At 05:26 PM 2/12/03 -0500, Olin Lathrop wrote: > > Question, anyone out there know how possibly to turn off the positive > > rail with an N-channel mosfet instead? This would be much better as > > typically N-channel have a much lower Ron. > >The current flow direction of an N channel FET makes it unusable to switch >a positive power rail on and off. However, you could use an N channel FET >to switch the ground side of the load if this is acceptable to the load. Not if you use the FET in the source follower configuration. As has already been pointed out in earlier messages, you need a gate supply that goes above the positive rail. This can be generated with a variety of methods, or you can use a high-side gate driver that has it built in, or it can be supplied from an existing higher voltage supply if one is already available. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 19 years of Engineering Innovation (1984 - 2003) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics