Mark,
You are correct.
I was old when I2C was invented (or designed or realized by Philips.) My EE studies was classical (as in old like classical music) and I am certain that my secondary concentrations in chemistry and physics distracted from the electrical engineering aspects. My elective in thermodynamics likely toasted many brain neurons. I was employed in my concentration for only a year and that was in research which everyone knows is not real-world anything.
The above being a truth, I have forgotten much. But, I do seem to believe that any electronic problem involves reducing it to one or more fundamental "Laws": Ohm's, Joule's, Kirchhoff's, etc.
A ED article (a sales attempt to justify expensive function signal generator) states in summary:
...the actual output waveform’s amplitude changes based on different load impedance under low-frequency conditions. But as frequency increases, the system circuit models become more complex. In this case, it may be necessary to regard the cable as a transmission line and consider reflection and complex load (not only resistance, but also inductance or/and capacitance). Under certain mismatching conditions, the amplitude and shape of a waveform produced by an AFG can end up being significantly different from the ideal source output. These conditions are usually caused by mismatched load impedance or the use of mismatched long cables. The impact of bad reference waveforms can be significant, including measurement errors that lead to inaccurate conclusions and, under extreme conditions, damage to the DUT.
I read that some researchers have resorted to using Joule's Law to explain electron tunneling in semiconductors... as I (think) I remember, Joule's Law is just a restatement of Ohm's Law which is a restatement of Watt's Law ... I can no longer remember the chronology!
People often ask; what is the difference between Watt’s law and Ohm’s law? While Ohm’s law defines the relationship between resistance, voltage, and current in a circuit; Watt’s law defines the relationship between power, voltage and current. However, you can combine these laws to get useful formulas. According to Ohm’s law, I=V/R and V=IR. Substituting these into Watt’s formula, we get:
P=Ix IR=I2R and P=VxV/R=V2/R
I agree that the I2C bus is not a transmission line as Hams radio operators or even AC electrical engineers would recognize; still if I drop back to those old Laws, it makes more sense to me: match everything up, honor the bus specification, minimize power loss and the signal transmission will be better.
Best,
Ray
