Math help Rise time / Capacitance of buss tR/Cbus
metron9
Posts: 1,100
When it comes to datasheets, I am trying to understand every detail as best as I can but sometimes an example of real data would help my understanding. Even though I can make it work without knowing it.
I am working with the Ramtron FM24C64. There is a formula to find the maximum restor to use for a two wire buss on page 3. (link to datasheet link.. and attached schematic showing formula)
www.datasheetcatalog.com/datasheets_pdf/F/M/2/4/FM24C64.shtml
Reading the Table of data
The Table shows three sets of data MIN and MAX values
Are these three sets 4.5V 5V and 5.5V conditions?
tR= Input Rise Time
Cbuss = Capacitance of the buss
Questons
1. Is this correct interpretation?
2. How would one measure Cbus
Last question is Capacitance value for the formula, is it in Pf?
So Rmax=tR/Cbuss
at 5V tR=300 ns
If my buss capacitance was 100pF
300/100 = 3
So as you can see, I am lost on this minor detail.
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Think outside the BOX!
I am working with the Ramtron FM24C64. There is a formula to find the maximum restor to use for a two wire buss on page 3. (link to datasheet link.. and attached schematic showing formula)
www.datasheetcatalog.com/datasheets_pdf/F/M/2/4/FM24C64.shtml
Reading the Table of data
The Table shows three sets of data MIN and MAX values
Are these three sets 4.5V 5V and 5.5V conditions?
tR= Input Rise Time
Cbuss = Capacitance of the buss
Questons
1. Is this correct interpretation?
2. How would one measure Cbus
Last question is Capacitance value for the formula, is it in Pf?
So Rmax=tR/Cbuss
at 5V tR=300 ns
If my buss capacitance was 100pF
300/100 = 3
So as you can see, I am lost on this minor detail.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Think outside the BOX!
500 x 375 - 19K
977 x 767 - 147K
Comments
(I'm just commenting on the math, not on whether the underlying assumptions are correct)