Mistake in Reference Design DER-430

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Hi PI,

We kindly request you to clarify the schematic and transformer secondary pin selection of 7.8W flyback LED Driver using LYT2004D (DER-430).

Since the secondary winding (Dot convention) is reversed, starting pin is connected to GND and terminating pin is connected to output diode. 

By selecting the same pin detail we failed to get the regulated output and more over output voltage ramps upto 90VDC in No load condition itself and if we connect LED load the device will blasted out. 

But finally we interchange the transformer secondary pin and we got ultimate regulated CC/CV output. 

We kindly request you to clarify the schematic or do the neccessary change in the design document.


Good luck.


Thanks and Regards,




Thanks for your feedback. I agree that it is misleading. The reversed dot orientation was due to the use of horizontal bobbin and the transformer construction was done  such that the bobbin orientation was inverted. Please refer to the transformer build diagram and winding construction sections for details.

I will let the assigned engineer know about this feedback and ask to update the document.


Hi Crumb,

Thanks for accepting the feedback.