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ISO7821LLS: ISO7821LLSDWWR

Thomas Egler
Prodigy 20 points
Part Number: ISO7821LLS

Tool/software:

Hello,

In my application for CAN communication, I need a minimum air gap of 15mm. According to the data sheet, the digital isolator ISO7821LLSDWWR has a minimum air gap of 14.95mm in the worst case. Now the question is whether this isolator is still suitable.

  • 0
    Guru 280450 points

    Where did you see this value of 14.95 mm? Section 6.6 and the certifications say "> 14.5 mm".

    Why is your requirement 15 mm? Could it be a value that got rounded? (The air gap is usually specified to achieve a certain voltage rating. What voltage do you need?)

  • 0 in reply to Clemens Ladisch
    Prodigy 20 points

    Thanks for the fast response.

    I calculated 14.95 mm from the tolerances using the housing size and the distance between the housing and the point where the pin touches the PCB (bottom right of page 32 in the data sheet).

    The 15mm air gap comes from the 60601-2-2 standard, which requires 3mm air gap per 1kV.

  • 0 in reply to Thomas Egler
    Guru 280450 points

    The DWW package has been designed to have an external clearance and creepage of at least 14.5 mm, and this is what is guaranteed in section 6.6. So if you apply the 60601-2-2 rules to it, it would not be suitable for more than 4.83 kV.