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I have design LinkSwitch-PH LNK417EG   230VAC   18w   LED driver,

Based on DER-284/278 and AN-49.

But confused about how to select EMI Component, can I use same EMI Component

As per DER-284/278 for 18w?


Thanks in advance,



DER284 /278 are prepared for the 15 W, universal input LED driver applications,  and the same EMI components can be used for  the high line 18 W LED driver application.


My first prototype is complete and starts without any problem.


But output Current is higher than expectation 425ma.  PF .974


Spreadsheet Expected IO (average) 360ma. FB pin R 105k


If I use 100nf cap on v pin it’s become 357ma.  PF .96


If I change FB pin resistor to 119k it’s become 359ma PF .969/97


What shall I do? Which method is correct? Why the current is higher when all values are perfect.


Thanks in advance


It is better to change FB pin resistor to lower the output current.

The output voltage is sensed by the bias voltage, and leakage inductance between the output and bias windings can make the difference between the output voltage and the bias voltage.