design a LED driver circuit

[lidas]

I am looking for someone capable of progettarmi a circuit that led to a 28 / 30v feed me from a 12-volt power to the LEDs to function also needs 1.5 / 3 Ah

I have to feed this led
http://www.digikey.it/product-detail/it/bridgelux/BXRC-40A4001-F-03/976-1235-ND/5048136

I wish the circuit has the ability to vary the volts in output and also the amps and that can dim the LED
100%
60%
30%
can you help me

 

[audioguru2]

31W a lot of power in the small area so the LED will get extremely hot. How will you cool it? A number of lower power LEDs will be easier to cool.

An LED sets its own voltage that you cannot adjust. Its current sets its brightness.

 

[davidjackson]

That's not easy. I mean, the schematic is not a big deal, but 90% efficiency at those high voltages are not easy to obtain. Since your output voltage is between the input range, you can't use a pure boost or buck topology. But your best bet is to use a dedicated IC, for example from Linear. 90% is achieved only in the best condition, and mostly for inputs > 10V.