This regulator provides 12 V at 1 A out with an input voltage of 8 to 20 V. Output voltage can be changed by c
harging the ll-kii and 2.49-KOhmhm resistors to provide 2.21 V at the VFB pin of IC1, if desired. If you need to handle a higher input voltage, make sure to clamp the gate of Ql below its 20-V max. rating. Efficiency can exceed 70% for output currents greater than 0.5 A; above 15-V input voltage, more than 2 A of output current can be obtained.