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J1939 CAN EMC/EMI

OXO
Prodigy 40 points

Other Parts Discussed in Thread: SN55HVD251, SN65HVD1050, SN65HVDA1050A-Q1

I have an automotive sensor we designed with SN55HVD251, and I need to improve the EMC/EMI so I can be certain to pass EMC testing.

How much better is the SN65HVD1050 than the part I already use, and is it appropriate to add ferrites to get the emissions lower?

Any and all advice welcome :)

Chris

  • 0
    TI__Mastermind 20820 points

    Hi Chris,

    The SN55HVD251 is an industrial CAN transceiver and was not designed with automotive EMC/EMI requirements in mind. The SN65HVDA1050A-Q1 is probably more of the type of product you are looking for since this is an automotive application. The Q1 versions of our CAN transceivers have gone through an automotive qualification process and either meet or exceed EMC/EMI requirements. In some application a few external components may have to be implemented to help reduce the EMC/EMI but this is dependent upon data rate, layout, device implemented and test level requirements.

    There are several things you can do to reduce EMI aiding in system level electromagnetic compatibility (EMC). A common technique employed is split termination with a common mode filter cap instead of the standard 120 ohm termination. To reduce EMI even more you could place a common mode choke between the CAN bus pins and the termination thereby filtering more of the common mode noise before it enters the bus or enters the device from the bus. Take a look at this article written by a colleague of mine describing the benifits and implementation of split termination: https://e2e.ti.com/support/interface/industrial_interface/w/industrial_interface/2513.can-termination-techniques. Also, here is a good app note that was written some time ago regarding the use of common mode chokes in automotive applications: http://www.ti.com/lit/an/slla271/slla271.pdf

    This link will bring you to all of our automotive qualified CAN transceivers: http://www.ti.com/lsds/ti/interface/can-products.page#p305=&p1498=Automotive

    Please take some time to filter through the devices and select the one that best fits your applications needs. Let me know what other questions you have and I will be glad to help.