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LT3960 I2C to CAN common mode rejection on CAN with capacitor

Category: Hardware
Product Number: LT3960

Hello,

I request more explanation on the common noise filtering capacitor on page 17 of the LT3960 datasheet https://www.analog.com/media/en/technical-documentation/data-sheets/lt3960.pdf.

How is the common mode noise is suppressed with the capacitor?  The olive line at the bottom of the graph is labelled CANSDA_CM. What does CANSDA_CM represent? Is it  0.5*CANSDAH + 0.5* CANSDAL? What is the difference between the blue and green lines of figure 11 and 12 which make such a huge impact on the CANSDA_CM?

I was expecting common mode filtering would be done something along the lines of this at page 5-13:

https://www.analog.com/media/en/training-seminars/design-handbooks/designers-guide-instrument-amps-complete.pdf

Please help.

Thanks.