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CAN Bus: EMI capacitor values
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PJ Bain:

--- Quote from: free_electron on May 24, 2019, 03:05:58 am ---Much will depend on your cabling.
The cables form a capacitor as well. length dependent , node tap dependent ...
Are you using common mode chokes ?

--- End quote ---

I wasn't going to use CMF, but now it looks like I am :P Issue is the guys writing the requirements have said the default is 250kbps, but they want the bus capable of the full 1Mbps. I am trying to get them to pick one or the other as from what I can tell, the capacitors and CMF will be different for both.

Any suggestions on a CMF? I'm using a really nice ones for the USB2 and USB3 which have built in ESD protection as well and a flow through design which makes layout super nice.
Niklas:
A 51 uH CMC from Murata's DLW43SH-series would be a good start. Then you also have several second source alternatives available from Bourns, Epcos/TDK and others.
You don't need to worry too much about different capacitance values for different baudrates, start with 22pF 50-100V NP0/C0G. Also the tolerance on the CMC is quite wide. The edges on the CAN signals from the transceiver are not affected by the baudrate, only the time between them will change. On older transceivers the enable pin also doubled as slew rate control with an external resistor, but nowadays it is only on/off.
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