THD in LNK41X designs, how to improve with 277VAC input

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LED Driver using LNK417E, works well over the full voltage range of 100 to 300 VAC

PF correction is great, BUT we get around 30% THD error at the high voltage of 277VAC.

Increased the peak detector cap to 1.0mfd, did not help.

KP set to 0.82, will increasing this improve the THD, have to meet 20% max.

You can use PIXLS Designer to determine if your design will meet the required THD or not. Normally, you have to set KP lower for lower THD.


If changing KP still does not improve THD, you can try to put a series R-C circuit from Bulk+ to FB pin. The detailed computation is not yet available but you can start by setting R ~ 4.7Mohms and C ~ 10 nF. Please re-verify all other parameters like efficiency, regulation, etc.


Let me know if you need further help.