I want an LED Driver RDK to compare electrolytic and non-electrolytic caps. Which one? (15 W, non-dimmable)

RD195 appears to be closest. The board included eveything shown in the associated report ie no need to buy anything.

http://www.powerint.com/sites/default/files/PDFFiles/rdr195.pdf

RD195 is dimmable but you can easily downgrade the design to non dimmable (remove R14, R15, C11, and Q1. Replace R16 with a jumper.

You can also switch the device (U1) to non-dimming mode by replacing R4 with a 24.9k 1% resistor. From your description of evaluation e-cap vs no e-cap that change is not essential as it changes the UV level and the line regulation behavior which should impact that study.

Cheers PI-Chekov

Thanks very much for the suggestion of RDK-195 and how to remove/disable the dimming capability. I will very likely purchase that kit as you suggest.

Before I do, I just want to ask about the design DER-278 using LNK417EG. There are two recent Design Example Reports that seem identical except that one uses non-electrolytic caps (document DER-284 dated July 8, 2011) and the other uses standard electrolytics and has a ripple filter daughter board attached to the output (document DER-288, dated July 18, 2011). These seem like simpler, lower component count, non-dimming designs, and they are identical but for the types of capacitors and the filter at the output. Also, is the difference in efficiency between the two designs in DER-284 (~90%) and DER-288 (~85%) due mostly to the ripple filter on the latter, or is it due to the different types of capacitors?

The two design documents I refer to are here:
http://www.powerint.com/sites/default/files/PDFFiles/der284.pdf
http://www.powerint.com/sites/default/files/PDFFiles/der288.pdf

Is there an RDK available for this design? Or would you say that the RDK-195 would be just as good or better? Again, I will probably buy the RDK-195 as you suggested, I just wanted to investigate all of the options before making a decision.

Cheers, Eli

I'm afraid there's no RD board available for DER284 / DER288 but the result of configuring the RD195 to match those DER design will give similar results.

Cheers PI-Chekov

I'll order a couple of the RDK-195 then. Thanks for your help.

Any thoughts on the differing efficiencies between DER-284 and DER-288 (from my last reply)?

Thanks again, Eli

Sorry missed that part.

The efficiency difference is only due to the ripple filter. This was added to show that you can trade efficiency for output ripple when using ceramic output capacitors.

Ripple is the same ceramic vs e-cap for the same capacitance. However due to volume and cost considerations designs using ceramic caps usually have less capacitance. The lower capacitance results is higher output current ripple.

Cheers PI-Chekov