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Dear TIer:
Base on the schematic of below. If I use VCC1=VCC2=+V Cable driver = 5V, how long can the P82B96 support?
How to calculate the I2C communication cable length?
Table 1 do not show the cable length with condition of Vcc1=Vcc2=+V Cable=5V.
Hello Eric,
Most cable manufacturer's provide specifications for the cable that define the capacitance per unit length. If you don't have that than you may have to measure it.
Here is example of what you will see from a manufacturer. If it isn't in the datasheet you may have to ask the vendor for the information.
-Francis Houde
Eric,
Like Francis said, the limitation is the amount of capacitance on the bus, which is heavily affected by the cable used, but also by the capacitance added by each slave device. This limitation is based on the RC time constant, which affects the rise time of the message waveform (this is why V+ voltage, VCC voltage, pull up resistance, and bus capacitance are important parameters), and thus the signal integrity of the bus waveforms.
This paper explains this concept in more detail, and explains how to calculate the pull up resistances based on different system parameters.
To answer your question, that is going to depend on how many slave devices are present, your cable parameters, and what rate your message is being transmitted.
If you have any other questions, please don't hesitate to post them here.
Regards,
Eric Hackett