The PMP3976 is another reference design Texas Instruments has available upon request. This design is a SEPIC converter which is somewhat similar to a buck/boost that allows Vin to be above or below Vout. It is a non-isolated, single stage LED driver that has a good power factor, low ripple current, and can drive high or low power lighting loads with constant current. This particular design is good for 100W @ 350mA and is also fairly small.