CAN transceiver for 12V CAN Bus

Hi Nisal,

I would like to start off by saying that your CAN transceiver is going to interface with your MCU through your TXD and RXD pins. As long as those pins are at the correct logic levels of the MCU then there should be no issue interfacing your CAN transceiver with your MCU.

A lot of our newer CAN transceivers come with a VIO pin that automatically shifts all of the digital input thresholds and output levels to the logic level of your MCU by just supplying it with the same voltage you supply your MCU.

For your specific application this is extremely uncommon. First, what device are you using that has a 12V CAN bus? I'd like to check it out. Once I see what the output of the device is I can better see if it will interface well with our CAN devices

We have a lot of devices that can accept a voltage differential range of +/-12V and operate normally but this is usually due to a ground differential where one ground is at a higher potential than the other. It is not meant for a device that has a recessive level of 6V and it drives a dominant voltage difference of 12V.

Best,

Chris

Hi Chris,

Thank you for the reply. My application is that I have a motor controller that has a 12V CAN bus, and I want to read

data from it. Is there a work around for this?

Nisal

Nisal,

Do you have a part number for the motor controller? Is it a motor controller with a CAN transceiver all in one device? Did you test CAN communication on this device and if you have can you attach scope shots of the dominant and recessive signal? I want to see if the CAN bus really is 12V.

There may be a way to get the motor controller to communicate with one of our 5V can transceivers. What I think will be the issue is getting the 5V CAN transceiver to communicate with a 12V CAN bus. There will most likely be issues with the device not being able to reach the right thresholds.

Best,

Chris

Hi Nisal,

To add a bit to Chris's comments here, a "12V CAN bus" may be referring to the common-mode range of the CAN bus. The CAN standard (ISO 11898-2) defines the electrical characteristics of a CAN differential signal to be between 0V and 5V. The purpose of a CAN transceiver is to convert this differential signal into a single-ended digital signal that can be read/driven by an MCU. The transceiver offers additional protection to the system from electrical energy such as ESD and surge events as well as providing electromagnetic compatibility to the system by reducing susceptibility to and radiation of electromagnetic energy (very helpful for signals running near switching motors). 

For general applications, our 8-pin CAN transceiver TCAN1044 will be suitable for these tasks. Let us know if this looks like it will work for your design or if there are other features you're looking for and we'll help provide a good fit. 

Regards,
Eric Schott