I got some of these for a customer to try
http://www.tlc-direct.co.uk/Products/LTMR7WW.htmlhttp://www.tlc-direct.co.uk/Products/LTMR7W.htmlcost £15 pounds each
and as they are non-dimmable I though I'd see what they did with different voltages;
They ramp up to full brightness at about 9.5v 330mA then the current goes down;
275mA at 12V
225mA at 14.4V
i.e. exactly like they use a mc34063 type buck converter - these are good for over 35v soI though I'd see if I could use them on 24v:-
138mA at 24v
114mA at 30v
didn't see the point in pushing any further.
just though other here in UK might like to know.
(Not sure how they can claim they're 5watt though)
mab