn't already got them:
**broken link removed**
**broken link removed**

Normally data sheets use 10-90%, but IBIS uses 20-80%, why I cant remember at the moment!!! did a course on it all last year in Germany, but as the SIV tool does all the hard work, you tend to forget the theories!
Oh its transition time

marce said:

I was going to try and explain! then realised wikki could do it better:
http://en.wikipedia.org/wiki/Rise_time
and these may be useful if you havn't already got them:
**broken link removed**
**broken link removed**

Normally data sheets use 10-90%, but IBIS uses 20-80%, why I cant remember at the moment!!! did a course on it all last year in Germany, but as the SIV tool does all the hard work, you tend to forget the theories!
Oh its transition time

Click to expand...

thank you for your reply !
I know the definition of rise time, but I dont know about "IBIS uses 20-80%" , the "20-80%" is the time or the voltage ? you may think about a kind of waveform, if it is not a quite linear , "20-80% time" is not equal to "20-80% voltage"

your handbooks are helpful for my study, and it tells the answer:

the cookbook says:
dv/dt = 20% to 80% voltage swing / Time taken to swing above voltage
so it means the voltage

then here I have and additonal quarstion, many IBIS doc.s data , for example

[Ramp]
| variable typ min max
dV/dt_r 1.72/0.86n 1.20/1.13n 1.96/0.66n
dV/dt_f 1.76/0.79n 1.36/1.01n 2.00/0.74n
R_load = 0.50k

we focus on
dV/dt_r 1.72/0.86n 1.20/1.13n 1.96/0.66n

typ data 1.72V(20%-80%) , 100% voltage is 1.72/0.6 = 2.87V
typ data 1.20V(20%-80%) , 100% voltage is 1.20/0.6 = 2V
typ data 1.96V(20%-80%) , 100% voltage is 1.96/0.6 = 3.3V

100% voltage includes 2V, 2.87V, 3.3V
but the IC is only 3.3V working
only 3.3V data is valid?

if we want to use typ or min data , do we have to set the supply voltage to 2V ?
I dont understand

Glad to help, I need to revise the books myself as I am a bit rusty on IBIS, as I don't delve into it as much as I used to.
I do know that quite often IBIS data has three levels, so you can calculate the worse cases, I will as said have to look up the references regarding this as I cant remember the exact details.

emm...during these days I had read your cookbook all finished, and delved into it. the book you recommanded is great.
I know you tend to forget the theories, so thanks all the same.
the question was not so important already , coz I know it is neglected by the simulation tool , through my research.
If you find looking up IBIS details is a learning , you can review them and I wellcom our sharing