• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 82 subscribers
  • Views 652 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.

C2000 common mode noise rejection for SPI

Melissa Hernandez
Prodigy 10 points

So I need to reduce and get rid of approx 150V of common mode noise on my SPI. I have extremely bad feedback from my AC/DC Inverter and it can really screw up my system. I've been looking at TMS320F2807x, TMS320F2837xD, and TMS320F2837xS but none of these have that isolated SPI I'm looking for, so essentially I need to find an add-on that would work with one of these IC's to achieve my designs needs and reject all common mode noise. What's a good solution that pairs with one of these microprocessors?

  • 0
    Guru 30330 points

    Melissa,

    As you have found, we do not have any on-chip solution to deal with this sort of thing. There are a few things you might be able to try out here. But first I have a few questions.

    1. Please confirm that you are seeing 150 V , and not 150 mV of noise. How are you measuring this? Can you share any scope captures?
    2. Are you using a custom PCB? If you are having this much noise, it is probably reflected on other circuits on the board. Are they affected the same way?
    3. How many layers are on your PCB? you could look into adding an additional few layer to help mitigate the noise using planes and limiting the current loops on the board.
    4. How long are your SPI trace lengths? are they going off board?

    If you are able to design a board, it might be necessary to change the SPI signals into differential pairs using an RS232 driver or an LVDS driver. 

    Again, if you are experiencing this much noise, it sounds like there might be some other underlying issue that you might want to look into.

    Regards,

    Mark