• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 16 subscribers
  • Views 1085 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

ISOW7841: Isolation distance

Alejandro Martinez de Ilarduya
Prodigy 85 points
Part Number: ISOW7841

Hello,

currently I am working on a design in which ISOW7841 is used to isolate two areas of the PCB. 3.3V are used at both sides.

I have seen on the application notes and some reference designs that configuration 1 (see image below) is preferred.

Is there any real issue using configuration 2 or configuration 3? If so, what is it?

In case there is no real issue using configuration 2, what is the minimum width of the narrow no-copper part? I guess it is related to the maximum voltage isolation that you want. The design will be powered by 5V USB connected to a PC and is part of a medical device.

Thanks in advance,

Alejandro

  • 0
    TI__Expert 6195 points

    Hi Alejandro,

    Great question!

    • Configuration 1 is preferred as you noted. 
    • Configuration 2 is not acceptable.
    • Configuration 3, while not as good as configuration 1, is acceptable.

    The justification for this judgement is creepage and clearance. The distance between the domains you are trying to isolate must keep a certain minimum depending on your isolation requirement. Configuration 1 and 3 keeps this distance. Configuration 2 does not. Furthermore, configuration 3 is slightly less optimal because due to the corners which could create uneven voltage potentials. 

    You can find some more information on PCB design guidelines in the Digital Isolator Design Guide (see page 8). 

    Let me know if that answers your question or if there is any way I can further support you!

    Best regards, 

    Dan

  • 0 in reply to Dan Kisling
    Prodigy 85 points

    Hi Dan,

    thanks for your fast answer. I still have a few additional questions that would imply disclosing some private information. Is there any way I can get in touch with you? (I have not seen any private message option or e-mail)

  • 0 in reply to Alejandro Martinez de Ilarduya
    TI__Expert 6195 points
    Hi Alejandro,

    Absolutely! I would be happy to further assist you. I've sent you a friend request on E2E. If you accept it will open up the private messages option so we can share information that will not be available on the public forum.

    Best regards,
    Dan