LAY OUT FOR UL

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Sir,

     we would like to use the same lay out of der284 for our 15w led driver which we applied for UL recognition. As per my understanding the minimum distance between primary and secondary should be 6.4mm for UL approval. But in the gerber file of der284 it is observed that the mininmum distance between Primary bias negative  point and secondary negative point  is 5.6mm only. For your better understanding I am attaching a picture in which I marked the  area where we get 5.6mm. Is it ok with this 5.6mm? Shall we follow the same gerber for getting UL approval? Please advice.

thanks

SDM

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der284.pdf134.89 KB

Please add a slot between the primary and secondary traces to be sure the creepage requirement is met.

5.6mm will pass both clearance and creepage requirements if the working voltage is <250Vrms but if you don't want to do the measurement, then I suggest to add a slot.

 

Aside from the distance between traces, please note that the transformer core in DER-284 is primary side. You may need to add insulating tape on the core to meet safety isolation requirements between the core and secondary components.