• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 275 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

SN65HVD230: Help with creating a protection circuit for CAN

Shlok Desai
Prodigy 65 points
Part Number: SN65HVD230
Other Parts Discussed in Thread: TCAN3414

Tool/software:

Hey Friends at TI,

I am trying to create a CAN communication system with the SN65HVD230. To design the system, I have taken reference from some online guides [1], [2] and SN65VHD230 datasheet to design a robust CAN system. Although I have a question with the implementation I did.

Below is the circuit for your reference:


I fear that If there is a constant biased voltage of let's say 42V given on the CAN lines the TVS will go into the avalanche breakdown mode and short the voltage to ground, in which case my device would still be safe but the device providing 42V will be shorted. 

With this fear in mind i plan on putting a fuse on each line, which in that particular case will protect the other device too.

  • Does putting fuse on these lines have any repercussions that I don't know of?
  • How many amps of fuse is required on the line? (I assume a 250mA fuse would be very much more than fine too)
  • From the look at the schematic, do you guys have any other suggestions for the overall implementation?

Thanks,

Shlok Desai

  • 0
    TI__Guru 57207 points

    HI Shlok,

    The schematic looks good overall.

    • Repercussions includes added parasitic which can degrade waveform quality at high data rates, especially if placed too far from the transceiver or using poor quality fuse (choose low resistance, fast-acting fuses rated for electronics while keeping fuse traces short)
    • 250 mA is okay. Ideally you want the fuse to trip lower than the IOS (prior to IOS being met). However, this is also dependent on the max that can be expected in your overall system, ensuring the rating is below the max of the devices connected to the CAN lines.

    You may also see devices rated for higher voltages such as TCAN3414 for example, thanks.

    Best Regards,

    Michael.