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18W LED Driver using LNK417

Posted by: golden eye on Tue, 09/22/2015


I had designed one 18W LED driver with output 39.6V@450mA.But whileconnecting load i was getting only 36V@320mA.Can anyone help to get the desired output.I am attaching the schematic of the driver.All deviations in component value is marked in red colour.

Please help to solve this problem.


Thanks and regards



Attachment Size
18W driver schematic 98.34 KB


Submitted by PI-Crumb on Fri, 09/25/2015


Please reduce the value of R10 until you get the desired current. I estimate the value to be around 89k, so you may want to start there.

If you used PIXLS on your design, it actually calculates the required FB resistor. Perhaps the actual bias voltage is lower than the spreadsheet value, which results to lower FB current.