>>The intersect point with the threshold voltage will not change
>>linearly with R, because of the shape of the curve. The RC timeconstant
>>values are only valid for 10%-90% standard step measurements.
>
>??? Never seen that expressed in a formula

I mean of course the change in threshold levels due to varying current in
the IO pins (the saturation curves). The simple RC timeconstant values
given for various CMOS chips are only valid for them (eg. T = 1.19 * R * C
etc) using their specified measurement (usually 10-90% step).

Peter

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