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27W LED-Powersupply with LYT4226E

Posted by: MerzGmbh on 04/18/2015

Dear Sir,

we dev a LED-Driver based on the LNK420 (RDR-290). After many maesrued systems and varation we get a transformer desing that work. But now we have a problem with the effecient. We get a eff. of 85% @ 230V AC and a Inputpower of 30W. I optimized the output Diodes and the Drain Diode (VF). 

What is the best thing to optimize the eff.? Increase the device size from 35W max. to 50W? Or the Transformer Sec. winding (smaller AWG)?


Thanks for our help!


Attachment Size
First part transformer 1.54 MB
Second part transformer 784.08 KB


Submitted by PI-Dunwell on 04/20/2015

You're already using the largest device size so I guess optimizing your transformer is the best way to go.

Submitted by MerzGmbh on 04/21/2015

Many thanks for the quick response. Can you make me please say how we can optimize the Transformer best? What are the parameters for the efficien?
Many thanks to the brilliant support

Submitted by PI-Dunwell on 04/24/2015

Optimizing efficiency on transformer is the same as in any power supply.

To try to reduce copper losses by increasing CMA capacity of the windings. You may also try reducing the number of layers to reduce proximity losses. What you need is to find the right balance on copper size and number of layers that gives you a minimum number for copper losses and ofcourse this depends on the geometry of the transformer you're using. 

You can use a low loss core material say PC95 to reduce core loss.

I also attached the design guide for LinkSwitch-Ph in case you dont have it yet.

Hope this helps.



Attachment Size
an49.pdf 2.21 MB