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I was about to choose the MCP2558FD CAN Transceiver for a personal project. I found on the datasheet the following diagram:

enter image description here

If my understanding is good, I can use it as a dual-supply Transceiver.

But I don't understand the physical difference on the CAN bus between single-supply and dual-supply.

What are the benefits and the disadvantages of both configurations ?

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  • \$\begingroup\$ Does this answer your question? CAN Bus transceiver \$V_{RXD}\$/\$V_{IO}\$ pin confusion \$\endgroup\$
    – Justme
    Commented Aug 25, 2023 at 15:36
  • \$\begingroup\$ The picture you posted about internals of the transceiver is pretty useless to look at. Instead look at the typical applications part of the datasheet. After which it becomes very obvious what the purpose of the extra supply pin is. Figure 1-2 and 1-3. \$\endgroup\$
    – Lundin
    Commented Aug 30, 2023 at 6:15

2 Answers 2

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VDD is the 5V supply voltage of the IC.

MCP2558FD specific:
VIO is the power supply of the digital interface, which includes TXD, RXD and S.

If you want to connect the CAN transceiver to a MCU with a lower voltage rating than 5 V (eg 1.8 V, 3.3 V), you'll either need to level-shift the digital interface, or (more conveniently) use a CAN transceiver with an integrated separate power supply for the digital interface.

But I don't understand the physical difference on the CAN bus between single-supply and dual-supply.

There is no difference on the CAN bus interface, since the CAN interface is powered by VDD (5 V) in both cases.

What are the benefits and the disadvantages of both configurations?

If you're interfacing this IC to a 5 V MCU then you don't need the MCP2558FD variant. MCP2557FD is probably cheaper and just as good.

If you have to level-shift the digital interface to 1.8 V .. <5 V, I'd recommend the MCP2558FD variant, because you can then do without a separate level shifter.

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  • \$\begingroup\$ So there is no advantage using a dual supply over a single supply ? \$\endgroup\$
    – Bouboubi
    Commented Aug 25, 2023 at 14:34
  • \$\begingroup\$ If you don't need the level-shifting capability, then there's no advantage using the dual-supply variant. \$\endgroup\$
    – Velvet
    Commented Aug 25, 2023 at 14:39
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    \$\begingroup\$ Thanks for your tips ! I don't like to work on something I don't understand ^^ \$\endgroup\$
    – Bouboubi
    Commented Aug 25, 2023 at 14:45
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This device has a separate supply for the IO and CAN bus sections. It enables interfacing to low voltage (2.5 & 1.8V) MCUs, thus lowering the system power consumption.

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