Yeah, what he said. :-) Also, there's a "classic" failure in this topology waiting to bite the inexperienced user. This drive topology _requires_ some amount of time spent with the output driven low to charge the boost capacitor. In practice, this means you cannot achieve 100% duty cycle. 95% probably, 98% maybe, 100% no. -Denny --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .