LM338K or Mean Well LDD-H for flicker free 3W LED driver?

[smilem]

Hello, I know for a fact that LM338 as constant current source is flicker free as LED driver, but it heats up and is not power efficient. Size is another problem.

The Mean Well LDD-H is a box about 2 x 3 cm in size
http://www.meanwell.com/search/LDD-H/LDD-H-spec.pdf

The dimming is done by separate power source of >2.5 ~ 6VDC if I read data sheet correctly. But does it flicker?
So far the controllers I got from ebay do flicker (no you can't see it by eye) but a camera can see it.
As my project needs flicker free camera light source I would like to ask for help.

 

[(*steve*)]

Any switching regulator will cause flicker. If the switching frequency is high enough, that flicker should not be noticable.

The problem may not be the switching frequency itself (40kHz would be invisible to anything other than a high speed camera) but due to low frequency variation if the regulator operates start-stop rather than continuously.

A regulator designed to operate from a wide range of input voltages, it may well not operate constantly for voltages above the lower input limit. The ones you show have a large input voltage range. Presumably the input voltage must exceed the output voltage. You are best off keeping this voltage differential small as this will tend to make the regulator operate continuously.