ISO1042: Max load capacitance vs rise/fall times

Hello Ronny, 

Thank you for reaching out. 

Ronny Ståhle said:

So the question is if there is a practical maximum capacitive load for a CAN transceiver ?

You are correct. The timing specs are tested with a bus load of 100pF capacitive load and a 60ohm resistive load to emulate a typical CAN Bus. Rise and fall times will change corresponding to an increase or decrease of capacitive load.

Ronny Ståhle said:

AND/OR if there is a mathematical relationsship between the procentual increase of rise/fall times as a function of the bus load capacitance.

See below links for helpful collateral on designing a CAN bus. Load capacitance will affect the maximum data rate you can use and is highly dependent on the number of nodes and the length of cables. You can find details about calculating a theoretical C_max in section 11 of the 1st link below. 

1. Section 8-11 will also be helpful Top Design Questions about Isolating CAN Nodes Bus Design (Rev. A)
2. Controller Area Network Physical Layer Requirements (ti.com)

I hope this helps.

Best,
Andrew