White LED Driver Circuit

[james_sgp]

Hi,
I`m trying to build an LED driver circuit for a torch, I have tried using a Micrel MIC2291 in both Boost & SEPIC configuration but it doesn`t seem to keep the current stable. The power source is a single 18650 LiPo battery, driving a CREE XP-G LED; I`m trying to drive it at between 800~1000mA; would appreciate anyones help in recommending an IC or circuit.

I want to make my own rather than buy as I have a limited space constraint for the PCB (max dia. 19mm , with a dia. 3mm hole in the middle).

James