Isolation space of PMP4447

Serdar Köse

The below photo belongs to PMP4447. According to the gerber files, the isolation space is 5.224 mm. Isn't it a requirement to have 8 mm isolation according to IEC60950?

over 10 years ago

0 Chuck Sampson over 10 years ago

Genius 3295 points

Hello Serdar,
Have you checked to see if they are using conformal coating? Sometimes this reduces the creepage clearance requirement. Also they could have a groove in the board to increase the creepage. I checked on www. creepage. com and got a lower number for the creepage requirement. I don't think my result was correct because I guessed at some of the parameters. You might want to check at that website to make sure 8 mm is the requirement.
-Chuck

0 Serdar Köse over 10 years ago in reply to Chuck Sampson

Genius 3360 points

Hi Chuck,

Thanks for the information. I don't have the board, am just following the reference design.I see that the required creepage is about 4mm, I will keep the ~5mm creepage.

0 Serdar Köse over 10 years ago in reply to Chuck Sampson

Genius 3360 points

Do you think it may cause any problem if 0.8 mm standard FR4 board is used instead of 1.6 mm on such PSU?

0 Chuck Sampson over 10 years ago in reply to Serdar Köse

Genius 3295 points

Yes I am sure it does. You need to check vertical as well as horizontal spacing. The arc-over breakdown voltage doesn't change with the direction the potential exists.

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Isolation space of PMP4447