At 12:49 PM 5/16/2006, Harold Hallikainen wrote: >We currently have several products running off an unregulated external >12VDC power supply (wall wart). Inside our product, we run through a >1N4001 for reverse polarity protection, then 1n LM7805 to regulate to +5V >(to run the PIC!). Upcoming California Energy Commission regulations >outlaw these external power supplies (due to lack of efficiency and >standby power). We could replace these with 12V regulated switchers, but >that is pretty inefficient. What I'd like to do is replace them with >external 5V switchers, yet continue to allow the use of the old power >supplies. It would be great if there were an LDO equivalent of the TO-200 >LM7805 with reverse polarity protection (so I could get rid of the diode >and its drop). Anyone aware of a drop-in replacement? Note quite drop-in, but I'm fond of both the LM2931 and LM2940. Do note that you MUST include an appropriate output capacitor or it WILL oscillate. How much current do you need and just how much above 5V can you supply? Both of these regulators have the unfortunate property of consuming MUCH current as you approach drop-out - the LM2931 is much worse than the LM2940. If you need only milliamps, the LP2950 would be by far your best choice. Still need that large output cap, though. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 22 years of Engineering Innovation (1984 - 2006) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' 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 PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist