Efficiency improvement

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Dear Sir

I am using LNK416 based LED driver. The efficiency of the driver is coming around 82%. I want to improve it to 86% to 90%. Whether it is possible to improve the efficiency up to 90%.

1) My operating voltage range is universal 85 - 265 V AC
2) Output Voltage is 40V @ 450mA ( 12 LEDs in Series )
3) The output wattage is coming around 18W.But in design spreed sheet it is recommending us to go for higher LNK switch version. So by using LNK417 and BP pin capacitor 10uF whether the efficiency will improve or not.
4) At present we are using TVS diode P6KE200A for snubber or whether Resister , capacitor RCD combination is required for improving the efficiency.
5) For universal input range margin gap for bobbin of 3.2mm is is needed or not because we are not using T.I.W so we have given a good insulating layer between the layers.

Please give your valuable suggestions to improve our design and efficiency.

Using LNK417 at reduced mode (BP cap=10uF) will give you better efficiency as compared to LNK416 running in full mode (BP cap=100uF) since the former has lower RDS(on), has larger device, and it will run cooler than LNK416 and thus higher efficiency.

RCD snubber won't give you better efficiency vs TVS diode, but higher leakage inductance from the transformer will degrade efficiency.

If you are not using TIW, you need to use margin tape in order to meet creepage and clearance requirements. Just putting insulating layer between layers is not enough to pass Safety regulation.

Please try to minimize leakage inductance on your transformer design, use lower core loss material, use emi inductors with lower wire resistance, use schottky diode.