Creepage on LNK302 body-material

Posted by: chruge on 07/21/2015

I'm designing an application using your LNK302DN. Our normative inspector says, we Need to provide 2.5mm creepage for between 230VAC circuits an low voltage circuits. This holds for PCB material (FR4).

The issue also exists for the LNK302DN which has about 1.9mm in between ist Drain and the low voltage part. Could you please provide the material class in correspondence to IEC 60355 so I can deliver proofe that LNK302DN is suitable?

PS: I know there is conformal coating and so. My application will be polution degree 2. IEC 60730-1 Table 20.3 states that for 250VAC

- material group III needs 2.5mm,

- group II 1.8mm and

- group I 0.6mm creepage.

If your package falls into II or I, I will not need to bother about coating.

Comments

Hi,

Creepage distance is measured from primary side to secondary side in a offline power supply design. Here the low voltage circuit refers to secondary side cicuit. Since LNK302DN is used on primary side only, so you do not have to meet same creepage distance as siad above.

However I am giving material group classification here.

LNK302DN belongs to Material group-II.

Regards,

PI-NANO

Hi PI-NANO

Thanks for your reply. To ensure that I got you right, I attached an image with the voltage barrier.

Is there an official statement (maybe in the datasheet) that states that LNK302DN is material group II?

Kind regards

Chris

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lnk302.png (110.38 KB)	110.38 KB

Hi,

The picture that you are showing is non isolated power supply. In a non isolated power supply there is no primary or secondary seperation. Its all refered to one side.

Non-isolated designs are used where user does not come incontact with the power supply during operation. Power supply should be completely insulated and user can not touch any metalic parts on the power supply.

If the power supply is not completely insulated then you have to design isolated power supply design. For which you have to design with transformer based power supply topologies.

For your reference you can look at following isolated reference design

http://ac-dc.power.com/design-support/reference-designs/design-examples/der-135-275-w-single-output-isolated-charger/

Regards,

PI-NANO

Hi there

Thanks for your reply. I don't need to isolate my supply. That depends on the application. How ever, I'm still interested in an official statement from PI about the material group.

Is there such a document?

Kind regards

Chris