I2C Layout Methodology

Thread Starter


Joined Apr 5, 2008
I'm using a PCA9532PW IC that uses I2C. I have four of the ic's on a 10" x 1.5" pcb. They are evenly destributed in the vertical direction. I'm not clear what is the correct layout method for the SDA and SCL lines. Can I use a two layer board or is a four layer board best?



Joined Apr 18, 2010
Is there any difference capacitance/frequency wise between a star or ladder layout? I know with 1-wire, for long runs there was a slight change suggested.
10" wouldn't be long though.


Joined Oct 2, 2009
You obviously know what you are talking about.

When you include wire length, frequency and capacitance, you will start to degrade your signal and integrity. If you limit all three then there is little difference between a star or ladder layout.

If you encounter problems with the above and you have to include series resistors and line terminating resistors, then a ladder network would be better.