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TCAN1462-Q1: Common mode choke coil

Yusuke Mukuno
Expert 7395 points
Part Number: TCAN1462-Q1

Hi expert,

Will TCAN1462-Q1 need the common mode choke coil for TI recommendation usecase?

In TCAN1042 case, datasheet discribed as below,

EMC performance: supports SAE J2962-2 and IEC 62228-3 (up to 500 kbps) without common mode choke

If all TI's CAN tranciver don't need it, could you please let me know technical reason for reducing common mode choke?

Also do you have any limitation in reciever side for using SIC CAN? I think it is improved ringing of signal, so the reciver don't have any concern.

Is it correct?

Thanks

Mukuno

  • 0
    TI__Genius 15345 points

    Mukuno-san,

    Adding a common mode choke is up to the designer of the system. A common mode choke helps reduce common mode noise which matters to a lot of customers when they start looking at the emissions of a device. A CMC will not help with the functionality of a device. In fact, it can even be a hindrance on the system is you use a CMC that is too large. So a system designer has to find a balance between overloading the bus with a CMC and reducing emissions.

    So the TCAN1462 does not "need" a common mode choke but obviously it can help reduce your emissions from the device. For the TCAN1042 we specifically sent that device to the test houses to verify that it did not require a common mode choke to meet the Zwickau standard. We did not do that for the TCAN1462 because most customers require a common mode choke on the bus anyway. I believe that the TCAN1462 driver could support the standard requirement without a common mode choke but since we never tested that I can't make any guarantees. It would be up to the customer to send in their circuit for testing to see if it would meet their emission requirements without a CMC.

    There are no limitations on the receiver side. Since this is a connection directly between the MCU and the transceiver it should be very stable. Obviously with any fast switching signal on the board you have to make sure it does not couple and if the trace becomes very long you can include a series resistor to help with impedance matching.

    Best,

    Chris