I wonder if it would be a good design to have a buck pre-regulator SMPS that was heavily filtered followed by a linear regulator dropping a few volts. The buck supply would have a slow feedback response because of the filtering but the floating linear reg could make up for it. - Martin -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist