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TCAN1044V-Q1: Interface forum

Manrae Kim
Prodigy 30 points

Part Number: TCAN1044V-Q1

Hi Guys

I'm making schematic with TCAN1044V-Q1.

Could you recommend what value of bypass capacitor is the best?

I will use decoupling capacitor with 0.1[uF] for VCC and VIO but I'm not sure the values of bypass capactors.

From Manrae.

  • 0
    TI__Guru 74292 points

    Manrae,

    First, I'd recommend going with the TCAN1044AV-Q1 instead of the non-A version. The A-version has an update ESD structure on the CAN bus to help pass Automotive EMC standards. 

    For the bypass capacitors C4 and C5, we typically recommend 10pF - 100pF. The less nodes on the CAN bus, the higher the value. If you're not sure based on the amount of nodes and data rate, then I'd recommend 50pF.

    Regards,

    Eric Hackett 

  • 0 in reply to Eric Hackett
    Prodigy 30 points

    Thank you for the detailed feedback. BTW, C1/C2 and C6/C7 look like decoupling capacitors. According to the datasheet, A decoupling capacitance, typically 100 nF. If so, the sum of C1+c2 should be 100nF, is that right? Have a nice day! Best Regards! Manrae

  • 0 in reply to Manrae Kim
    TI__Guru 53575 points

    Hi Manrae,

    We recommend that one 100nF bypass capacitor is placed near the IC pin. It is also recommended that the board have some bulk capacitance (4.7uF or so) to filter out lower frequencies from the supply rail. This bulk capacitor may be placed further from the IC and shared between multiple devices. This is not accurately represented on the figure because of the focus on other circuits near the IC.

    Let me know if you have any more questions. 

    Regards, 
    Eric Schott 

  • 0 in reply to Eric Schott1
    Prodigy 30 points

    Hi Eric, Thank you so much for the kind feedback. Your comments must be very hulful for using TCAN1044. Have a great day! BR Manrae.

  • 0 in reply to Manrae Kim
    Prodigy 30 points

    Hi Eric, BTW, when looking into the datasheet of TCAN1044AV you recommended instead of TCAN1044V, I found out the Choke is used as shown below.

    Sorry, but could you recommend a Choke so that I can find out it through Digikey???

  • 0 in reply to Manrae Kim
    TI__Guru 74292 points

    Manrae,

    Common-mode chokes are not required for full functionality of a CAN transceiver, they just help with high-frequency noise that may occur on the bus. We typically recommend them for all applications, but they are not required for the CAN transceiver to work correctly.

    TDK common-mode chokes in the ACT series are a good choice, though I know they recently updated that family. Typical choke values are 51uH or 110uH, and I've seen several customers use Cyntec's VFB4532-510, or others from Cyntec. Coilcraft's DLW21SN670HQ2L is another part I've seen customers use, or others from this series at Coilcraft.

    Common-mode choke will depend on the system, but the ones I've recommended are what I commonly see.

    Regards,

    Eric Hackett 

  • 0 in reply to Eric Hackett
    Prodigy 30 points

    Hi Eric, your lecture is helpful for me so that I can complete my schematic thanks to you.  Have a good day! BR Fermi Lim.