Question on digital isolator

[Freshman]

I am using this IC for Isolated CAN interface (https://www.nve.com/Downloads/il5xx.pdf) - IL514E.

My question is, we are giving 3.3V to VDD1 and isolated 5V to VDD2. Whether there's an internal level shifter? Or is VDD2 a supply output?

Also, can this isolator support CAN-FD speeds?

[Andree Henkel]

you need to give 2 supplies, if they are of different level, then the isolator does level shifting too.

I don´t know the requirements of CAN-FD,

but IL514 datasheet says:
2M Bit per Second max data rate - is what it can provide
25ns propagation delay - which may matter in some corner circumstance in case you are doing bidirectional over longer cable and maybe have additional latency
10ns pulse distortion should not matter as 2MB at 50% duty cycle is 250ns pulse length

[Terry Bites]

Either side can be powered from 3.3 or 5V or 3.3 on one side and 5V on the other. What ever suits you.
Its a really crap data sheet in this respect with no real information on powering it.
You need to power both sides of the isolator with supplies that are isolated from each other.
The isolator output levels will depend on the choice of Vdd2.

[Nominal Animal]

I prefer to use TI ISO67xx (1.65V to 5.5V, 50 Mbits/s) or ISO77xx (2.25V to 5.5V, 100 Mbits/s) isolators, especially ISO6721 and ISO7721 having one channel in each direction.  The datasheets (linked, PDFs) are rather clear in my opinion, as a hobbyist myself.

Each side requires their own isolated supply, referenced to the signals on that side, defining the voltage levels on that side.  Each side also has their own ground, to which the supply and signals are referenced to.

You need to add a 0.1µF = 100nF X7R/C0G/NP0 capacitor between each supply and ground, but that's it.  CAN is explicitly mentioned as one use case.  Mouser sells these for under 1€ apiece in lots of 100 or more, so they're not that expensive either.

The two last digits specify the number of channels and the number of channels in the 2-to-1 direction.  Add a Q suffix for automotive versions.